An experiment study on the limit of fascicular harvest in partial nerve transfer in treatment of brachial plexus root injuries

Objective To investigate the largest harvestable portion of the unlar nerve without causing limb functional deficit for partial fascicle nerve transfer.Matheds 120 Wister rats were used.Different portions of the ulnar nerve (1/6,1/3,1/2,2/3,and entire nerve) were cut at the level where the musculocutaneous nerve enters the biceps brachia.After 6 to 8 weeks behavioral test,electrophysiologic test,muscle weight measurement of flexor carpi ulnaris and abductor digiti minimi manus,and ultrastructural observation were carried out.Results When less than 1/3 of the ulnar nerve is cut,functional deficit could return to normal within a short period of time.When 1/3 to 1/2 of the aerve fascicles were cut,more obvious functional deficits were noted with a prolonged recovery time and some irreversible changes.When more than 2/3 of the ulnar nerve was cut,severe irreversible functional loss occurred. Conclusion Harvesting less than 1/3 fascicles of the ulnar nerve at the upper arm level is relatively safe.However, caution mast be used when consider taking more than 1/2 of the nerve in that severe and irreversible functional deficit cam occur.