Sacral neuromodulation has become a standardized treatment option for patients with no neurogenic bladder dysfunction as overactive bladder and urinary retention, without response to conservative medical management. In spite of its mechanism of action is not yet well established, an improvement of the symptomatology for these conditions has been demonstrated in several studies. Its action seems to correspond to the stimulation of peripheral afferent somatic nerves through C fibers. (1)
Furthermore, its performance does not seem to be limited to changes in the peripheral nervous system, since studies using functional magnetic resonance imaging have shown changes in brain activity in stem brain and limbic system (2). Based on this, sacral neuromodulation has demonstrated similar efficacy in the neurogenic and non-neurogenic population in terms of success, clinical outcomes, urodynamic findings, quality of life, safety and benefit in the indicated patients. (3) Currently, in our contry, there is no study validating the success of this treatment in our population, even though there is a significant number of patients with voiding dysfunction, painful bladder, overactive bladder and fecal incontinence.
This investigation attempts, precisely, to find new horizons in the use of sacral neuromodulation for the treatment of various conditions involving voiding dysfunction.

Our main outcome is to evaluate the impact on the symptomatology and satisfaction of patients with neurogenic and non-neurogenic voiding dysfunction, treated with sacral neuromodulation in our city from 2013 to 2015. Our specific outcomes were to measure the presence of pre surgical and post-surgical symptoms, evaluate the improvement in the symptoms of the patients, identify the operative complications and compare the improvement of symptomatology for each neuromodulation indications.

During 2013 and 2015 in our city, an observational, analytical and retrospective study was carried out for patients who underwent sacral neuromodulation surgery performed by the same urologist with extensive experience in the technique in eight different institutions.

 A review of electronic medical records of 60 patients on a database which registered variables both before and after procedure of patients with neurogenic lower urinary tract dysfunction (16 patients), overactive bladder (28 patients), urinary retention (9 patients), pelvic pain (painful bladder syndrome in 3 patients) and fecal incontinence (4 patients).

The clinical variables analyzed were: gender, age; sacral neuromodulation indications mentioned above, whether having a spinal cord trauma or not; medical history of hypertension or diabetes mellitus; history of chronic smoking; need for intermittent catheterization; presence of urinary incontinence, fecal incontinence or chronic pelvic pain; laterality of electrode implant, presence of complications, time of follow-up and the need for re-intervention and its cause. Additionally, in order to determine patient satisfaction with the procedure, the patients were asked for the possibility of recommending this device to someone else who presented a similar indicated condition, if they were willing to undergo, in a hypothetical case, to a new implantation of the device if needed, and thus define a total percentage of satisfaction with the treatment. 
All data were tabulated using Microsoft Excel and the values were analyzed using the SPSS 21 edition program.
Chi-square test was used for the analysis of the variables regarding the indication of the neuromodulator, such as the presence of neurogenic disorder, intermittent preoperative catheterization, presence or absence of pre-surgical urge incontinence, nocturia, frequency and amount of urine leakage in urge incontinence using Sandvik index, fecal incontinence, pelvic pain, complications with implantation, to undergo to procedure again, referral to someone else for sacral neuromodulation, improvement of symptoms over 50% and satisfaction with the treatment. 

Test variables of gender, the presence of neurogenic disorder, the history of spinal trauma, hypertension, diabetes and smoking, the need for intermittent preoperative catheterization, incontinence, nocturia, urinary frequency and amount of leakage of urine using Sandvik score, fecal incontinence, pelvic pain according to the improvement over 50% of the symptoms and quality of life were also analyzed using chi-square 

Pre and postoperative symptoms were evaluated for urinary and fecal incontinence in order to demonstrate a benefit of this therapy in these groups of patients.

Additionally, the McNemar test was used in this group of patients to determine the difference between fecal incontinence before and after surgery.

The implantation of sacral neuromodulator was carried out in 60 patients, of which 43 (71.7%) were female and 17 (28.3%) male. The mean age was 51.53 years of age with an interval of 12 to 86 years. The average follow-up was 20.65 months. In total, five indicators were used to perform the procedure from which the most frequent were overactive bladder corresponding to 28 patients (46.6%); neurogenic lower urinary tract dysfunctions in 16 patients (26.7%); urinary retention corresponding to 9 patients (15%); fecal incontinence in 4 patients (6.7%) and painful bladder syndrome (5%). 8.3% of the patients presented with spinal cord trauma, including 5 patients with incomplete spinal cord injury.

Preoperative intermittent catheterization was evidenced in 36.7% of the patients, 18% in neurogenic patients and in the same percentage in non-neurogenic patients. Urgency urinary incontinence was documented about 50% (30 patients); postoperative urinary incontinence was observed in 22 patients (36.6%); 13 patients (59%) described an improvement of 50% or more in their leakage and 8 patients obtained a complete improvement of urinary incontinence in this study. Fecal incontinence was evident in 10 patients with an improvement of 40% with sacral neuromodulation. Finally, chronic pelvic pain was presented in 7 patients with an improvement of 85%. 

Two of the three complications were due to device-related failures (Clavien-Dindo IIIb). No complications due to infection were found (Clavien-Dindo II). Re-intervention was necessary in 10 patients. Mechanical failure (mostly battery change) was evidenced in 10% of the total population.

Patients demonstrated improvement in pelvic pain, less requirement of clean intermittent catheterization and less urinary and fecal incontinence. Nevertheless, patients with a neurogenic condition showed a better success rate (83%) with final implantation. The 91% of patients would recommend the procedure and 81% would use it again as a therapy. Concerning our main outcome, symptomatic improvement and satisfaction were observed in 83.34% of the patients, demonstrating an improvement over a 50% of the symptoms and allowing patients to perform tasks in which were limited previous to sacral neuromodulator implantation. An additional important fact is that 87% of patients with neurogenic bladder presented symptomatic improvement and satisfaction. Complications were presented in 5% of patients and mechanical dysfunction of neuromodulator was the most commonly observed.

Sacral neuromodulation becomes an effective therapy, providing symptomatic improvement in patients with fecal incontinence, overactive bladder, chronic pelvic pain and neurogenic lower urinary tract dysfunction. Additional studies are needed to classify better selection criteria for each indication.

Sanford MT, Suskind AM. Neuromodulation in neurogenic bladder. Transl Androl Urol. February 2016;5(1):117-26.
Dasgupta R, Critchley HD, Dolan RJ, Fowler CJ. Changes in brain activity following sacral neuromodulation for urinary retention. J Urol. December 2005;174(6):2268-72.
Kessler TM, La Framboise D, Trelle S, Fowler CJ, Kiss G, Pannek J, et al. Sacral neuromodulation for neurogenic lower urinary tract dysfunction: systematic review and meta-analysis. Eur Urol. December 2010;58(6):865-74.