A HETEROTOPIC AUTOINNERVATED URINARY NEOSPHINCTER

Twenty-six female adult New Zealand white rabbits underwent surgical d enervation of a gracilis muscle to study the possibility of developing an autologous neosphincter innervated by the pudendal nerve. The stud y was conducted in 2 phases. In both Phase I and Phase II, the study g roup had the motor nerve to the gracilis, a branch of the obturator ne rve and the pudendal nerve coapted in the perineum. The control group was left denervated. In Phase I, all muscle flaps were wrapped around the urogenital sinus. In Phase II, the muscle flaps were returned to t heir anatomic location. With balbocavernosus reflex testing, 89% of th e reinnervated group and 60% of the denervated group from Phase I and 86% of the reinnervated group and none of the denervated group from Ph ase II had a contractile response in the muscle flap. In Phase II, his tologic examination of the gracilis muscle was suggestive of an early change in muscle myofiber physiology from fast twitch to slow twitch i n the reinnervated group only. In the rabbit, a transplanted vasculari zed muscle flap, cross-innervated by the pudendal nerve has a reproduc ible response to bulbocavernosus reflex testing. This suggests that a transplanted muscle might be able to assume some of the characteristic s of the voluntary urinary sphincter. The rabbit is a useful model in which to investigate the potential of the heterotopic neosphincter.