EFFECTIVENESS OF SACRAL NEUROMODULATION IN THE MANAGEMENT OF REFRACTORY BLADDER PAIN SYNDROME

INTRODUCTION AND AIM OF THE STUDY Bladder Pain Syndrome (BPS) is a complex, under-diagnosed invalidating pathology. It is difficult to estimate BPS prevalence, because this condition is underestimated. A survey estimated the prevalence of BPS symptoms among adult females in the USA to be 7% [1], whereas Chronic Pelvic Pain symptoms show an incidence overlapping to migraine, asthma and lumbago [2]. Treatment of BPS symptoms is an actual therapeutic challenge and needs a multi-disciplinary management. Paracetamol, NSAID's, antidepressant and anti-convulsivants are the first line treatment; in refractory patients, capsaicin, Transcutaneous Electrical Nerve Stimulation (TENS) and sacral neuromodulation (SNM) may be further options. SNM can reduce BPS symptoms and improves voids and over 90% of patients treated with neuromodulation would undergo the implant again [3]. The aim of this study was to evaluate the effectiveness of SNM for the treatment of symptoms in patients with refractory BPS. MATERIALS AND METHODS A retrospective chart review was performed of patients with BPS, refractory to medical/conservative therapy, who underwent InterStim® unilateral sacral neuromodulation implant between March 2012 and July 2014 in a single Italian centre. All patients were affected by BPS according to the diagnostic criteria (pelvic pain>6 months, with pressure or discomfort to the bladder, associated to at least one of lower urinary tract symptoms (LUTS). All patients were non responders to oral or endovesical therapy; all patients were>18 year-old and a complete work-up was conducted, in order to exclude organic causes of BPS. Patients with pelvic organ prolapse, stress urinary incontinence or neurologic disease were excluded from the treatment. Bladder pain was assessed with Visual Analogue Scale (VAS) before the treatment, one year after the treatment and at the last follow-up visit. LUTS were evaluated using a three-day bladder diary before the treatment, one year after and in the last follow-up visit. All complications were recorded. RESULTS Twenty-three patients (18 women, and 5 men) underwent first stage unilateral S3 stimulation; median age was 56 years (range 43–75 years) and mean follow-up was 32 months. Average symptoms duration was 2.5 years (range 1–6.5); 78% of the patients (only women) showed a significant improvement (≥50% relief of pain and LUTS) and underwent a definitive implant, In all patients, the implantable pulse generator (IPG) was placed in a subcutaneous pouch in the gluteal region, on the right side in 85% of cases. Baseline and post-treatment VAS and parameters of the bladder diary were compared, showing significant improvements. Patients' reported an average pain score decreased from a mean of 8 (9–10) at baseline to 3 (2–5) at one-year follow-up (p < 0.001). Urgency decreased from 4.6 ± 2.4 up to 1.3 ± 1.9 (p < 0.001). Daily urinary frequency improved from 12.7 ± 4.8 times up to 8.7 ± 2.8 (p < 0.001) and nocturia decreased from 2.5 ± 1.9 up to 0.7 ± 1 (p < 0.001). Mean voided volume increased from 145.4 ± 70.5 ml to 208.2 ± 73.4 ml (p < 0.001). Clinical effectiveness was maintained in the last follow-up visit. There were no cases of: infection, pain at the site of implantation, replacement of IPG due to ended battery life. INTERPRETATION OF RESULTS Although literature studies are at high risk of bias and are difficult to compare, due to the different NMS techniques, evaluation of the outcomes and patient selection, our results are at least overlapping with the literature data. CONCLUSIONS Sacral neuromodulation appears to be effective and safe in treating refractory BPS with LUTS associated. Our study provides further evidence for the role of this therapy in BPS, an invalidating pathology with a major impact on patients' quality of life and that is difficult to diagnose and to treat.