LAUSR

Functional or psychogenic movement disorders (FMD) represent a common diagnostic problem in routine neurologic practice. Estimates vary, but most published data suggest that 10%–15% of patients presenting with involuntary movements, such as tremor, myoclonus, or tic, have no evidence for an organic brain disorder.1 However, the exact incidence of FMD remains unknown, given the many challenges in diagnosis including the lack of a gold standard confirmatory test. Moreover, the division between organic and nonorganic etiology has been challenged and functional imaging studies in patients with obvious FMD have suggested abnormal metabolic activity in the sensorimotor cortices, cerebellum, and limbic regions, implying an organic origin of these clinical abnormalities.2,3 Likewise, advanced neuroimaging studies revealed analogous abnormalities of the sensory-motor network and its connections in patients with psychogenic nonepileptic seizures, providing a unifying pathomechanism that may underlie both these conditions.4