Ultrasound evaluation of the striated urethral sphincter as a predictive parameter of urinary continence after radical prostatectomy

Objectives: The purpose of this study was to evaluate preoperatively the results of transrectal ultrasound (TRUS) in the detection of morphological, vascularization status of urethral rhabdosphincter (RS) and evaluate the correlation with urinary continence after radical prostatectomy (RP). Methods: 211 patients who underwent RP were prospectively studied using TRUS scan of the RS thickness. At the end of the examination a study was performed with the use of colour-Doppler for the assessment of the RS vascularity pattern. The level of continence was graded on a 5 point scale as: 1 = complete continence, 2 = 1 pad daily, 3 = 2-3 pads daily, 4 = 4 or more pads daily, and 5 = complete incontinence. Results: It was possible to visualize the rhabdosphincter and its vascularity in all patients. Patients with normal continence (level 1 and 2) showed a sphincter-muscle thickness of 3.5 mm (± 0.4) and a hypoechoic ultrasound pattern. With respect to the other levels 3, 4 and 5 of urinary incontinence RS thickness was 2.8 mm (± 0.5), 2.1 mm (± 0.6), 1.7 (± 0.7) respectively. Incontinence after RP (≥ 3 level) was associated with urethral sphincter deficiency in the great majority of patients. Statistical significant differences were observed in the vascularity between continent and incontinent men in all measured vascularity variables (p < 0.005). Conclusions: This study suggests that RS integrity is a good predictor of urinary continence after RP and this information can be important during the preoperative phase as part of the informed consent.

Improvement of Urethral Sphincter Deficiency in Female Rats following Autologous Skeletal Muscle Myoblasts Grafting

Sphincteric deficiency is the most common cause of urinary incontinence in humans. Various treatments have lead to disappointing results due to a temporary benefit. Recent studies raised the possibility that sphincteric deficiency could be treated by implanting skeletal myoblasts. In the present study, we developed in the female rat a model of chronic sphincteric defect to assess the benefit of myoblast injection. Sphincter deficiency was induced by freezing, longitudinal sphincterotomy, and notexin injection, respectively, to obtain a reproducible and irreversible incontinence. Autologous tibialis anteriors were cultured to be injected in the best model. Functional results were evaluated by measuring the urethral pressure with an open catheter. Histology was performed in the excised urethras. Of the three techniques, only longitudinal sphincterotomy caused definitive incontinence by irreversibly destroying the striated sphincter muscle fibers: a 45% decrease of the closure pressure was observed 21 days after the sphincterotomy. At this time, we injected myoblasts at the sphincterotomy site. In the sham-injected group (n = 18), the closure pressure decrease was not significantly modified 21 days after injection. By comparison, a return to near normal value was observed after cell grafting (n = 21). These results and those obtained by others strongly suggest that the use of myoblasts could be a potential innovative therapy for urethral deficiencies leading to incontinence.