Upper-extremity disability in essential tremor.
OBJECTIVE: To determine the extent of disability in subjects with essential tremor (ET) using time-based, standardized measures of upper-extremity function. DESIGN: Descriptive case series. SETTING: Motor performance research laboratory. PARTICIPANTS: Thirty subjects with ET (mean age, 58.3+/-13.7 y) and 28 healthy controls (mean age, 58.4+/-12.4 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We assessed upper-extremity function using the Box and Block Test, Purdue Pegboard Test (PPT), and Test Evaluant la performance des Membres supérieurs des Personnes Agées (TEMPA). We measured tremor severity with laser displacement sensors. RESULTS: Subjects with ET-type tremor in 1 or both hands performed significantly worse than controls on all unilateral and bilateral tasks (P range, .038-.001) except on the PPT for the dominant side. ET subjects without ET-type tremor in the dominant hand also performed significantly worse than controls on the TEMPA unilateral tasks (P=.043). Performance on the 3 functional measures correlated moderately with tremor severity for the nondominant hand. CONCLUSIONS: Subjects with ET show measurable disability on time-based measures of upper-extremity function. However, our findings are consistent with other reports that tremor severity does not correlate well with disability, especially with regard to the dominant upper extremity.