Functional Neurological Disorder: Diagnostic Pitfalls and Differential Diagnostic Considerations

Diagnosis of FND relies on the clinical examination, during which rule-in signs consis-tent with the diagnosis should be assessed for. Clinicians should consider their degree of certainty in the diagnosis based on the clinical picture, and consideration could be given to use of "probable" or "possible" FND categories if diagnosis is unclear due to the absence of robust rule-in signs or when only one sign is present, for example. Although not discussed at length in this article, the possibility of concurrent neurologic or psychiatric disorders should be considered as a routine part of the assessment. There are several commonly encountered diagnostic pitfalls regarding an FND diagnosis, which vary based on FND phenotype. Neurologists and neurologic trainees should be aware of these pitfalls, in order to bring a high level of clinical acumen and diagnostic certainty to the assessment of this population.