Essential tremor: emerging views of a common disorder.

Essential tremor (ET) is the most prevalent tremor disorder. ET has traditionally been viewed as a monosymptomatic disorder characterized by a kinetic arm tremor, but this definition is gradually being replaced. The clinical spectrum has come to include several motor features, including tremor and ataxia, and several non-motor features, including possible cognitive impairment and personality disturbances. Postmortem studies are revealing several different patterns of pathology. The emerging view is that ET might be a family of diseases, unified by the presence of kinetic tremor, but further characterized by etiological, clinical and pathological heterogeneity. Effective pharmacological treatments for the disorder remain limited, although new insights into disease mechanisms might result in more-effective therapies. In addition, recent investigations of environmental toxicants that might be linked to ET open the way towards primary disease prevention through a reduction in exposure to these factors.