Radiological investigations and intra-operative evoked potentials for the diagnosis of nerve root avulsion: evaluation of both modalities by intradural root inspection.

Fourteen patients with traumatic brachial plexus injuries underwent intradural inspection of cervical nerve roots to evaluate radiological and intra-operative electrophysiological findings concerning cervical nerve root avulsion from the spinal cord. Four neurosurgeons of our department assessed independently from each other both myelography and CT-myelography concerning intradural nerve root lesions. Each neurosurgeon assessed a total of 26 cervical nerve roots. Two investigators assessed 6/26 and 2 investigators 7/26 nerve roots falsely concerning ventral or/and dorsal root lesions compared with the findings on intradural inspection (23% and 27% false findings). There was a considerable variance concerning the assessibility and findings among the 4 neurosurgeons. Reconstructive surgery was performed after a mean interval of 6.5 months following trauma and 2 weeks following intradural inspection. After exposure of the brachial plexus and the cervical nerve roots in question via a ventral approach, 13 cervical nerve roots were stimulated electrically close to the neuroforamen and cortical evoked potentials (root-SEPs) were recorded from the contralateral postcentral region. All 5 roots with SEPs were intact (no root lesion) and all 8 roots without SEPs showed interrupted (ventral or/and dorsal) rootlets on intradural inspection. Our results demonstrate that false radiological findings concerning root lesions are possible. Intra-operative root-SEPs seem to be a useful aid for evaluation of cervical nerve root lesions. However, more electrophysiological data are necessary to ascertain, if this modality is able to replace intradural inspection in unclear radiological cases in the future.