Improved C(3-4) transfer for treatment of root avulsion of the brachial plexus upper trunk: Animal experiments and clinical application☆

Experimental rats with root avulsion of the brachial plexus upper trunk were treated with the improved C(3-4) transfer for neurotization of C(5-6). Results showed that Terzis grooming test scores were significantly increased at 6 months after treatment, the latency of C(5-6) motor evoked potential was gradually shortened, and the amplitude was gradually increased. The rate of C(3) instead of C(5) and the C(4) + phrenic nerve instead of C(6) myelinated nerve fibers crossing through the anastomotic stoma was approximately 80%. Myelinated nerve fibers were arranged loosely but the thickness of the myelin sheath was similar to that of the healthy side. In clinical applications, 39 patients with root avulsion of the brachial plexus upper trunk were followed for 6 months to 4.5 years after treatment using the improved C(3) instead of C(5) nerve root transfer and C(4) nerve root and phrenic nerve instead of C(6) nerve root transfer. Results showed that the strength of the brachial biceps and deltoid muscles recovered to level III–IV, scapular muscle to level III–IV, latissimus dorsi and pectoralis major muscles to above level III, and the brachial triceps muscle to level 0–III. Results showed that the improved C(3-4) transfer for root avulsion of the brachial plexus upper trunk in animal models is similar to clinical findings and that C(3-4) and the phrenic nerve transfer for neurotization of C(5-6) can innervate the avulsed brachial plexus upper trunk and promote the recovery of nerve function in the upper extremity.