The cervical somatosensory evoked potential (SEP) in the diagnosis of multiple sclerosis.

Abnormalities of the potential evoked by stimulation of the median nerve and recorded over the cervical spine were found in 59% of patients with multiple sclerosis (MS) this proportion increasing to 69% of those in the definite diagnosis category and to 100% in the severely disabled. Abnormalities were often found in the absence of relevant clinical signs and the method appears to be capable of revealing clinically silent plaques. In patients with a single episode of neurological disease, including retrobulbar neuritis, and at least compatible with the onset of MS, the proportion of abnormalities did not rise above 18%. Only prolonged follow-up will permit assessment of the value of this and other evoked potential techniques in the detection of the early case of the disease.