Esophageal motility disorder - has Chicago classification v4.0 simplified our management?

Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16]. The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4. 0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17]. The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16]. The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4. 0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17]. The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16]. The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4. 0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17].The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.Review purposeAddressing dysphagia is vital due to its prevalence and impact on healthcare expenditure. While high resolution manometry (HRM) effectively evaluates esophageal dysphagia, its role in oropharyngeal dysphagia and upper esophageal sphincter (UES) dysfunction remains debated. The fourth iteration of the Chicago classification (CC) offers an algorithmic approach for diagnosing abnormal motor patterns via HRM. This review assesses the CC's impact on dysphagia management.The Chicago classification version 4.0 emphasizes auxiliary and provocative techniques when the algorithm falls short of a conclusive diagnosis. It introduces stricter criteria for previously ambiguous conditions like ineffective motility and esophagogastric junction outflow obstruction. This version also introduces the concept of conclusive and inconclusive classifications based on symptoms, provocation maneuvers, and supportive testing minimizing ambiguity.The Chicago classification v4.0 remains a useful tool for the diagnosis of well characterized esophageal motility disorders. However, major limitations include reliance on HRM and a focus on distal esophagus contractile characteristics without considering proximal esophagus or upper esophageal sphincter, both of which can sometimes be the only evident abnormality in patients with dysphagia. Despite efforts to reduce ambiguity, diagnostic challenges persist. These limitations can be addressed in future updatesPapers of particular interest, published within the annual period of review, have been highlighted as:Esophageal motility disorders affect bolus transit in the esophagus. The Chicago classification (CC) is a foundational diagnostic system that has evolved through three updates [1-3,4]. It employs an algorithmic approach based on high-resolution manometry (HRM) metrics. This review examines version 4.0's key changes, analyzes its diagnostic efficacy, limitations, and potential future directions. no caption availableOur understanding and classification of esophageal motility disorders have progressed alongside technological and pathophysiological advancements. A classification scheme predating the Chicago classification was first proposed at the end of the 20th century with the aim of standardizing manometric criteria for the abnormal esophageal motility patterns observed during low resolution manometry [5,6]. The Chicago classification emerged in the 21st century to systematize abnormal patterns identified using HRM and pressure topography visualization. Initial development occurred at Northwestern University, USA, with a 2008 publication marking a pivotal moment. The CC characterizes motor anomalies based on observed patterns while integrating supportive tests and provocation maneuvers for precision.Since inception in 2008, the Chicago classification has refined and expanded diagnostic criteria through versions 2.0 (2012), 3.0 (2015), and 4.0 (2021). Updates incorporate research insights, enhancing diagnostic accuracy and inclusiveness. The CC has fostered global collaboration and a common framework facilitating information exchange among clinicians and researchers. As the system evolves, research and technological advances continue to refine our understanding of esophageal motility disorders with the CC guiding reliable diagnoses and personalized treatment strategies.This section highlights significant updates in the latest Chicago Classification version. These changes, devised by a 2-year collaboration among 52 international experts, emphasize their rationale and potential impact on esophageal motility disorder diagnosis. Notable modifications from v3.0 include:Maintaining a focus on standardization and ambiguity reduction, CC v4.0 preserves the classification approach distinguishing EGJ outflow disorders and peristalsis disorders (Fig. 1). The working group addressed seven priority areas aiming to establish consistency in evaluation and diagnosis.Chicago classification version 4.0 diagnostic algorithm.The Chicago classification has indeed enhanced comprehension and simplification of diagnosing esophageal motility disorders. Version 4.0, like its predecessors, refined the diagnostic algorithm based on recent research findings. However, no classification system is devoid of limitations. We address version 4.0's drawbacks, as addressing these is vital for further enhancement in future updates.The classification's complexity with numerous subtypes and criteria poses a challenge for clinicians and gastroenterologists to fully grasp. This complexity could lead to misinterpretation, misdiagnosis, and impact patient care decisions. Furthermore, ambiguity remains for disorders such as IEM when the diagnosis changes between upright vs. supine primary positions [11].While HRM is valuable, it might not fully capture all aspects of esophageal motility. Recent research suggests that esophageal wall compliance, not measurable by HRM, may be the key abnormality in some patients with dysphagia [12] and normal HRM findings [13]. Some disorders with atypical or intermittent patterns may be missed, potentially resulting in underdiagnosis or misclassification. Notably, HRM lacks insight into the effects of swallowing reflexes, sensory abnormalities or interaction between esophageal motility and reflux, potentially leaving gaps in diagnosis. Similarly, hypervigilance and hypersensitivity have been described in dysphagia patients, factors that are not considered in the diagnostic scheme [14,15]. This limitation restricts a comprehensive understanding of the underlying pathophysiology of dysphagia. Furthermore, HRM is invasive and has been associated with posttraumatic stress [16].The Chicago classification overlooks proximal esophagus and well documented UES disorders. Disorders such as cricopharyngeal dysfunction and retrograde cricopharyngeal dysfunction can contribute to symptoms unaccounted for by the CC (Fig. 2a, b). There is some data to suggest that there may be dysfunction of the proximal striated muscle esophagus in some of these patients (Fig. 3a, b). For instance, a large peristaltic break is often due to a weak/hypocontractile proximal esophagus even when the distal esophagus contractile vigor is preserved. This often involves the transition zone between the proximal and distal esophagus, resulting in bolus escape in this region.Example of a HRM tracing in a patient with retrograde cricopharyngeus dysfunction (R-CPD). There is a failure of the UES to relax resulting in air-trapping within the esophagus as shown by increase in impedance. This patient reported chest pressure/pain and inability to belch. HRM, high resolution manometry.Example of a HRM tracing showing normal distal esophagus contraction but weak proximal esophagus contraction (a). Figure (b) shows impedance tracing (magenta color) depicting bolus escape from the region of the weak proximal esophagus. Per current CC, this was reported as "no Chicago classification abnormality" in this patient with dysphagia. HRM, high resolution manometry.The role of concurrent impedance monitoring is still incompletely addressed. Bolus clearance issues often accompany abnormal esophageal motility but are not fully integrated into the classification. Addition of bolus clearance to CC v4.0 criteria for IEM improved its prediction of outcome following magnetic sphincter augmentation [17]. The CC may not offer clear treatment directions, particularly for nonachalasia disorders like EGJOO, IEM, and opioid-induced esophageal dysmotility. Overlapping features of certain motility disorders create uncertainty in therapeutic decisions.The CC's foundation in Western populations raises concerns about applicability to diverse ethnic groups and regions. Variances in motility patterns across different demographics might not be adequately represented. For instance, recent studies from Asia and North Africa suggest different prevalence of achalasia subtypes compared to the United States [18,19]Additional issues for Chicago classification:So, while the Chicago classification has undoubtedly been transformative, its complexity, reliance on HRM, and omission of certain aspects of esophageal motility present challenges. Addressing these limitations will be pivotal for enhancing the classification's utility in guiding accurate diagnoses and optimal patient management.