Role of neurosacral modulation for the treatment of persistent post prostatectomy urinary incontinence after transobturatory sling implant. Our experience
Urinary incontinence following radical prostatectomy has yet a significant incidence, varying from 4% to 8% in modern series, and impairs deeply quality of life . The number of radical prostatectomies performed in 2010 in US was about 138000 (source Center for Disease Control and Prevention, http://www.cdc.gov/nchs/fastats/prostate.htm) and therefore the number of patients involved is significant as well and can be estimated in 5500 to 11.000 de novo incontinent cases per year. Incontinence is mainly a consequence of external sphincter weakness. However a concomitant urge component can be present in at least a fifth of incontinent cases [2,3] and best assessed only after an appropriate “restitutio ad integrum” of the sphincter function. Hence, the partial effect achieved after surgery for post prostatectomy incontinence could be due to a failure and/or to the presence of minor or latent functional bladder dysfunction, which becomes dominant after the surgical correction of the sphincter defect. After urodynamic evaluation assessing the presence of the bladder dysfunction, sacral neuromodulation may be offered in order to improve continence and quality of life. Our report is intended to assess feasibility of sacral neuromodulation for the treatment of the urge component of incontinence in this specific clinical scenario.
Materials and Methods
Our report is prospective case series without a control group or randomization.Internal review board approved our data analysis. The study was conducted according to the Helsinki Declaration.
From January 2010 to December 2011, 77 patients referred to our center for post radical prostatectomy incontinence. Cases characterized by partial intrinsic sphincter deficiency (defined as functional length less than 2 cm, retrograde leak point pressure test < 40 cm H2O, maximal urethral closure pressure < 45 cm H2O) and mild incontinence (24h pad test lower and upper limits respectively 20 and 500 mL, computed as 3 days mean) underwent transobturatoy tensive perineal tape placement . Twenty seven patients declared a partial or no improvement and were submitted again to urodynamic evaluation. Twenty-five cases with a reduced bladder compliance (<10 mL/cm H2O) or reporting a partial improvement after a trial with anticholinergic drugs were candidates to sacral neuromodulation. Twenty-two were implanted with sacral neuromodulator (InterStim – Medtronic) . Before implantation patients signed a detailed informed consent. Patients were followed up with interview, physical examination, ICIQ-SF questionnaires and pad test before and post implantation, at 3 months and then yearly. The interview included a detailed continence assessment: number of pads used, number of incontinence episodes, number of days affected by incontinence. Complete responders were dry cases, not necessitating anymore of pads. Partial responders were defined as cases that more than halved the number of pads used or reported a reduction of at least of 50% of incontinence episodes or days affected by incontinence. ICIQ-SF and pad test findings pre and post implant were subjected to a Student’s T –test for paired samples for analysis of statistical significance.The object of the analysis were the 2-year findings.. The test was two tailed for ICIQ-SF assessment and one tailed for the pad test. Significance level was 0.05.
Two patients died within 2 years after the implant, one for disease and one for unrelated causes whereas 18 had at least 2 year follow up and were object of the report. Indications to implantation were bladder compliance < 10 cm H2O and improvement of continence during the anticholinergic drugs trial in 4 cases (group 1), bladder compliance < 10 cm H2O without improvement with drugs in 8 cases (group 2), bladder compliance >10 cm H2O and improvement with drugs in 6 cases (group 3). Median age at prostatectomy was 72 (range 44 – 78), median number of years from prostatectomy to implant was 2 years (range 2 – 14). Two years after the implant, 4(22%) patients were completely continent (no pad), 4(22%) quasi-continent (1 pad), 5(28%) improved of at least 50% (halved the number of pads) and five improved of at less than 50% or did not at all respect to pre implant assessment. Concerning the number of incontinence episodes, 11 (61%) had a reduction greater than 50% whereas the number of days affected by incontinence reduced more than 50% in 10 (56%) cases. Overall 13/18 patients (72%) had a complete or partial response to the treatment and, most important, 10/18 (55%) declared to be satisfied and happy to have decided to be treated. The pads’ number was reduced significantly from 4.4 ± 2.2 to 1.9 ± 1.6 (p<0.001). The ICIQ-SF score decreased significantly from 16.3 ± 3 a 10.9 ± 4.5 (p<0.001). Data are summarized in table 1. Stratifying according to indication of implantation, group 1 patients were more likely to respond than group 2 and 3 patients, with a rate of respectively 4/4, 5/8, 3/6. Interestingly all the complete responders belonged to group 1.
Patients submitted to radical prostatectomy, irrespective of the technical approach, open, laparoscopic, robotic, may develop permanent urinary incontinence  with similar rates
, ranging from 4% to 8%. Considering the number of prostatectomy performed every year, the number of patients affected by incontinence is significant. Data suggest that most are mainly stress incontinence cases and only a minority, about 4%, is linked solely to overactive bladder . However concomitant impaired compliance and detrusor hypocontractility in stress incontinent cases have a significant incidence and are reported in up to 40% and 60% of patients respectively [1, 7, 8, 9]. Particularly urodynamic studies performed after radical prostatectomy in incontinent patients, show that detrusor overactivity can be found in at least one fifth cases [2, 3, 10] and coexist with sphincter weakness. The gold standard for the treatment of stress post prostatectomy incontinence is the artificial urinary sphincter which is successful in about 80% of cases , however, in selected cases with mild incontinence, slings have comparable results  and less complications [13,14]. Our cohort consisted of properly selected cases. Anastomotic stricture was excluded by office cystoscopy, degree of incontinence was mild and urodynamic findings identified intrinsic sphincter deficiency. However only an half recovered from incontinence. Our study focuses on cases not responding, totally or partially, to sling placement. Given the significant incidence of bladder impaired compliance concomitant to stress incontinence, every patient was resubmitted to urodinamic study. Sacral neuromodulation was offered to cases with a bladder compliance <10 mL/cm H2O or clinical improvement of continence after a trial with anticholinergic drugs. Sacral neuromodulation was preferred to tibial nerve stimulation simply because it does not imply repeated weekly office visits. Patients were prospectively followed up. In all, 18 patients had a follow up lasting at least 2 years and were object of our study. Sacral neuromodulation may improve continence by a wide range of mechanisms, related to the stimulation of sensitive and motor neural fibers of the ventral ramus localized at the S3 level, as eloquently described in a paper from Chancellor and Chartier-Kastler . Return to continence in about half of patients shows effectiveness of sacral neuromodulation as treatment of urge incontinence also in this clinical setting. Moreover, satisfaction rate, expressed by a direct and precise question to the patient was significantly high considering the general dissatisfaction underlying post prostatectomy continence and a “failed” sling implant. The impression obtained by interviewing the patients is substantiated by an objective and statistically significant improvement in ICIQ-SF score and number of pads used. We reported ours results over a period of 2 years thus suggesting the achievements are likely to remain definitive. Interestingly, even if not statistically significant, the patients who benefit most from the implant were those with a bladder compliance < 10 cmH2O and who experienced a continence improvement after a trial with anticholinergic drugs. Indeed failures should have probably an additional incontinence component beyond impaired bladder compliance linked to the prostatectomy technique like a too short urethral stump or urethral fibrosis .
In this series of selected patients, the residual urinary incontinence was treated effectively with sacral neuromodulation when the urodynamic evaluation, performed after the implant of the sling perineal bulb, showed a reduction in bladder compliance. The 2-year follow up is not yet enough to consider definitively stable the results achieved even if it will likely remain unchanged. Most important the procedure is safe, mini invasive and performed in local anesthesia. The procedure is feasible but further studies are needed to validate the technique and its results. By the way our report should encourage centers specialized in male incontinence treatment to perform dedicated clinical trials focusing on the population who is most likely to respond, namely cases with a bladder compliance < 10 cmH2O and reporting an incontinence improvement after a trial with anticholinergic drugs.
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