Effects of different methods of peripheral nerve repair on the number and distribution of muscle afferent neurons in rat dorsal root ganglion.

The effects of three methods of peripheral nerve repair and normal controls were compared with respect to the number and distribution of muscle afferent nerve cell bodies from the extensor digitorum longus muscle in the dorsal root ganglia of the rat. Nerves were repaired using one of three methods: 1) direct epineurial suture; 2) a three-strand cable graft; or 3) a coaxially aligned freeze-thawed autologous skeletal muscle graft. In all cases the number and distribution of muscle afferent nerve cells were estimated 300 days after nerve repair. Retrograde transport of horseradish peroxidase, injected into the extensor digitorum longus muscle, was used to identify muscle afferent nerve cell bodies in dorsal root ganglia exposed at laminectomy after fixation. It was found that all methods of nerve repair were associated with a change in both the number and distribution of labeled muscle afferent cell bodies. The number of labeled muscle afferent cells was significantly different from normal controls in all methods of repair, but was not significantly different among the three methods compared. On the other hand, cell size and cell distribution departed significantly more from normal after either of the grafting procedures than after direct repair. There was no significant difference between the two grafting techniques. These results are discussed with respect to their mechanistic and clinical interpretation.