ABSTRACT

Significant changes in function of perineal innervation have been observed in 27 patients treated with sacral nerve neuromodulation. Using electrodiagnostic techniques, performed with an Interstim implantable pulse generator switched on and off, we observed that sacral nerve neuromodulation increases the amplitude of voluntary contraction of the urethral sphincter, decreases the duration of motor unit potentials at rest in both sphincters and reduces latencies of pudendal nerve terminal motor bilaterally. These results suggest a greater recruitment of pelvic muscular fibers and a better synchronization of the fibers firing. Sacral nerve neuromodulation probably increases the motor conduction velocity of pudendal nerves and so suppresses integration between peripheral innervation and spinal cord.