Reconstruction of the spinal accessory nerve with selective fascicular nerve transfer of the upper trunk.

Abstract

Spinal accessory nerve palsy is frequently caused by iatrogenic damage during neck surgery in the posterior triangle of the neck. Due to late presentation, treatment regularly necessitates nerve grafts, which often results in a poor outcome of trapezius function due to long regeneration distances. Here, the authors report a distal nerve transfer using fascicles of the upper trunk related to axillary nerve function for reinnervation of the trapezius muscle. Five cases are presented in which accessory nerve lesions were reconstructed using selective fascicular nerve transfers from the upper trunk of the brachial plexus. Outcomes were assessed at 20 ± 6 months (mean ± SD) after surgery, and active range of motion and pain levels using the visual analog scale were documented. All 5 patients regained good to excellent trapezius function (3 patients had grade M5, 2 patients had grade M4). The mean active range of motion in shoulder abduction improved from 55° ± 18° before to 151° ± 37° after nerve reconstruction. In all patients, unrestricted shoulder arm movement was restored with loss of scapular winging when abducting the arm. Average pain levels decreased from 6.8 to 0.8 on the visual analog scale and subsided in 4 of 5 patients. Restoration of spinal accessory nerve function with selective fascicle transfers related to axillary nerve function from the upper trunk of the brachial plexus is a good and intuitive option for patients who do not qualify for primary nerve repair or present with a spontaneous idiopathic palsy. This concept circumvents the problem of long regeneration distances with direct nerve repair and has the advantage of cognitive synergy to the target function of shoulder movement.