Overactive bladder (OAB) and non-obstructive chronic urinary retention (NOCUR) are two common conditions that seriously impact patients’ quality of life. Sacral neuromodulation (SNM) is an established treatment modality for these two very different manifestations of lower urinary tract dysfunction, when conservative treatment fails. In the population with OAB, several studies show a reduction in frequency and urge urinary incontinence (UUI) in more than 50% of patients. In the NOCUR population, some series show even better results, with up to 70% of patients with a positive response. 
SNM is implanted as a staged procedure. In the first stage an electrode is placed via a sacral foramen, usually S2 or S3, and attached to an external test stimulator. Test stimulation is considered successful when there is a reduction in one or more micturition symptoms >50%. Following a successful test stimulation, patients are candidates for the second stage of the procedure, where the electrode is connected to an implanted pulse generator. 
Despite being an approved treatment/as a treatment line, recent data about SNM outcomes and patient satisfaction in the current practice is scarce.
The aim of this study is to evaluate the effectiveness, satisfaction, and safety of SNM in patients with refractory lower urinary tract dysfunction in our institution.

A retrospective analysis of patients that received SNM from October 2013 to December 2021 in our institution was conducted. All the patients were submitted to SNM therapy for OAB or NOCUR. Patient demographics, associated comorbidities, symptoms, previous treatments and complications were reviewed. The number of pads and clean intermittent catheterization (CIC) per day were analyzed. Satisfaction was evaluated using a 1-5 scale (where 1 was unsatisfied and 5 was very satisfied) and inquiring patients if they would submit themselves to the procedure again knowing the outcomes. In case of mixed pattern, it was decided to use the main pattern.  All analyses were performed using SPSS 25®.

A total of 50 patients underwent SNM, with a median age of 53 years and 84% (42) were females. Some kind of psychiatric condition was present in 58% (29) of the patients. The most common type of bladder dysfunction pattern was OAB in 52% (26). Of these, a minority had prior treatment with onabotulinum toxin A (12 out of 26). An extra treatment was used in half of the patients, with anticholinergics being the most used treatment in 48% (12), followed by analgesics in 24% (6). Out of the entire cohort, 70% (35) of patients classified their satisfaction as ≥4 and 78% (37) considered they would repeat the treatment in case they needed. The median difference in the number of CICs prior and after SNM implantation, in patients with NOCUR, was -3,47 (±1,95). Concerning overactive bladder, the median reduction in the number of pads was -1,84 (±2,38). Regarding patients using chronic indwelling catheter (7), only 1 maintained the need of catheter after treatment. Clavien-Dindo complications grade ≥3 occurred in 2 (4%) patients, with complete removal of the implant. Concerning patients with urinary symptoms and fecal incontinence, 89% (8) reported improvement in their bowel complaints. No correlation was found between age and level of satisfaction with SNM and female patients presented higher satisfaction with SNM (p=0,012). The difference in the usage of pads before and after SNM implantation correlated with higher satisfaction (p<0,05). Patients with NOCUR reported better results in terms of satisfaction compared to OAB(p=0,015).

SNM shows good effectiveness in both OAB and NOCUR populations, with higher perceived satisfaction in the latest. Female gender correlated with a greater level of satisfaction. Age does not seem to be an important factor in terms of response to treatment. The decrease in the number of pads and CICs used in the OAB and NOCUR populations, respectively, revealed a good response to SNM treatment. As shown by the low number of complications SNM implantation can be considered a safe procedure.

This retrospective study represents our nine years of experience with SNM therapy for bladder dysfunctions. These results show promising responses and high levels of satisfaction in both the OAB and NOCUR populations.

Amundsen CL, Richter HE, Menefee S, Vasavada S, Rahn DD, Kenton K, Harvie HS, Wallace D, Meikle S. The Refractory Overactive Bladder: Sacral NEuromodulation vs. BoTulinum Toxin Assessment: ROSETTA trial. Contemp Clin Trials. 2014 Mar;37(2):272-83. doi: 10.1016/j.cct.2014.01.009. Epub 2014 Jan 30. PMID: 24486637; PMCID: PMC3989885.
Chartier-Kastler E, et al. Sacral Neuromodulation with the InterStim™ System for Intractable Lower Urinary Tract Dysfunctions (SOUNDS): Results of Clinical Effectiveness, Quality of Life, Patient-Reported Outcomes and Safety in a French Multicenter Observational Study. Eur Urol Focus. 2021 Nov;7(6):1430-1437. doi: 10.1016/j.euf.2020.06.026. Epub 2020 Sep 7. PMID: 32907782.