essential tremor, an involuntary fine shaking of the hand, the head, and the face, especially during routine body movements. It is a familial disorder inherited as an autosomal-dominant trait and appears during adolescence or in middle age, slowly progressing as a more pronounced disorder. The precise cause of this condition is not known. Essential tremor is aggravated by activity and emotion and can be reduced in some patients by the administration of mild sedatives, such as propranolol and diazepam, or with alcohol consumption. Also called benign essential tremor, familial tremor. Compare parkinsonism.
