Spinal cord stimulation: a quarter century of development and investigation. A review of its development and effectiveness in 1,336 cases.

The past two and a half decades have seen the development of a spinal cord stimulator from the early 2-electrode fixed system to the present multielectrode computerized systems. During these 25 years, spinal cord stimulation has been studied in the treatment of motor disorders. The effectiveness was studied in 1,336 cases, including cerebral palsy (456), dystonia (173), torticollis (90), multiple sclerosis (130), spinocerebellar degeneration (71), spinal cord injury (303) and posttraumatic brain injury (113). It has become increasingly evident that the maximum therapeutic effect is achieved by virtue of the applied field variables of the spinal cord level stimulated, the field configuration, its polarity, and the frequency of the stimulation. These observations have led to investigational corollaries of the therapeutic specificity of the applied field, the neurophysiologic mechanisms of these fields and the underlying abnormal neurophysiologic substrate, which may indeed be secondary to abnormalities in the nerve impulse itself.