Factors Affecting C5 Viability and Demographic Variability in Two Brachial Plexus Centers

Background: Complete brachial plexus injuries are devastating injuries. A viable C5 spinal nerve can offer additional sources of axons and alter surgical treatment. We aimed to determine factors that portend C5 nerve root avulsion. Methods: A retrospective study of 200 consecutive patients with complete brachial plexus injuries at two international centers (Mayo Clinic in the United States and Chang Gung Memorial Hospital in Taiwan) was performed. Demographic information, concomitant injuries, mechanism, and details of the injury were determined, and kinetic energy (KE) and Injury Severity Score were calculated. C5 nerve root was evaluated by preoperative imaging, intraoperative exploration, and/or intraoperative neuromonitoring. A spinal nerve was considered viable if it was grafted during surgery. Results: Complete five-nerve root avulsions of the brachial plexus were present in 62% of US and 43% of Taiwanese patients, which was significantly different. Increasing age, the time from injury to surgery, weight, body mass index of patient, motor vehicle accident, KE, Injury Severity Score, and presence of vascular injury significantly increased the risk of C5 avulsion. Motorcycle (≤150cc) or bicycle accident decreased the risk of avulsion. Significant differences were found between demographic variables between the two institutions: age of injury, body mass index, time to surgery, vehicle type, speed of injury, KE, Injury Severity Score, and presence of vascular injury. Conclusions: The rate of complete avulsion injury was high in both centers. Although there are a number of demographic differences between the United States and Taiwan, overall the KE of the accident increased the risk of C5 avulsion.