[Nerve injuries and traumatic lesions of the brachial plexus : Imaging diagnostics and therapeutic options].

CLINICAL/METHODICAL ISSUE: Traumatic lesions of peripheral nerves and the brachial plexus are feared complications because they frequently result in severe functional impairment. The prognosis is greatly dependent on the correct early diagnosis and the right choice of treatment regimen. It is important to distinguish between open and closed injuries. STANDARD RADIOLOGICAL
METHODS: Initial imaging must critically evaluate or prove nerve continuity and is commonly achieved by high-resolution ultrasonography. During the further course, reactive soft tissue alterations, such as constrictive scarring or neuroma formation can be detected. In the case of deep nerve and plexus injuries this can be excellently achieved by dedicated magnetic resonance neurography (MRN) sequences. METHODICAL INNOVATIONS: The signal yield from brachial plexus imaging can be critically enhanced by the use of dedicated surface coil arrays. Furthermore, diffusion tensor imaging (DTI) may enable the regeneration potential of a nerve lesion to be recognized in the future. PERFORMANCE: Multiple reports have shown that neurosonography enables a precise evaluation of peripheral nerve structures (up to 90% sensitivity and 95% specificity in nerve transection) and that the method can critically impact on therapeutic decision-making in 60%. Currently, there are only few quantitative data on the exact performance of MRN in traumatic nerve lesions; however, individual reports indicate a high level of agreement with intraoperative findings. PRACTICAL RECOMMENDATIONS: In the initial work-up, especially in the case of peripheral, superficial and lesser nerve injuries, neurosonography is the preferred imaging approach to evaluate nerve integrity and the extent of nerve lesions. In the case of extensive nerve injury of proximal nerves and structures of the plexus as well as in the case of suspected root avulsion MRN is the method of choice.