Science News: Spinal Accessory Nerve Versus Intercostal Nerves in Gracilis Free-Functioning Muscle Transfer for Elbow Flexion in Adult Brachial Plexus Patients

Submitted by: Rebecca O'Bryan, MD
Citation: Bhat SG, Bishop AT, Spinner RJ, Kaufman KR, Shin AY. Spinal Accessory Nerve Versus Intercostal Nerves in Gracilis Free-Functioning Muscle Transfer for Elbow Flexion in Adult Brachial Plexus Patients. J Hand Surg Am. 2025;50(7):837-845. doi:10.1016/j.jhsa.2025.04.005

Summary: This study investigated 22 patients who underwent free-functioning muscle transfer (FFMT) for traumatic brachial plexus injury for surgical reconstruction of elbow flexion. The aim of the study was to compare differences in voluntary neuromuscular control of the FFMT gracilis reinnervated by either the spinal accessory nerve (SAN) or intercostal nerves (ICN). Patients were recruited postoperatively for follow up. Exclusion criteria were less than 6 months from surgery and or alternative donor nerves used. 12 patients had SAN reinnervation while 10 had ICN (8 with 2 ICN and 2 with 3 ICN). SAN group was significantly closer to their surgery and therefore a z score was calculated for this variable and used as a covariate. ICN group showed greater strength and range of motion. Contraction latency was similar. The SAN group had better relaxation latency. Hold times were similar, but SAN group showed modulation of hold times with an increase in percent maximum torque. Conclusions were that the SAN group showed a better ability to relax elbow flexion produced by the gracilis muscle compared with the ICN group. The SAN group also demonstrated better modulation in their hold times with an increase in torque demand compared with the ICN group.

Comments: This is a very interesting study looking at FFMT of gracilis for restoration of elbow flexion in pan-plexopathy BPI patients. The SAN is a voluntary motor nerve while ICNs are mixed postural nerves that provide involuntary postural and voluntary breathing functions. This study seems to indicate more natural restoration of voluntary elbow contraction, which is very important to consider with this procedure. Unfortunately the SAN is not always available for donation, and the ICN does seem to provide adequate function as well if needed. This study is very small in terms of sample sizes, and has its limitations, but is helpful to us as neuromuscular specialists in terms of considerations of our surgical colleagues. Ensuring normal function of the SAN during electrodiagnostic study of these patients may be very beneficial to the surgical team.

Why is this article interesting/relevant to the AANEM audience? As noted in the comments above, this study is helpful to us as neuromuscular specialists in terms of considerations of our surgical colleagues. Ensuring normal function of the SAN during electrodiagnostic study of these patients may be very beneficial to the surgical team.