In this experiment, authors observed conduction disturbance of the afferent sensory nerve fibers from the sciatic nerve by percussion injury and effect of neurolysis that relieve the axonal compression. Under the operating microscope, a longitudinal neurolysis approximately 2 to 3 cm in length was made at the injury site 30 minutes and 2 hours after injury.
1. There were main 4 component waves of dorsal root evoked potentials in control group. The mean conduction velocity of N1 was 62.4 ± 0.10 m/sec, N2 was 29.9 ± 0.25 m/sec, N3 was 19.92 ± 0.27 m/sec, and N4 was 14.75 ± 0.51 m/sec, N1 belonged to A alpha, N2 to A beta, and N3 & N4 to A delta group.
2. In the potentials of L5 and L6 these component waves were typical and the amplitudes were the largest, which meant that L5 and L6 were main pathway of the sciatic afferent fibers.
3. In control group, the latency of root potential was little changed. The amplitude of root potential was decreased 62-69%, except N1.
4. By percussion injury the latency was prolonged. The latencies of N1 and N2 was increased and those of N3 and N4 was little changed, compared with control group.
5. By percussion injury the amplitudes of N1 and N2 showed 78.6% decrease and 68.0% decrease and the those of N3 and N4 showed 48.3% and 22.0% decrease which was not significant comparing with control group.
6 To relieve the periaxonal compression, neurolysis was done. Improvement of the conduction by neurolysis was prominent in N1 and N2 but hardly appeared in N3 and N4.
7. The decrease of amplitude due to injury was diminished by neurolysis in N1 and N2. But in N3 and N4 there was scarcely any effect.
8. The effect of neurolysis was appeared when it operated within 30 minutes but not appeared after 2 hours operation.
Summarizing these results it was suggested the conduction of A fibers by percussion injury was disturbed and its mechanism due to periaxonal edema, because conduction of A alpha was slowed and relieved by neurolysis. And A delta fiver was unaffected by percussion injury but changed along the course of time and then it was suggested there were other factors affecting conduction of peripheral nerve.
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