Functional tremor is the most common presentation of functional movement disorders and can occur in isolation or together with other functional symptoms, including other abnormal movements. The diagnosis of functional tremor is based on positive features on history, examination, and, if necessary, neurophysiological studies. Historical features include: sudden onset, a preceding physical event or injury, variability in severity with or without remission, variability in affected body parts, the presence of other somatic symptoms, and a history of failed therapeutic trials. Positive signs on examination include: variability in the frequency, direction, and distribution of the tremor; clear coherence in the different body parts affected; reduction or elimination of the tremor with distraction; and tremor amplification with attention, entrainability, suggestibility, and the presence of co-contraction. Neurophysiological studies include electromyography and accelerometry and can be helpful to make a laboratory-supported diagnosis when the clinical picture is less clear.
Keywords: functional movement disorder; functional neurological disorder; functional tremor.
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