Effect of implanted epidural stimulator on lower urinary tract function in spinal-cord-injured patients

A spinal cord stimulator was implanted in the epidural space in 33 spinal-cord-injured patients for the treatment of severe extremity spasticity. We prospectively evaluated the effect of the stimulator on the lower urinary tract in these patients. Urodynamic evaluation was performed preoperatively, and in 23 patients 3 months to 1 year after implantation. Postoperative changes in the lower urinary tract function were noted in 6 patients. One patient converted from detrusor areflexia to detrusor hyperreflexia, and 1 patient converted from detrusor hyperreflexia to detrusor areflexia. Four patients demonstrated changes in the duration of detrusor contraction and external sphincter dyssynergia. In 2 of these 4 patients, the changes in the duration of detrusor contraction and external sphincter dyssynergia were related to the activation and deactivation of the stimulator. Urodynamic parameters did not change significantly following implantation in the remaining 17 patients. We conclude that epidural stimulator implanted for the treatment of spasticity may alter the lower urinary tract function. Patients with postoperative changes in the lower tract function should be evaluated with the stimulator activated and deactivated.