Essential tremor: Clinical features and diagnosis
- Daniel Tarsy, MD
Daniel Tarsy, MD
- Professor of Neurology
- Harvard Medical School
- Ludy Shih, MD
Ludy Shih, MD
- Assistant Professor of Neurology
- Harvard Medical School
Tremor is defined as a rhythmic and oscillatory movement of a body part with a relatively constant frequency and variable amplitude. It is caused by alternating contractions of antagonistic muscles. Tremor is the most common of all movement disorders, and essential tremor (ET) is the most common neurologic cause of postural or action tremor.
This topic will cover the classification, clinical features, diagnostic evaluation, and treatment of ET. The treatment and prognosis of ET are discussed separately. (See "Essential tremor: Treatment and prognosis" and "Surgical treatment of essential tremor".)
Other types of tremor are reviewed elsewhere. (See "Overview of tremor".)
CLASSIFICATION AND TERMINOLOGY
ET is a type of postural and action tremor; these are elicited during examination under two circumstances: with the arms suspended against gravity in a fixed posture; and during the course of goal-directed activity. (See "Overview of tremor", section on 'Postural and action tremors'.)
ET is referred to as familial tremor when there is a family history (see 'Genetics' below). The term "benign essential tremor" was used in the past to distinguish ET from Parkinson disease. However, the use of "benign" as a modifier for ET is best omitted, since the tremor can be severe and disabling. (See "Essential tremor: Treatment and prognosis", section on 'Prognosis'.)
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