Vasculogenic Myoclonus of Peripheral Origin after Whiplash Injury: A Case Report

Abstract

Based on the neuroanatomical origin of the electrical discharge, myoclonus could be classified in terms of its etiology as cortical, subcortical, spinal, or peripheral. A 29-year-old female patient experienced a continuous involuntary rhythmic twitching movement of the right elbow for 6 months. This myoclonus occurred immediately after a whiplash injury caused by a rear-end car accident. The patient had no radiological, clinical, or electrophysiological evidence for central nervous system origin. Concentric needle electromyography recordings of the right biceps, brachioradialis, and triceps muscles presented bursts of spontaneous rhythmic activity synchronous to the clinical myoclonus. Doppler ultrasound on the right arm revealed that the biceps and triceps contraction coincided with the vascular pulsation of the brachial artery and vein. This result suggested that myoclonus was caused by vascular stimulation, similar to the pathophysiology of hemifacial spasms. A whiplash injury around the neck or arm may have affected the vascular structures in the upper and middle trunks, resulting in vasculogenic myoclonus. Electromyography can be used to determine the classification and distribution of myoclonic jerks.