EEG criteria for diagnosing nonconvulsive status epilepticus in comatose - An unsolved puzzle: A narrative review

Introduction: Nonconvulsive status epilepticus (NCSE) is an important and often unrecognized cause of impaired awareness especially in critically ill patients, which can easily be missed. Electroencephalography (EEG) findings in clinically suspected cases are the mainstay of diagnosis. Review summary: The EEG diagnostic criteria for NCSE have evolved over the past three decades. Furthermore, recent advancements in EEG technologies such as continuous EEG monitoring, and emergency department EEG, along with development of different diagnostic criteria, have increased the detection rate for NCSE in suspected cases. However, treating physicians should have a higher index of clinical suspicion and a lower threshold for recommending this valuable investigation. The introduction of different diagnostic criteria has made it easier for electroencepha-lographers to report NCSE; nevertheless, diagnosis is not always straightforward. This narrative review aimed to define and discuss the available literature on different EEG diagnostic criteria for NCSE. Conclusion: There is a need for further prospective research to strengthen the diagnostic accuracy of the available diagnostic criteria, the modified Salzburg Consensus Criteria for NCSE (mSCNC) and updated American Clinical Neurophysiology Society (ACNS) 21 criteria, to verify their accuracy to detect NCSE in comatose patients.