Levator-urethral reflex. A new reflex with clinical significance

A preliminary study of a new reflex which I called "levator-urethral reflex" is presented. Twenty-three volunteers were studied. Two concentric needle electrodes were introduced: one in the levator ani muscle (stimulating electrode) and the other in the external urethral sphincter (recording electrode). Levator stimulation evoked external sphincter contraction in all the subjects. The anesthetized sphincter did not respond while the saline-infiltrated one responded. The mean latency of the reflex was 168 ms. The levator-urethral reflex regulates the relation between micturition and continence. Reflex external urethral sphincter contraction keeps micturition under control despite the involuntary opening of the vesical neck as a result of levator contraction. Measurement of the latency of the reflex could be an objective and accurate means of investigating micturition disorders.