Spinal Accessory Nerve Neuropathies Followng Neck Dissection

Abstract

Objective To evaluate through electromyography (EMG) the injury to the 11th cranial nerve following neck dissection. Methods Prospective study with 60 patients submitted to neck dissection as part of treatment of head and neck tumors. All the cases underwent physiotherapic evaluation of shoulder dysfunction. Nerve integrity was evaluated pre- and postoperatively through surface EMG registering the electric activity of descendent fibers of trapezius muscle during maximal isometric voluntary contraction. The patients were grouped according the type of neck dissection, presence of shoulder pain, impairment during abduction movement, and hypotrophy or atrophy of trapezius muscle. Results The action potential had mean and standard deviation of 61,7±31,6mcV in preoperative evaluation and 15,6±12,4mcV in postoperative evaluation (p<0.001). According to the neck dissection extension, there were mean values of 18,8±14,2mcV after dissection includiog level IIb and 18,8±14,2 mcV after dissection including levels IIb and V (p<0.002). Conclusions Surface EMG is a sensitive and painless for 11th cranial nerve disfunction evaluation. In all cases, the superior fibers of trapezius muscle were affected with presence of pain and impairment abduction movement of the arm. The results suggest the benefit of trapezius muscle EMG to confirm the diagnosis and early physiotherapic intervention in neuropathies of the 11th cranial nerve.