Functional tremor.

Functional tremor is the most common functional movement disorder. It can be diagnosed with clinically definite certainty at the bedside by ascertaining its inconsistent (distractibility, frequency variability) and incongruent features (entrainment, ballistic suppression), requiring no additional neurological investigations except, in selected cases, those serving to elevate the diagnostic category to laboratory supported using accelerometry and surface electromyography. In the background of excessive attention to the affected body part and abnormal beliefs and expectations, functional correlates include the impairment of emotion processing, sense of agency, and abnormal connectivity between limbic and motor regions. While the treatment options remain under-studied, promising interventions in physiotherapy, cognitive behavioral therapy, and other psychotherapies are under evaluation to assessing their efficacy in attenuating this important source of neurological disability. This article is part of the Special Issue "Tremor" edited by Daniel D. Truong, Mark Hallett, and Aasef Shaikh.