Internal anal sphincter augmentation for fecal incontinence using injectable silicone biomaterial

PURPOSE: A disrupted or weak internal anal sphincter can lead to passive fe cal incontinence. This muscle is not amenable to direct surgical repair. Pr evious preliminary at tempts to restore functional continuity have included a cutaneous flap to fill an anal canal defect, and injection therapy using polytetrafluoroethylene, collagen, or autologous fat. Urologists have also used injections of collagen or silicone to enhance bladder neck function. This pilot study aimed to assess the efficacy of single or multiple injecti ons of the silicone-based product Bioplastique(TM) for the symptoms of pass ive fecal incontinence caused by an anatomically disrupted or intact but we ak internal anal sphincter. PATIENTS AND METHODS: Ten patients (6 females; median age, 64; range, 41-80 years) with passive incontinence secondary to a weak (n = 6) or disrupted (n = 4) internal anal sphincter a ere injected either circumferentially or at a single site, respectively. Patients were a ssessed before and six weeks after treatment by clinical assessment, two-we ek bowel diary card, anorectal physiologic testing, and endoanal ultrasound . Patients failing to show improvement after the first injection were offer ed a second injection six weeks after the first injection. Clinical assessm ent was further repeated at six months, and five patients had a further ult rasound examination. RESULTS: At six weeks, six of ten patients showed eith er marked improvement (n = 3) or complete cessation of leakage (n = 3). A f urther patient was greatly improved after a second injection. Three patient s were not improved. At six months, two of the seven patients had maintaine d marked improvement, and one patient had maintained minor improvement; all of these three patients had circumferential multiple injections. Maximum r esting and squeeze anal pressures did not differ significantly between befo re vs, six weeks after vs. six months after injection. At six weeks endoana l ultrasound (n = 9) confirmed the presence and correct position of the sil icone in all but one patient who had experienced obvious external leakage o f the product. At six months the silicone remained in the correct position in the five endosonographically assessed patients. Five of the initial pati ents experienced pain or minor ulceration at the injection site. CONCLUSION S: Although clinically effective immediately after injection, the benefit o f an injectable biomaterial was maintained in only a minority of patients. This occurred despite the continued presence of material in the correct ana tomical site. Patients With diffuse weakness treated by circumferential inj ection seemed to be the most responsive, but further studies are required t o clarify this.