Effect of Ethyl Chloride Spray on the Needle Electromyography Result

J Korean Assoc EMG Electrodiagn Med 2009;11(2):110-114.
Published online December 31, 2009.

Abstract

Objective: To assess the effect of the ethyl chloride spray on motor unit action potential (MUAP) morphologyto the needling area who undergoes needle electromyography.
Methods: Twenty examinees were enrolled to see the effect of the variability of the motor unit actionpotentials during needle electromyography (EMG). After needle insertion in biceps brachii muscle, examineescontracted the muscle and quantitative electromyography motor unit action potentials were analyzed.After being analyzed, the ethyl chloride was sprayed over the site of needle insertion and thenquantitative electromyography was carried out again.
Results: Quantitative electromyography showed that the amplitude and phase were not changed in allexaminee after ethyl chloride spraying. However the duration was elongated with significant statisticaldifference.
Conclusions: Our results suggest that ethyl chloride spraying before needle EMG study could changeMUAP duration parameters. So, we must consider such changes in analyzing needle EMG result whenusing ethyl chloride spraying

Key Words: Ethyl chloride, Electromyography, Motor unit action potentials