These patients are routinely checked by X-rays of the cervical spine, shoulder, humerus and chest. An increased incidence of skeletal injury is observed in blunt trauma with concomitant stretch injury of the brachial plexus. Fracture of transverse process of cervical vertebra indicates injury close to the cord level and may be associated with root injury. Fracture of first rib and clavicle may be associated with brachial plexus and subclavian vessel injury. Chest radiograph with an elevated dome of diaphragm may indicate phrenic nerve injury. In addition fracture of ribs may caution the surgeon against the use of intercostal nerves in neurotization. CT myelogram is a very sensitive imaging technique to define the root avulsion. A typical root avulsion is seen as pseudomeningocoele on CT myelogram following healing of dural sheath surrounding the root. Therefore myelographic study should be performed 3 to 4 weeks after the injury. However due to the invasive nature of CT myelography and its inability to demonstrate the lesions beyond neural foramina it is gradually being replaced by Magnetic Resonance Imaging (MRI).2 The use of MRI has gained popularity as an imaging tool in brachial plexus injury.3 It is non-invasive and provides details of brachial plexus anatomy. MR myelography (MRM) is a T2 weighted sequence that enhances the contrast between the spinal roots and cerebro spinal fluid.4 It therefore achieves myelogram like images. Few studies indicate MRM as good as CT myelogram in localizing root avulsions. MR neurography is a new technique which can localize the site of injury, any disruption in nerve continuity and neuroma formation The most common technique of MR imaging uses T2 weighted fat suppressed images and T1 weighted images to provide an anatomical localization. However these techniques fail to produce three dimensional images. Vascular structures like veins adjacent to the nerve are difficult to differentiate because of similar signal intensity. Three dimensional diffusion weighted MR sequence provides a contrast between nerves and surrounding structures and brachial plexus anatomy is more clearly defined. Further refinements in 3T MR neurography with three dimensional imaging has further helped clinicians to detect postganglionic brachial plexus lesions.
The electrodiagnostic studies (EDS) help in clinical diagnosis and provide useful information about peripheral nerves and muscles innervated by them. The EDS can diagnose re-innervation before the clinical recovery is evident and can be used as a follow up tool following surgery. EDS essentially record the action potential in the nerves and electrical activities in the muscle. Hence nerve functions both sensory and motor can be assessed by nerve conduction studies (NCS) and muscle electrical activity can be assessed by electromyography (EMG). In closed brachial plexus injuries EDS should be performed 3 to 4 weeks after the injury when Wallerian degeneration has taken place.