Use of muscle-vein-combined Y-chambers for repair of multiple nerve lesions: experimental results.

Y-shaped vein conduits enriched with fresh skeletal muscle fibers were used to bridge a concomitant ulnar and median nerve transection with substance loss in rats. The proximal limb of the Y-chamber was sutured to the proximal ulnar nerve, while the two distal limbs were sutured to ulnar and median distal nerve stumps. Eight months after surgery, median nerve functional recovery was evaluated by means of the grasping test, and nerve fiber regeneration in both repaired nerves was assessed by means of design-based histomorphometry. Results showed that nerve fibers regenerated along both severed nerve trunks, and in the median nerve led to a recovery corresponding to 58% of normal nerve function. Quantitative analysis showed no significant morphological differences between myelinated nerve fibers regenerated along the two distal nerves except for the number of fibers, which was higher in the median nerve. Notably, the total number of regenerated nerve fibers in the two distal nerves was 4-fold the normal fiber number in the ulnar nerve. Besides their interest in relation to the long-lasting debate about the topographic specificity of nerve regeneration, the results of this study show an effective way to repair, in the rat experimental model, two transected nerve trunks innervating agonistic muscles in the case that the proximal stump of only one nerve is preserved.