Spinal epidural corticomotor evoked potentials as a predictor of outcome from ischaemic myelopathy

Corticomotor evoked potentials have been suggested to accurately reflect neurological function, particularly with regard to the integrity of the spinal cord. However, the utility of these potentials to evaluate graded, chronic injury has received little attention. Using a rabbit model of ischaemic spinal cord injury we recorded corticomotor evoked potentials before, during, immediately after, and three days after producing an ischaemic spinal cord injury by inflating an intraaortic balloon. The animals sustained a stable mild, moderate, or severe neurological deficit. All ischaemic injured animals demonstrated near loss of the corticomotor evoked potential after the timed balloon occlusion period. Mildly injured animals did not demonstrate significant differences in corticomotor evoked potentials at reperfusion of three days post injury, when compared to controls. However, moderate and severely injured animals revealed significant reduction in late latency component amplitudes by > 50% and > 90%, respectively, when compared to controls. Changes in corticomotor evoked potential features are associated with altered neurological function after graded spinal cord injury.