Correlation between transcranial motor and somatosensory-evoked potential findings in cervical myelopathy or radiculopathy during cervical spine surgery.

BACKGROUND: The correlation between electrophysiological recordings, MR images, and physical findings in cervical stenosis and cervical myelopathy are still open to debate. The goal of this study was to determine sensitivity of motor-evoked potential (MEP) and somatosensory-evoked potential (SSEP) in detecting cervical myelopathy and its correlates with the MRI findings in patients undergoing cervical spine surgeries.

METHOD: Transcranial motor-evoked potentials (TcMEPs) and SSEPs were performed intraoperatively in 100 patients. The 'baseline' recordings of TcMEPs and SSEPs were correlated with patient's physical findings as well as the MR images.

RESULTS: Posterior tibial and median nerves' scalp SSEP latencies were increased in myelopathic patients compared to the radiculopathy group. MEPs recorded from distal muscles such as abductor pollicis brevis and adductor hallucis (AH) muscles were more likely to be absent in myelopathic patients compared with the patients with only radiculopathy. The myelopathic patients were more likely to have no response (NR) for the lower extremity SSEP test compared with radiculopathy patients.

CONCLUSION: MEP shows more sensitivity toward detecting myelopathy which is correlated well with abnormal MR images.