In the last 2 decades great progress has been made in the care of patients with neurogenic bladders. The development of antibacterial therapy for urinary tract infections, the recommendation of intermittent catheterisation in place of continual catheter drainage, and the judicial use of operative procedures to relieve obstruction or to divert the urine, have all reduced the urologic morbidity and mortality associated with this problem. There are still some patients, however, who continue to have recurrent urinary tract infections, who do not develop a satisfactory reflex bladder, and who do not respond satisfactorily to intermittent catheterisation.The initial report of stimulation of the spinal cord and pelvic nerves occurred over 100 years ago (Budge, 1864). In the intervening years a stimulus has been given to the pudendal, hypogastric and pelvic nerves as well as the bladder, in animal laboratories. Clinical experimentation was initiated by Dees in 1940 using an intrarectal probe, and intravesical catheter-electrodes (Katona, 1958) and electrodes implanted into the detrusor muscle have also been used. The failure rate in these early studies was high and prompted our interest in a more satisfactory means of achieving complete micturition.
MaterialsOur initial laboratory efforts (Friedman, Nashold and Senechal, 1972) involved acute and chronic experiments on cats and dogs. Surface stimulation of the lumbar and sacral spinal cord elicited excellent bladder pressures, but without micturition. Highest bladder pressures were obtained at the S2 level. Stimulation above Sl induced activation of skeletal muscle with contraction of the perineal musculature and tonic-clonic movement in the lower extremities.Use of a depth electrode induced similar bladder pressures with voiding. Descending visceral motor pathways for the bladder lie in the medial portion of the lateral columns and it was felt that positioning the electrodes within the central grey matter induced their activation. Subsequent autopsy examination of adult human spinal cords yielded an average depth for the intermediolateral grey column in the sacral cord of 2.5 mm. The chronic depth electrodes now used consist of 2 platinum-iridium wires 2.5 mm in length and 2.5 mm apart, mounted on a Silastic clip.The electric parameters found most helpful include a biphasic square wave at 15-20 cycles per second. The stimulus is applied for 20-30 seconds using lo-15 volts.Clinical experimentation using this stimulator was begun in 1970 and has been used in 10 patients Grimes, Nashold and Currie, 1973). The procedure was approved by the medical committee on human experimentation and the experimental nature was discussed with the patient and his family.
ProceduresCareful patient selection and evaluation should be conducted before consideration of implantation of a spinal cord stimulator. In this initial patient group, only paraplegics have been con-