Essential tremor: an overview.

Essential tremor (ET) is typically 4 to 12 Hz frequency, absent at rest, maximal during maintenance of a posture, attenuated during movement and often accentuated at the termination of movement. Prevalence in Americans is 300 to 415 per 100,000 population, and it is frequently disabling. There is controversy about the central or peripheral origin of ET. There is no specific diagnostic test for ET; the diagnosis is made clinically. Ethanol is the most effective suppressor of ET. Treatment is with beta-adrenergic blockers, primidone, and benzodiazepines. The first systematic description of essential tremor (ET) was 100 years ago by Dana in 1887, who regarded the disorder as a hereditary tremor that was a form of "motor neurosis." Most subsequent contributions to the English literature consisted predominantly of case reports until Critchley's exhaustive survey of the subject in 1949. The disorder has been variously termed essential, benign essential, hereditary, familial, idiopathic, juvenile, presenile or senile tremor.