DELAY OF THE DENERVATION PROCESS IN SKELETAL-MUSCLE BY SENSORY GANGLION GRAFT AND ITS CLINICAL-APPLICATION

We examined the effects of dorsal root ganglion isografts on the dener vation process of skeletal muscle. A segment of sciatic nerve was remo ved from each of 25 inbred Wistar-Kyoto rats. Fifteen were set aside a s controls. In the remaining 10 rats, isogeneic cervical dorsal root g anglia were grafted to the severed distal stump of the common peroneal nerve. Between day 72 and day 286 postoperatively, both controls and recipients were killed after twitch and tetanic tension recording of t he extensor digitorum longus was performed. The wet muscle weight and the twitch and tetanic tensions of the denervated extensor digitorum l ongus in the graft group were significantly greater than those in the control group. The mean area of the denervated tibialis anterior muscl e fibers in the graft group also was significantly larger than that in the control group. In electron and light microscopic images, nerve ce lls along the periphery of each dorsal root ganglion were found surviv ing with regenerating axons throughout the experimental period. Numero us myelinated axons were observed in the common peroneal nerve of the graft group, and there were significantly more axonal branches in the extensor digitorum longus of the graft group than in the extensor digi torum longus of the control group. Thus sensory nerve fibers from the grafted dorsal root ganglia had certain beneficial effects to slow the denervation process, presumably secreting trophic factors into the de nervated muscle. Clinically, we have transferred avulsed dorsal root g anglia in cases of total brachial plexus avulsion directly into denerv ated skeletal muscle. This procedure, accompanied by nerve crossing pr ocedures, will probably keep denervated skeletal muscle in a better co ndition until regenerating motor axons from the repair site reach thei r target muscle.