Modified Dorsal Approach for Spinal Accessory Nerve (SAN) to Suprascapular Nerve (SSN) Transfer

Sir, One of the primary goals in the rehabilitation of patients with pan or partial upper brachial plexus injury (BPI) is attainment of shoulder stability and function. Suprascapular nerve (SSN) and axillary nerve play the main role in shoulder function and hence are preferentially targeted during restoration surgery for BPI.[1] Currently, there are two approaches for transferring spinal accessory nerve (SAN) to SSN; anterior and posterior approaches. Proponents of posterior or dorsal approach suggest that it leads to minimal denervation of upper and middle trapezius fibers and is cosmetically better as compared to traditional anterior approach. Dorsal approach also leads to earlier recovery of function due to nerve anastomosis closer to the target muscle.[2] Traditional dorsal approach for SAN to SSN transfer involves identifying the SSN at suprascapular notch and delineation of nerve followed by division of SSN just proximal to the notch.[3] This leaves us with a relatively short segment of SSN for anastomosis with distal SAN, potentially leading to neurotization under tension which might lead to delayed and poor nerve regeneration. Also, the surgeon has to perform the nerve anastomosis at a greater depth owing to the shorter recipient length. We appreciate the author Guan et al.[3] on their described dorsal approach surgical technique, although we would like to propose a novel modification to the traditional dorsal approach for SAN to SSN transfer [Figures 1 and 2]. Our technique involves additional division of the inferior belly of omohyoid muscle which provides access to the whole length of SSN from its origin, i.e. Erb’s point to the suprascapular notch. By doing so, the available length of SSN is being doubled; this ensures tension-free anastomosis as anastomosis is done at more optimal depth, which is paramount for a successful outcome. Moreover it allows the inspection of the whole length of recipient SSN from its origin to insertion in order to rule out a distal neuroma in post-ganglionic injuries.Figure 1: (a) Schematic diagram showing right anterior neck and relation of SAN and SSN with inferior belly of omohyoid muscle. (b) Representative clinical photo. (c) Schematic diagram showing right shoulder and back with bony relation of SAN and SSN to scapulaFigure 2: Intraoperative pictures of modified dorsal SAN to SSN transfer. (a) Suprascapular ligament divided; SSN and Inferior belly of omohyoid identified. (b) Inferior belly of omohyoid is coagulated and divided. (c) SSN visualized from Erb’s point to suprascapular notch. (d) SAN identified and delineated. (e) SAN and SSN were divided and prepared for anastomosis. (f) SAN to SSN tension-free nerve transfer done with 10-0 nylonFinancial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.