[Electrophysiologic and histopathologic evaluation of peripheral nerve regeneration at different nerve segments and...

We compared the electrophysiologic and histopathologic results of early primary nerve repair and grafting of transections made at different levels.

Twenty-two male Sprague-Dawley rats were divided into three groups. In one group (distal group, n=8), the right sciatic nerve was transected near the proximal segment of, and in another (proximal group, n=7) at 15 mm proximal to, its branching. In the graft group (n=7), the nerve was resected from 5 mm to 15 mm proximal to its branching and the defect was repaired with the removed segment. All the nerves were repaired using the epiperineural technique. Electrophysiologic studies were performed before and after surgery. In the third month, bilateral biopsies were taken from the L4-5 dorsal root ganglion and from distal nerve segments for histopathologic examination and neuron and axon counts.

At two months, the distal group exhibited significantly shorter latency (p=0.001) and higher amplitude (p=0.05) values. However, at three months, all the groups had similar values of latency, amplitude, and conduction velocity. At three months, the number of the dorsal root ganglion neurons was significantly greater in the distal group compared to the graft group (p<0.001), but this did not differ from the proximal group (p>0.05). Axon counts per square millimeter were similar (p>0.05), but axon diameter was greater in the distal group (p<0.05). In correlation analyses, increases in the number of L4-5 dorsal root ganglion neurons were significantly associated with increases in the percent changes in distal latency (p<0.05) and conduction velocity (p=0.018).

Our findings suggest that distal injuries and primary repair of the sciatic nerve result in a faster and better recovery.