There is no standard electrodiagnostic method of measuring the intercostal nerve conduction in man. The purpose of this study was to establish the standard electrodiagnostic method for intercostal nerve conduction. We studied compound muscle action potentials (CMAP) of rectus abdominis and spinal evoked potentials at the T6 spinous process level with surface recording electrodes to lower intercostal nerve stimulations.

Thirty healthy men at 3rd decade were studied.

The results were as follows;

1) The mean value of distal latency of CMAP was 3.54±0.49 msec to the 7th intercostal nerve, 4.50±0.51 msec to the 9th intercostal nerve, and 5.41±0.70 msec to the 11th intercostal nerve stimulation.

2) The mean value of amplitude and area of CMAP was 7.85±3.55 mV and 34.52±18.75mV·msec to the 7th intercostal nerve, 3.55±1.73 mV and 19.01±9.68 mV·msec to the 9th intercostal nerve, and 3.11±2.97 mV and 21.16±19.38 mV·msec to the 11th intercostal nerve stimulations, respectively.

3) The mean value of conduction velocity was 69.23±7.19 m/sec in the 7th intercostal nerve, 71.22±10.12 m/sec in the 9th intercostal nerve, and 74.15±10.71 m/sec in the 11th intercostal nerve.

4) The mean value of N1 latency and amplitude of spinal evoked potential was 4.05±0.38 msec and 2.87±2.99㎶ to the 7th intercostal nerve, 5.03±0.53 msec and 1.88±0.79㎶ to the 9th intercostal nerve, and 5.78±0.70 msec and 1.96±1.48㎶ to the 11th intercostal nerve stimulation, respectively.

From the above results, these electrodiagnostic methods for lower intercostal nerves can be useful technique clinically.