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 hemilamiinectomy 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 conduction studies, ultrasound and other tests, conventional MRI has a poor specificity (72%) meaning that the false-positive rate is high and surgeons cant rely upon the test to guide treatment. Consequently, the future of peripheral nerve MR imaging (including imaging brachial plexus injuries) is likely to be based on diffusion-weighted imaging, such as diffusion tensor techniques, which are of significant potential clinical utility and can enable the production of easily interpreted 3D reconstructions of the spinal cord and brachial plexus such as this. Several weeks/months after BPI, EMG examination can provide additional information about whether the muscle is denervated. These examinations are painful, highly user-dependent and lack normal values so cannot be relied upon. Classification
The severity of brachial plexus injury is determined by the type of nerve damage. There are several different classification systems for grading the severity of nerve and brachial plexus injuries. Most systems attempt to correlate the degree of injury with symptoms, pathology and prognosis. Seddons classification, devised in 1943, continues to be used, and is based on three main types of nerve fiber injury, and whether there is continuity of the nerve. Neurapraxia: The mildest form of nerve injury. It involves an interruption of the nerve conduction without loss of continuity of the axon. Recovery takes place without wallerian degeneration.