Tetraparetic critically ill patients show electrophysiological signs of myopathy.

INTRODUCTION: Critically ill patients often develop tetraparesis. It has been debated whether this is caused by neuropathy, myopathy, or both. The aim was to determine the incidence of myopathy and neuropathy in weak patients in the intensive care unit by performing several electrophysiological examinations, including quantitative electromyography (qEMG). METHODS: Forty-nine patients referred for electrophysiological examination because of suspected critical illness-related weakness underwent qEMG, nerve conduction studies, and direct muscle stimulation. RESULTS: The qEMG showed signs of myopathy in 33 of 35 patients. Direct muscle stimulation was consistent with myopathy in 31 of 34 patients. Amplitudes of compound muscle action potentials were decreased in all patients. Four patients also had signs of sensory neuropathy, which could not be explained by preexisting medical conditions. CONCLUSIONS: When combined, the results are compatible with muscle dysfunction in all patients. This will help to direct future studies of the pathophysiology of this serious condition. Muscle Nerve 56: 433-440, 2017.