Tremor.

Tremor may be defined as an involuntary movement that is rhythmic (ie, regularly recurrent) and oscillatory (ie, rotating around a central plane) and may manifest in a variety of ways; accordingly, tremor has a rich clinical phenomenology. Consequently, the diagnosis of tremor disorders can be challenging, and misdiagnoses are common. The goal of this article is to provide the reader with straightforward approaches to the diagnosis and treatment of tremors. Focused ultrasound thalamotomy of the ventral intermediate nucleus of the thalamus is an emerging and promising therapy for the treatment of essential tremor. The evaluation should start with a detailed tremor history followed by a focused neurologic examination, which should attend to the many subtleties of tremor phenomenology. Among other things, the history and examination are used to establish whether the primary tremor is an action tremor (ie, postural, kinetic, or intention tremor) or a resting tremor. The clinician should then formulate two sets of diagnoses: disorders in which action tremor is the predominant tremor versus those in which resting tremor is the predominant tremor. Among the most common of the former type are essential tremor, enhanced physiologic tremor, drug-induced tremor, dystonic tremor, primary writing tremor, orthostatic tremor, and cerebellar tremor. Parkinson disease is the most common disorder of resting tremor. This article details the clinical features of each of these disorders, as well as those of additional tremor disorders.