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Electrophysiological testing of spinal accessory nerve in suspected cases of nerve transection
Author(s) -
Laughlin Ruple S.,
Spinner Robert J.,
Daube Jasper R.
Publication year - 2011
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.22135
Subject(s) - medicine , compound muscle action potential , electromyography , electrophysiology , accessory nerve , anesthesia , surgery , motor unit , nerve injury , anatomy , physical medicine and rehabilitation
In this study we sought to determine whether standard electrophysiological testing of the spinal accessory nerve (SAN) accurately identifies patients who would benefit from surgical repair. Methods: Sixteen consecutive patients sent for surgical evaluation of unilateral SAN injury were studied clinically and electrophysiologically. Results: All patients demonstrated a low‐amplitude SAN compound muscle action potential (CMAP) that required a higher stimulus intensity to obtain it than on the unaffected side. Upper trapezius needle electromyography showed dense fibrillation potentials in 16 of 16 nerves, with voluntary motor unit potentials (MUPs) in 5 of 16. Intraoperatively, 12 of 16 nerves were transected; 4 of 16 had neuromas across which there was no nerve action potential. Patients underwent direct repair (6 of 16) or interpositional nerve grafting (10 of 16). Fourteen of 15 patients seen postoperatively had improvement in pain, muscle bulk, and range of motion. Conclusions: Surgical exploration of the SAN is warranted in patients with clinical signs of severe injury, even when electrophysiological testing shows low‐amplitude CMAPs and/or residual MUPs. Muscle Nerve, 2011