Injury of the spinal accessory nerve in posterior cervical triangle may result from a variety of causes. These include direct trauma, compression by lymph node or tumor, spontaneous accessory nerve palsy, and complication from surgical procedures. One of the most valuable method for diagnosis of spinal accessory nerve injury is measurement of its latencies. But we could scarcely find the useful electrodiagnostic data about spinal accessory nerve which was measured in normal subjects in Korea. We measured normal values of spinal accessory nerve latency in 71 volunteers, and clarified the correlation of latency with age, and of latency with conduction distance. Mean latencies of 142 spinal accessory nerves to the upper, middle, and lower trapezius muscles are 2.01±0.31 msec, 3.08±0.46 msec, and 4.54±0.74 msec, respectively. There is no significant correlation of latency with age, and of latency with conduction distance to the upper trapezius. Those are measured and analyzed as a preliminary conduction study for diagnosis of neck dissection patient.
