Spinal accessory nerve injury: eight cases and review of the literature.

The spinal accessory nerve (SAN) is the major motor supply to the trapezius and sternocleidomastoid muscles. The superficial course of the SAN in the posterior cervical triangle makes it vulnerable to injuries. The most common reason is an iatrogenic injury during surgery but other causes such as stretch or traction injury have also been reported. Five iatrogenic SAN injuries were occurred after radical neck dissection (RND) for laryngeal carcinoma in two patients, lymphadenectomy for oral mucosal tumor in one patient, surgery for lipoma in one patient, and lymph node biopsy for tuberculosis in one patient, traumatic SAN injuries were occurred after the carrying and lifting in three patients. Our eight patients were followed conservatively and 6 of them had significant improvement of pain and function of the shoulder. However, the remaining two patients with radical neck dissection showed moderate improvement in both pain and function including shoulder range of motion and activities of daily living. We report the eight cases with SAN injury that had admitted to our outpatient clinic in the last one year with neck, back and shoulder pain as well as limitation in the shoulder range of motion and difficulty in the activities of daily living.