Spinal Accessory Nerve Injury in Patients with Brachial Plexus Injury: Prevalence, Predisposing Factors, and Spontaneous Recovery.

Abstract

The spinal accessory nerve is occasionally injured during brachial plexus injuries, potentially limiting its use as a donor motor nerve for reconstructive surgery. Assessing spinal accessory nerve function preoperatively is essential to optimize outcomes in brachial plexus reconstruction. The authors examined the demographics of spinal accessory nerve injury, focusing on its prevalence, predisposing factors, and potential for spontaneous recovery in patients with brachial plexus injuries. A total of 170 patients were included in this study. At the first visit, the spinal accessory nerve function was assessed by measuring the compound muscle action potential of the upper trapezius muscle. The function of the nerve was classified as follows: no injury (amplitude of the potential ≥50% compared with the unaffected side), partial injury (amplitude <50%), and severe injury (absence of the potential). For the evaluation of spontaneous recovery, patients with partial and severe injuries underwent further assessment at 1 year after the injury and at the final follow-up. The authors found the associated spinal accessory nerve injury in 30 patients (17.6%) (partial, 17; severe, 13). Spinal accessory injury occurred in 13 of 39 patients with phrenic nerve palsy (33.3%). Phrenic nerve palsy may serve as a predisposing factor for this injury. In 18 patients followed up for more than 1 year, 15 (83.3%) showed good spontaneous recovery. Spinal accessory nerve injury occurred in approximately 18% of patients with brachial plexus injuries. Most cases of spinal accessory nerve injury associated with brachial plexus injury have a potential for good spontaneous recovery.