Following injury to the tibial nerve in rabbits, changes in the motor nerve conduction velocity and the latency of somatosensory evoked potential were observed and compared. The extent of local pressure injury was 0.29 kg/cm2 in the first group, 2.06 kg/cm2 in the second group, and 4.66 k g/cm2 in the third group.
1) Following application of various degree of local pressure, motor nerve conduction velocity was lowest at the second week postoperatively in all the groups.
Reduction of motor nerve conduction velocity was most remarkable between the third and seventh postoperative hour in both the second and the third groups. It was observed that the higher the pressure applied, the sooner the motor nerve conduction velocity dropped.
2) At the sixteenth postoperative week, the mean rate of recovery of the motor nerve conduction velocity was 95. 0% in the f?rst group, 71.0´o in the second group, and 40.5% in the third group. It was observed that the higher the pressure applied, the less the motor nerve conduction velocity recovered.
The mean starting time of recovery of motor nerve conduction velocity was 3.1´ weeks postoperatively in the first group, 6.5 weeks postoperatively in the second group, and 10.0 weeks postoperatively in the third group. It was observed that the higher the pressure applied, the later the motor nerve conduction velocity recovered.
3) Following application of various degrees of local pressure, increase in the latency of somatosensory evoked potential was most remarkable between the first and sixth postoperative hours in the first group, but in the first postoperative hour in both the second and the third groups. It was observed that the higher the pressure applied, the sooner the latency of somatosensory evoked potential increased.
4) At the sixteenth postoperative week, the mean rate of increase of the latency of somatosensory evoked potential was 105.0°6 in the first group, 118.6°a in the second group,
and 180.4% in the third group. It was observed that the higher the pressure applied, the less the latency of somatosensory evoked potential recovered.
5) In the regeneration phase, the latency of somatosensory evoked potential showed earrlier recovery than the motor nerve conduction velocity+ in all the groups, by 1.8 weeks in the first group, 4.4 weeks in the second group, and 8.6 weeks in the third group. It is
suggested that the somatosensory evoked potential test is valuable in the early detection of peripheral nerve regeneration.
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