Spinal Accessory Nerve Duplication – A Rare Anatomical Consternation During Neck Dissectio

Prevention of the spinal accessory nerve (SAN) is an indispensable aspect of the functional neck dissection surgery to avoid highly disabling shoulder syndrome postoperatively. This requires comprehensive knowledge of the anatomy of SAN and its variations. Rare anatomical variations like SAN duplication can result in an inadvertant injury to the SAN. We report a case of duplication of SAN, which was encountered while doing a functional neck dissection surgery for oral squamous cell carcinoma. No iatrogenic injury occurred during the surgery and neither there was any SAN dysfunction post-operatively. Meticulous dissection and consistent identification of SAN, along with vast anatomical knowledge is the key to the preservation of the nerve during the surgery. This report aims to broaden our anatomical knowledge of SAN and also discuss the clinical implications and literature pertaining to the duplication of SAN.

Pathological findings identified during the posterior approach to the spinal accessory nerve after high-energy trauma

The spinal accessory to suprascapular nerve transfer is a key procedure for restoring shoulder function in upper brachial plexus injuries and is typically undertaken via an anterior approach. The anterior approach may miss injury to the suprascapular nerve about the suprascapular notch, which may explain why functional outcomes are often limited. In 2014 we adopted a posterior approach to enable better visualization of the suprascapular nerve at the notch. Over the next 6 years we have used this approach for 20 explorations after high-energy trauma. In 7/20 we identified abnormalities at the level of the suprascapular ligament, which we would not have identified with an anterior approach: there were two ruptures, two neuromas-in-continuity and three cases of scar encasement, necessitating neurolysis. Nerve transfer could be undertaken distal to the suprascapular notch, bypassing the site of injury. These pathological findings support the wider adoption of the posterior approach in cases of high-energy trauma. Level of evidence: IV

Nerve Transfers to Recover External Rotation of the Shoulder after Brachial Plexus Injuries in Adults

Restoration of external rotation of the shoulder in adults with partial brachial plexus palsies is challenging. While nerve grafts are possible, nerve transfers are currently the most use method for satisfactory restoration of function. Numerous nerve transfers have been described, although the transfer of the spinal accessory nerve to the suprascapular nerve remains the gold standard. The suprascapular nerve and the nerve to the teres minor muscle are the two preferred targets to restore external rotation of the shoulder. There are numerous nerve donors, but their use obviously depends on the initial injury. The most common donors are the spinal accessory nerve, the rhomboid nerve, branches of the radial nerve, the C7 root fascicle or the ulnar nerve. The choice for the transfer depends on the available nerves and first of all on chosen approach, whether it be cervical or scapular. It also depends on the other associated reconstruction procedures, grafts, or nerve transfers for the recovery of other functions, specifically, elevation of the shoulder and flexion of the elbow. The objective of this chapter is to present the main nerve transfers and to propose a therapeutic strategy.