A comparison of different bedside tests for essential tremor

OBJECTIVE: To compare the performance of different bedside tests for essential tremor (ET). BACKGROUND: Numerous tests (for example, writing, arm extension) may be used to elicit tremor in patients with ET. In large epidemiological surveys in which many patients must be evaluated efficiently, knowledge about the relative performance of these tests would be useful. METHODS: 154 subjects (42 with ET and 112 control subjects) were part of a community-based family study of ET in northern Manhattan, New York. Subjects underwent a tremor interview and a videotaped tremor examination which included six different tests for ET. Each of the six tests was performed with both the dominant and the nondominant arms. Two neurologists reviewed the videotaped examination and rated the severity of tremor during each test. Tremor ratings were 0 (none), +1 (mild), +2 (moderate), and +3 (severe). RESULTS: Among ET cases, there was considerable variation in the performance of each bedside test. With some tests (nondominant arm extension), as few as 48.8% of the ratings were > +2 and 29.8% of the ratings were 0 (no tremor). With other tests (finger-to-nose maneuver using nondominant arm), as many as 88.1% of the ratings were > +2 and only 2.4% were 0. Among the control subjects, there was also considerable variation in the performance of each test. Using some tests (finger-to-nose maneuver using nondominant arm), as many as 26.3% of the ratings were > +2, 72.8% were > +1 tremor, and only 27.2% of the ratings were 0. CONCLUSIONS: The performance of the tests varied considerably. In settings in which only one or two tests must be selected to screen a population, tests that are most likely to be abnormal in an ET case (finger-to-nose maneuver) could be used. In settings in which it is also desirable to exclude normal subjects, tests such as sustained arm extension, pouring water, or drawing a spiral could be used. Data regarding the performance of bedside tests for diagnosing ET are central to the design of research strategies for the clinical evaluation of patients with ET.