The role of motor-evoked potentials in the management of cervical spondylotic myelopathy.

Abstract

Cervical spondylotic myelopathy (CSM) is a common disorder, but its management and the role of surgery are still a matter of controversy. The assessment of surgical outcome is complicated by the lack of reliable and objective methods to assess the severity of the myelopathy and its evolution. Motor-evoked potentials (MEPs) are a useful and reliable tool to measure noninvasively the involvement of the corticospinal tract in patients with CSM. Recent evidence suggests that MEPs could also have a role in monitoring the effect of surgical therapy. The aim of the present study is to use MEPs for the functional assessment of spinal cord before and after surgery and to correlate changes in MEPs with clinical findings. This is a retrospective cohort study. Thirty-eight patients affected by CSM who underwent surgical intervention. We used the 18-point modified Japanese Orthopedic Association (mJOA) score for clinical evaluation and the central motor conduction time (CMCT) for the study of MEPs. All patients were evaluated both clinically and neurophysiologically before (7-15 days) and after (6-12 months) surgery. MEPs were recorded from the biceps, abductor digiti minimi, and tibialis anterior muscles bilaterally. After surgery, the 18-point mJOA score increased significantly from 10.1 to 15.1, and the value of CMCT for tibialis anterior muscles showed a slight but significant reduction, more evident in patients with mild to moderate symptoms. Early surgical intervention for CSM could produce a beneficial effect on spinal cord functionality that can be detected by MEPs.