Concordance and discrepancy between electrodiagnosis and magnetic resonance imaging in cervical root avulsion injuries.

To clarify the relationships between electromyography (EMG) and magnetic resonance imaging (MRI), we compared findings in 37 selected patients who presented with cervical root avulsion injuries. Nerve root repair with C4-T1 hemilaminectomy was subsequently performed on 19 patients. The agreement between the two evaluative modalities with complete or incomplete lesions of ventral root and pre- or postganglionic lesions of dorsal root was measured for each root level. Both with ventral and dorsal root evaluation, C6, C7, and C8 yielded high agreement values, ranging from 86% to 94%. C5 manifested the lowest agreement values: 54% on ventral root assessment. Additionally, EMG, in comparison with MRI, revealed a higher quantity of implicated injured components. MRI, in turn, detected more lesion components than surgical exploration alone achieved. The capability of EMG to recognize axonotmesis leads to the discrepant findings between the two modalities. The visualization of mild neurotmesis by MRI, which cannot be achieved by surgical inspection, results in divergent findings between the two modalities. Both EMG and the MRI play crucial roles in preoperative assessment, and they may complement each other.