Somatosensory evoked potential testing in multiple sclerosis.

Evoked potentials can be elicited by electrical stimulation of the median nerve or other locations. Recordings can be made of the electrical signals at the peripheral nerve, plexus, spinal cord, brainstem, and hemispheric levels. When the stimulation and recording techniques are kept constant, the evoked potentials can be used to measure pathophysiological abnormalities in MS and other conditions. Evoked potentials are abnormal in most persons with MS, which helps to establish the diagnosis. These techniques also hold promise of value in clinical trials of possible MS therapies and as an aid in the epidemiological and genetic studies of MS.