Functional Neurological Disorders: A Comprehensive Review

Functional neurological disorders (FNDs) are altered voluntary symptoms incompatible with recognized medical or neurological conditions, causing significant distress to the patient. It is not a diagnosis of exclusion, but positive signs must be used to make a confident diagnosis and initiate appropriate management at the earliest. The understanding of FNDs has evolved over decades from supernatural power in the Mesopotamian age to the current neurocircuitry dysfunction and yet continues to be an area of active research. The evolution of various theories and terminologies for these disorders has been highlighted in this article in addition to key clinical signs for the diagnosis of various subsets of these disorders. In this article, FNDs are grouped into functional limb weakness, functional seizures, functional movement disorders, functional gait disorders, functional pseudosyncope, and functional cognitive dysfunction, and important clinical clues of diagnosis are discussed. FNDs contribute to about 5-10% of outpatient neurological consultations, and identification of appropriate positive clinical signs plays a key role in early diagnosis and judicious use of investigations (Bennett et al., 2021).¹ Management of these disorders involves a multidisciplinary approach ranging from effective communication of the diagnosis and management of psychiatric comorbidities to individually tailored counseling and therapy sessions.