Predictive criteria for failed sphincterotomy in spinal cord injury patients.

Nine patients with chronic high spinal cord injury who failed sphincterotomy secondary to detrusor hypocontractility underwent neurourological evaluation. Testing revealed an abnormality involving the sensory limb of the somatic sacral reflex arc (abnormal R wave) or at the level of the spinal interneuron pool (abnormal or absent S wave). This study strongly suggests that the sensory input from the bladder to the spinal cord, together with alteration in the sensory motor integration that occurs at the level of the interneuron pool, is important in influencing the characteristics of the detrusor contraction following high spinal cord injury. Predictive criteria for failed sphincterotomy are a slow increase to maximum intravesical pressure before voiding and abnormal lumbosacral sensory evoked potentials.