Electromyographic differentiation of tremors

Objective: The aim of this study was to explore the opportunity for differe ntiation of tremors on the basis of the electromyographic examination. Methods: We report data from 525 patients with different types of tremor in cluded in this study. Two hundred and twenty patients with essential tremor , 110 patients with Parkinson's disease, 24 patients with midbrain tremor, 22 patients with cerebellar tremor, 120 patients with enhanced physiologica l tremor due to anxiety, and 29 patients with psychogenic tremor participat ed in the study. A detailed neurological and electromyographic examination was performed. The tremor was studied in all limbs positions. Surface elect romyographic recordings of the most involved body part were performed to al l patients. Results: According to the electromyographic examination all patients were d ivided to two groups: Patients with synchronous tremor and patients with al ternating tremor in the antagonist muscles. The comparisons were performed only between the patients with tremor caused by different etiology within t he group of synchronous or alternating tremor. The group of tremors with sy nchronous pattern included the patients. with essential tremor type A (with synchronous activity), cerebellar, and enhanced physiological tremor. The group of tremors with alternating pattern included patients with Parkinsoni an tremor, essential tremor type B (with alternating activity), rubral, and psychogenic tremors. Our results revealed that electromyographic examinati on of tremor pattern, frequency, amplitude, and burst duration is useful fo r tremor differentiation. Conclusion: The electromyographic examination may serve as a tool for diffe rentiation of tremors. (C) 2001 Elsevier Science Ireland Ltd. All rights re served.