Repair of the peripheral nerve gap with epineural sheath conduit to prevent muscle denervation atrophy in the diabetic rat model.

UNLABELLED Muscle denervation atrophy is a result of lower motor neuron injury, thus an early restitution of muscle stimulation is essential in prevention of atrophic changes. THE AIM OF THE STUDY To evaluate the new application of naturally occurring epineural sheath conduit in repair of the peripheral nerve gap to prevent development of muscle denervation atrophy. MATERIAL AND METHODS We used the model of 20 mm sciatic nerve gap, resulting in denervation atrophy of the gastrocnemius muscle in the diabetic rats (DM type 2, n=42, Zucker Diabetic Fatty strain). We applied the epineural sheath conduit created from the autologous sciatic nerve for gap repair. Muscle atrophy was assessed with the Gastrocnemius Muscle Index (GMI) and microscopic muscle morphometry (mean fiber area) at 6 and 12 postoperative week. Muscle regeneration in the experimental group was compared to the gold-standard technique of autologous nerve grafting for the repair of created nerve gap. RESULTS The GMI evaluation revealed comparable muscle mass restoration in groups with nerve repair using both epineural sheath and standard autologous nerve grafting (reaching 28 and 35% of contralateral muscle mass at 12 postoperative week, respectively, p=0.1), and significantly better restoration when compared to the negative control group (no repair, 20%, p<0.01). Micromorphometry confirmed significantly larger area of the regenerated muscle fibers in groups with both nerve grafting and epineural sheath conduit repair (reaching for both ca. 42% of the non-operated side), when compared to severe atrophic outcome when no nerve repair was performed (14% of the control fiber area, p<0.0001). The effectiveness of epineural conduit technique in muscle mass restoration was observed between 6 and 12 weeks after nerve repair--when gastrocnemius muscle mass increased by 12%. CONCLUSIONS Peripheral nerve gap repair with naturally occurring epineural sheath conduit is effective in prevention of muscle denervation atrophy. This method is applicable in diabetic model conditions, showing results of regeneration which are comparable to the autologous nerve graft repair.