DENATURED MUSCLE GRAFTS FOR NERVE REPAIR IN AN EXPERIMENTAL-MODEL OF NERVE DAMAGE IN LEPROSY .1. A FUNCTIONAL AND MORPHOMETRIC STUDY

The effectiveness of denatured autologous muscle grafts for nerve repa ir in an experimental model of leprosy was assessed. Nerve damage rese mbling that caused by Mycobacterium leprae in humans was induced by th e injection of cobalt-irradiated M. leprae into the tibial nerve of gu inea pigs. At the time of maximum functional loss, caused by the forma tion of a granuloma within the nerve, the area of damage was excised a nd a denatured autologous muscle graft was used to repair the nerve. A ssessment of nerve regeneration through the graft was made using clini cal, electrophysiological and microscopic morphometric analysis at int ervals up to 20 weeks. The results were compared with regeneration aft er grafting of a normal nerve. Clinically, some motor and sensory reco very occurred in all of the graft recipients in the normal nerve by 8 weeks, and by 11 weeks in the recipients of grafts in the granulomatou s nerve. Full sensory recovery occurred in all but one animal by 20 we eks. Motor function recovered to near normal levels at 14 weeks after repair of the normal nerve but, at 20 weeks, there was variation in mo tor recovery after repair of the granulomatous nerve. Electrophysiolog y showed increased conduction velocity of the nerve fibers at each tim epoint. The conduction velocity at 8 weeks after grafting of the norma l nerve was similar to that at 12 weeks after grafting of the granulom atous nerve. Morphometry showed an increasing number of myelinated fib ers repopulating the distal nerve up to 20 weeks. Myelin fiber numbers , at this time, were one third of normal after repair of the granuloma tous nerve and two thirds after repair of the normal nerve. This study demonstrates that denatured autologous muscle grafts enable the regen eration and functional recovery of nerves despite their being damaged by mycobacteria-induced granulomas, but the damage causes some delay.