Nerve transfers for axillary nerve repair in brachial plexus injuries: results from 206 patients

Restoration of axillary nerve function is one of the main priorities of brachial plexus surgery. Neurotization, the transfer of a functional but less important donor nerve to a nonfunctional, more important recipient nerve, has become a leading treatment option. A variety of donor nerves, from different segmental levels of the spinal cord, have been used to reinnervate the axillary nerve. This study aimed to describe the clinical results of commonly used donor nerves. A group of 206 patients with a minimum follow-up period of 24 months was analyzed. Axillary nerve injuries were part of C5-6 injuries in 68 patients, C5-7 injuries in 61 patients, and complete injuries in 55 patients. Twenty-two patients had an isolated axillary nerve injury. The median age was 31 years, and the median time between trauma and surgery was 6 months. The following were used as donor nerves: the thoracodorsal nerve in 69 patients, triceps branch of the radial nerve in 25 patients, lower subscapular nerve in 19 patients, long thoracic nerve in 38 patients, intercostal nerves in 27 patients, and fascicle transfer from the ulnar or median nerve in 23 patients. Successful deltoid recovery was defined as a Medical Research Council grade above 3, electromyographic signs of reinnervation, and an increase in deltoid muscle mass. The overall success rate was 60.19% but varied greatly between different types of brachial plexus injuries and available donors. Upper brachial plexus injuries had a success rate of 75.0%, C5-7 injuries had a rate of 65.5%, and complete injuries had a rate of 29.0%. Patients with isolated axillary nerve injuries had a success rate of 77.27%. Donor nerves with the highest success rate were the triceps branch of the radial nerve (80%), followed by the subscapular nerve (78.9%), fascicle transfer from the ulnar or median nerve (73.9%), and thoracodorsal nerve (71.1%). Lower success rates were associated with the long thoracic nerve (36%) and intercostal nerves (29.6%). The authors conclude that nerve transfers can be effective treatment options for axillary nerve injuries. Knowing the potential success rates of the less used donor nerves, i.e., from different segmental levels of the spinal cord, is of utmost importance, especially for extensive brachial plexus injuries.