potential detected at the distal end of spinal nerve. However, surgical repair is possible because proximal nerve tissue has enough length for stitching. Impact Heavy impact to the shoulder is the second common mechanism to causing injury to the brachial plexus. Depending on the severity of the impact, lesions can occur at all nerves in the brachial plexus. The location of impact also affects the severity of the injury and depending on the location the nerves of the brachial plexus may be ruptured or avulsed. When passing through between the clavicle and first rib, the brachial plexus may be crushed in the costoclavicular space. This is usually due to direct trauma to the shoulder or neck region as a result of vehicular accidents, occupational injuries or sports injuries. The brachial plexus may also be compressed by surrounding damaged structures such as bone fragments or callus from the clavicular fracture, and hematoma or pseudoaneurysm from vascular injury. Cervical rib, prominent transverse process, and congenital fibrous bands can also compress the brachial plexus and cause thoracic outlet syndrome. During the delivery of a baby, the shoulder of the baby may graze against the pelvic bone of the mother. During this process, the brachial plexus can receive damage resulting in injury. The incidence of this happening at birth is 1 in 1000. This is very low compared to the other identified brachial plexus injuries. Diagnosis The most accurate test for diagnosing a brachial plexus injury is operative exploration of the potentially injured segments from the spinal roots to end-organs. Nerves should be evaluated under an operative microscope, with or without intraoperative electrical studies (e.g. bipolar stimulation, SEPs or MEPs) to supplement. Operative evaluation of the rootlets within the spinal canal and intraforaminal portion of the spinal roots proximal to the dorsal root ganglia (e.g. via hemilaminectomy or otherwise) is difficult and rarely clinically justifiable, so in the context of an apparently in-continuity root, preoperative imaging studies are the only method of evaluating this section of nerve. The best non-invasive test for BPI is magnetic resonance imaging (MRI). MRI aids in the assessment of the injuries and is used to provide information on the portion of the plexus which cannot be operatively explored (the rootlets and roots). In addition, assessment of the cervical cord, post-traumatic changes in soft tissues and associated injuries (e.g. fractures, cuff tears, etc.) may be appreciated. Although superior to nerve