Remarks on Spinal Cord Stimulation and the Placebo Effect

Spinal cord stimulation, which has been shown to be beneficial in multiple sclerosis as well as in sustained spinal cord injury, works through modification of specific motor mechanisms. This modification occurs through regional recruitment of spinal cord activity in posterior aspects of the spinal cord. Substantial involvement of the placebo effect can be ruled out by noting the persistence of beneficial effects observed in spinal cord injury patients and by the fact that the effects are related only to depolarization of posterior structures of the spinal cord, rather than to perception of a ''tingling'' sensation caused by spinal cord stimulation. Such a sensation can also occur when electrodes are over anterior or lateral structures of the spinal cord, when the stimulation is not effective in alleviating motor symptoms.