An experimental study of nerve bypass graft.

ABSTRACT

OBJECTIVE: To study the use of a nerve ''bypass'' graft as a possible alternative to neurolysis or segmental resection with interposition grafting in the treatment of neuroma-in-continuity. METHODS: A sciatic nerve crush injury model was established in the Sprague-Dawley rat by compression with a straight hemostatic forceps. Epineurial windows were created proximal and distal to the injury site. An 8-mm segment of radial nerve was harvested and coaptated to the sciatic nerve at the epineurial window sites proximal and distal to the compressed segment (bypass group). A sciatic nerve crush injury without bypass served as a control. Nerve conduction studies were performed over an 8-week period. Sciatic nerves were then harvested and studied under transmission electron microscopy. Myelinated axon counts were obtained. RESULTS: Nerve conduction velocity was significantly faster in the bypass group than in the control group at 8 weeks (63.57 m/s+/-5.83 m/s vs. 54.88 m/s+/-4.79 m/s, P<0.01). Myelinated axon counts in distal segments were found more in the experimental sciatic nerve than in the control sciatic nerve. Significant axonal growth was noted in the bypass nerve segment itself. CONCLUSION: Nerve bypass may serve to augment peripheral axonal growth while avoiding further loss of the native nerve.