Active shoulder external rotation recovery in upper brachial plexus birth injury following nerve surgery: is spinal accessory nerve-suprascapular nerve transfer superior to C5-suprascapular nerve grafting?

OBJECTIVE A key residual deficit in brachial plexus birth injury (BPBI) is the lack of active glenohumeral external rotation (ER). Surgical options for reinnervating the suprascapular nerve (SSN) include nerve grafting from a proximal stump and nerve transfer using the spinal accessory nerve (XIN) as a donor. The optimal surgical strategy is unclear from the current literature. This study aimed to compare the outcomes of nerve grafting and nerve transfer for SSN reinnervation in upper trunk BPBI.

METHODS The authors conducted a retrospective study (1990-2020) on prospectively collected data of children with a C5-6 or C5-C6-partial C7 BPBI who underwent SSN grafting or transfer, with a minimum follow-up of 2 years. Outcome was assessed in degrees of active ER and Mallet subscores for hand-to-mouth reach, hand-to-head reach, and ER. The frequency of secondary shoulder procedures (tendon transfer and/or anterior release) in both groups was also analyzed.

RESULTS The study included 245 patients with a mean follow-up of 7.6 ± 4.3 years: 179 (73%) underwent C5-SSN grafting and 66 (27%) XIN-SSN transfer. The nerve transfer group demonstrated an active range of ER that was 30° (95% CI 12°-49°, p = 0.002) larger than that of the nerve grafting group, adjusted for sex, birth weight, and diagnosis. At age 3 years, 33% of children achieved Mallet score IV ER after nerve transfer compared with 17% after nerve grafting (p = 0.002). Hand-to-mouth and hand-to-head scores were similar between the groups. The 10-year cumulative risk of subsequent shoulder procedures was 30% (95% CI 23%-37%) for nerve grafting and 24% (95% CI 13%-35%) for nerve transfer (nonsignificant).

CONCLUSIONS XIN-SSN transfer results in superior active ER compared to nerve grafting. Future studies should investigate whether the long-term impact of trapezius muscle loss is acceptable, to determine whether nerve transfer should be prioritized over grafting in the presence of a graftable C5 root.