Mechanisms of Injury

The leading cause of adult brachial plexus injuries is trauma resulting from a closed traction injury secondary to a high-velocity motor vehicle accident. Ninety percent of patients suffer supraclavicular lesions. A widened shoulder-neck angle at the time of injury with an adducted shoulder predisposes upper trunk injury, while shoulder abduction predisposes lower trunk injury. Penetrating open injuries, such as gunshot wounds and lacerations, are less common and usually result in infraclavicular injury with concomitant vascular injury. Glenohumeral dislocations and sports-related brachial plexus lesions also represent other causes of closed traction injuries. Nontraumatic brachial plexus injuries include iatrogenic injuries related to patient positioning and regional anesthetics, primary and metastatic brachial plexus tumors, and neuralgic amyotrophy.