Electrophysiological responses and stimulus parameters associated with spinal cord stimulation.

Cervical somatosensory-evoked potentials and brainstem-click-evoked potentials were recorded from 10 patients with multiple sclerosis before and after a trial of spinal cord stimulation. An improvement in amplitude of the cervical somatosensory-evoked potential was seen in 7 out of 8 patients, while 3 out of 10 showed a decrease in latency of the brainstem-evoked potential. Stimulus currents were measured during spinal cord stimulation, and those patients requiring high currents to evoke a sensation did not derive clinical benefit from spinal cord stimulation.