An update on essential tremor.

Essential tremor is a well-defined syndrome of postural and kinetic tremor in a characteristic distribution. In some patients, impaired tandem walking, intention tremor, and rest tremor are also seen. An increasing body of clinical, neuropathological, and epidemiologic evidence suggests that essential tremor is a heterogeneous disorder. The evidence is discussed in this update. Recent advances in the treatment of this condition are also reviewed.