Electromyographic differentiation of tremors

Objective: The aim of this study was to explore the opportunity for differentiation of tremors on the basis of the electromyographic examination. Methods: We report data from 525 patients with different types of tremor included 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 physiological tremor due to anxiety, and 29 patients with psychogenic tremor participated in the study. A detailed neurological and electromyographic examination was performed. The tremor was studied in all limbs positions. Surface electromyographic recordings of the most involved body part were performed to all patients. Results: According to the electromyographic examination all patients were divided to two groups: Patients with synchronous tremor and patients with alternating tremor in the antagonist muscles. The comparisons were performed only between the patients with tremor caused by different etiology within the group of synchronous or alternating tremor. The group of tremors with synchronous 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 Parkinsonian tremor, essential tremor type B (with alternating activity), rubral, and psychogenic tremors. Our results revealed that electromyographic examination of tremor pattern, frequency, amplitude, and burst duration is useful for tremor differentiation. Conclusion: The electromyographic examination may serve as a tool for differentiation of tremors. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.