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

OBJECTIVE

To define the optimal nerve conduction study (NCS) technique of the pectoral nerves and evaluate its clinical utility.

DESIGN

Prospective electrophysiologic study with healthy controls.

SETTING

Electrophysiologic laboratory in a large general hospital.

PARTICIPANTS

Thirty healthy controls and 10 patients with cervical root or brachial plexus pathologies.

INTERVENTIONS: Not applicable.

MAIN OUTCOME MEASURE: Correlation of pectoral NCS with electromyography and magnetic resonance imaging.

RESULTS

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.

CONCLUSIONS

The pectoral NCS technique is feasible in healthy subjects. It is useful when differentiating brachial plexopathy from cervical root lesions.