[Level diagnosis of cervical myelopathy using evoked spinal cord action potentials--clinical and experimental...

The ESCAPs (evoked spinal cord action potentials) due to both median nerve and spinal cord stimulation were recorded from the interlaminal yellow ligaments posteriorly or intervertebral discs anteriorly on 12 neurologically normal adults, 50 patients with cervical myelopathy and 10 cats in order to determine the main lesion in the cervical cord electrophysiologically. The abnormal ESCAPs obtained from 50 patients with cervical myelopathy were classified into three groups as follows: Grade 1; slightly abnormal, Grade 2; moderately abnormal and Grade 3; severely abnormal which had the positive wave. In general, there was a tendency that the patients graded higher had lower evaluating score of the Japanese Orthopaedic Association. The spinal level on which the highest grade of ESCAPs was recorded generally corresponded to the level which was clearly diagnosed as the main lesion by neurological and radiological examinations, such as the case of single level disc hernia. Therefore, it has become possible to diagnose the main lesion of cervical myelopathy by recording ESCAPs.