Spinal Accessory Neuropathy following Dual Tunneling of Lead Extensions for Motor Cortex Stimulation

Abstract

Background: Spinal accessory nerve (SAN) injury is a known complication of surgery involving the posterior cervical triangle. Because the nerve lies in a plane that is traversed by extension leads for neuromodulation, the SAN is at risk during tunneling for these procedures. Methods: We report a 50-year-old man who developed spinal accessory neuropathy after tunneling of two sets of extension leads through his neck to connect to the pulse generator at the chest wall. Immediately postoperatively, he developed severe right shoulder pain and trapezius weakness manifested as decreased shoulder abduction and scapular winging. Results: Electromyography 2 months later confirmed a SAN injury. Ultrasonography demonstrated the SAN to be angulated between the two sets of extension leads in the posterior cervical triangle. Operative exploration confirmed this finding. Neurolysis was performed and the deep extension lead was relocated superficial to the nerve. Postoperatively, the patient had immediate resolution of his shoulder pain and an improved range of motion. Conclusion: As the indications for neuromodulation continue to grow, tunneling may be performed more frequently. It is our belief that the second pass through the neck of a dual extension lead system may inadvertently be directed deeply and poses an increased risk to the SAN.

Role of Sonography in Surgical Decision Making for Iatrogenic Spinal Accessory Nerve Injuries

“…Although the risk of iatrogenic SAN injury is highest with radical neck dissection, occurring in 50% to 70% of cases, 5 , 6 it is most commonly associated with cervical lymph node biopsy, affecting 3% to 6% of patients 3 – 10 . Spinal accessory nerve injury has also been reported after carotid endarterectomy, cervicofacial lifts, 4 , 11 tunneling of neuromodulation wires, 12 and direct trauma to the posterior neck. Presumed injury mechanisms include compression, 13 , 14 stretch/traction, 4 thermal injury, and transection (being noted in 70%–87.5% of cases requiring surgical explorations) 4 , 8 , 15 , 16 …”