Objectives: Management of traumatic lesions of the brachial plexus mainly depends on whether the injury is pre- (nerve root avulsion) or postganglionic (trunks and cords). The aim of this study was to assess the diagnostic and prognostic value of MRI in such lesions, and to determine any correlations among radiological, clinical and electroneuromyographical (EMG) data from both the initial and follow-up studies.
Material and methods: Nine patients with acute traumatic lesions of the brachial plexus were investigated by MRI and EMG. Five further patients served as controls. The MRI protocol included fast spin-echo (FSE) T2-weighted and STIR sequencing. These scans were independently interpreted by two senior radiologists. Their findings were then validated during consensus meetings of surgeons, radiologists and neurologists to identify the exact localization and mechanism of each lesion, and to determine the advantages and drawbacks of each technique.
Results: Among the nine patients, MRI scans were judged as normal in three whereas EMG showed distal lesions in two of them. In a further three patients, STIR MRI sequences demonstrated high signal intensities from the trunks and cords of C5 to T1. Among these three patients, MRI at three months showed persistence of these signal anomalies in one patient, and partial regression in the two others. In the remaining three patients, three-dimensional T2-weighted sequences showed nerve root avulsion, consistent with the initial EMG findings.
Conclusion: MRI is the best technique to demonstrate nerve root avulsion. However, unlike EMG, MRI does not allow visualization of distal lesions of the brachial plexus. Differentiation between edema (reversible) and demyelination (irreversible) of trunk and cord lesions remains difficult, and requires EMG or late MRI.