[Cervical spondylotic myelopathy: motor and somatosensory evoked potentials, clinical and radiological correlation]

Somatosensory and motor evoked potentials (EPs) have been recorded in 38 patients with cervical spondylosis, documented by MRI. All were symptomatic, 23 presented with myelopathy. Somatosensory evoked potentials were abnormal in 66p.cent as well as motor evoked potentials. The N13 potential, generated by the posterior dorsal horn of the cervical spinal cord, was abnormal in 63p.cent of patients and was the only disorder detected in 12p.cent. Together, somatosensory and motor evoked potentials were abnormal in 82p.cent of patients. There was no correlation between EPs findings and radiological data. Similary, MRI and clinical data were agreeing in only 50p.cent of patients. When a spondylotic myelopathy is suspected, SEPs proved more sensitive to detect somatosensory dysfunctionning than clinical testing and radiological data were discordant with clinical status in 50p.cent of cases. In order to obtain a high sensitivity, both somatosensory and motor evoked potentials should be recorded on all limbs with a special attention to segmental cervical and cervico-medullary responses. EPs data help to identify patients with cervical cord dysfunction and thus contribute to the therapeutic decision for surgery.