Pectoral nerve conduction studies: technique in healthy subjects and evaluation of brachial plexopathy.

Abstract

To define the optimal nerve conduction study (NCS) technique of the pectoral nerves and evaluate its clinical utility. Prospective electrophysiologic study with healthy controls. Electrophysiologic laboratory in a large general hospital. Thirty healthy controls and 10 patients with cervical root or brachial plexus pathologies. Not applicable. Correlation of pectoral NCS with electromyography and magnetic resonance imaging. For pectoral NCS, the mean values +/- standard deviation of onset latency, amplitude, and interside amplitude ratio (ratio of smaller over larger amplitude) were 2.01+/-0.22 ms, 11.75+/-2.21 mV, and .95+/-.04 mV, respectively. Subject age correlated significantly with both onset latency (r=.46, P<.001) and amplitude (r=-.34, P<.008). All 5 patients with brachial plexopathy had amplitude ratios below the normal limit of controls (.87). However, this was not seen for all 5 patients with cervical spondylotic radiculopathy. The pectoral NCS technique is feasible in healthy subjects. It is useful when differentiating brachial plexopathy from cervical root lesions.