ELECTROPHYSIOLOGIC EVALUATION OF INTERMITTENT SACRAL NERVE DYSFUNCTION IN LUMBAR SPINAL-CANAL STENOSIS

Intermittent sacral nerve dysfunction, induced by walking in lumbar sp inal canal stenosis, may cause symptoms including hyperesthesia and pa in in perineum, urinary bladder incontinence, and penile erection. How ever, it is difficult to objectively document these symptoms. Evoked e xternal urethral sphincter potentials by conus medullaris stimulation were measured both before walking and after walking in five patients w ho complained of sexual organ or urinary dysfunction during walking, a nd were compared with simultaneously induced sacral nerve symptoms. Th ese potentials were also measured during surgery. Sacral nerve symptom s were reproduced by walking 80-350 meters (average 177.5 m). These po tentials disappeared in one patient and were decreased in four patient s at the time when the claudicant symptoms disabled the patient during walking. The amplitude subsequently recovered in keeping with relief of those symptoms during rest. Monitoring of these potentials during s urgery showed an increase of amplitude shortly after the decompression procedure of the cauda equina. In conclusion, this measuring method w as valuable as an objective evaluation of intermittent sacral nerve dy sfunction in lumbar spinal canal stenosis.