A cadaveric feasibility study of modified contralateral C7 transfer permitting ulnar nerve recovery by lateral antebrachial cutaneous nerve

Abstract

Traditional contralateral seventh cervical nerve root (C7) transfer sacrifices the recovery of ulnar nerve. This cadaveric study, done in 20 upper extremities from 10 cadavers, looks at the feasibility of using a modified contralateral C7 transfer using lateral antebrachial cutaneous nerve to allow recovery of ulnar nerve. The deep branch of ulnar nerve was preserved with ipsilateral lateral antebrachial cutaneous nerve, while the distal end of ulnar nerve with its dorsal and superficial branches was transferred to contralateral C7 nerve root and the proximal end of ulnar nerve was anastomosed to both median and musculocutaneous nerves. The ipsilateral lateral antebrachial cutaneous nerve was separated and coapted with motor branch of ulnar nerve. The distance from the midpoint of connection of medial and lateral epicondyles of humerus (interepicondylar line) to the starting point of deep branch of ulnar nerve was significantly shorter than that to the branching point of the lateral antebrachial cutaneous nerve (p < 0.05). The differences in diameters between deep branch of ulnar nerve and main trunk and branches of lateral antebrachial cutaneous nerve were not significant (p > 0.05). The ratio of ulnar nerve axon count to combined total axon count of musculocutaneous nerve, main trunk of lateral antebrachial cutaneous nerve and branches to deep branch of ulnar nerve were above 1:3. In conclusion, the deep branch of ulnar nerve could be restored with lateral antebrachial cutaneous nerve, while contralateral C7 was transferred to median and musculocutaneous nerves through grafts of dorsal and superficial branches of ulnar nerve.