CONSTRUCTION OF A URINARY SPHINCTER BY MEANS OF AN ELECTRICALLY STIMULATED STRIATED-MUSCLE - EXPERIMENTAL PROCEDURE AND URODYNAMIC RESULTS ON CANINE MODEL

A canine model of urinary neosphincter using electrically stimulated a utologous striated muscle is described. The superior belly of canine s artorius was activated by a pacemaker with an intermittent low frequen cy stimulation (0.5-1 pulse per sec) during 7 weeks. Then, the muscle graft was passed around the urethra and sutured back on to itself to f orm a neosphincter. The surgical procedure was easy to perform and wit h no complication. Urethral pressure profile was performed initially ( T0), and when the muscle was in peri-urethral position, before (T1) an d during electrical stimulation (T2). The continence parameter reading s (maximal urethral closure pressure MUP, functional length FL, contin ence zone CZ, and continence area CA) increased from T0 to T1, acid fr om T1 to T2. We noted: 1) 28%, 38%, 52%, and 86% increases for the MUP , FL, CZ, and CA respectively from TO to T1, 2) 10%, 41%, 30%, and 43% increases for MUP, FL, CZ, and CA respectively from T1 to T2. Chronic low frequency stimulation could transform a skeletal fast-twitch type 2 muscle into a slow-twitch fatigue-resistant type 1 muscle. In this study, morphological changes of the stimulated muscle were noted, wher eas phenotype was unchanged. This dynamic autologous neosphincter may be a new alternative to the artificial urinary sphincter prosthesis wi th fewer complications. Further studies are ongoing to evaluate the ef ficacy of such a neosphincter as continent system for bladder substitu tion after pelvic exenteration for pelvic cancers.