What uro-gynecologists should know about sacral neuromodulation (SNM) for the treatment of refractory overactive bladder

Sacral neuromodulation treatment for urinary voiding dysfunctions: results of treatment with the largest single-center series in a tertiary referral center in Turkey

BACKGROUND

Sacral neuromodulation (SNM) is a minimally invasive treatment that modulates spinal reflexes to regulate bladder, urinary sphincter, and pelvic floor and has successfully been used in the treatment of refractory voiding dysfunctions. The aim of this study was to present our experience with SNM in a tertiary referral center with the largest number of patients and review the safety and efficacy of the procedure.

METHODS

A total of 42 patients with refractory lower urinary tract symptoms were included into the study. After an initial test period, patients who showed more than 50% improvement in their symptoms underwent the second stage of SNM. Twelve patients had overactive bladder (OAB), bladder pain syndrome/interstitial cystitis (BPS/IC) and 17 had urinary retention. The clinical success was examined during follow-up by voiding diary, urodynamics, and global response assessment.

RESULTS

Between February 2015 and December 2020, a total of 29 patients underwent stages I&II SNM procedures. The mean ages of patients in OAB/BPS group and retention group were 40 (37-57 years) and 35 (27-44 years), respectively. Mean follow-up time was at least 1 year. Overall, 58.5% success rate was observed in OAB, BPS/IC, and urinary retention groups. Global response assessment score in both groups increased significantly (p = 0.001). No statistically significant difference was found between success or failure rates when sex and age were variable parameters (p > 0.05).

DISCUSSION

SNM appears to be an effective and safe treatment option in restoring voiding dysfunctions in patients with refractory idiopathic and neurogenic voiding dysfunctions. Our initial series revealed favorable results; however, further studies with larger series and longer follow-up are needed.

Physical Agent-Based Treatments for Overactive Bladder: A Review

Almost one-fifth of the people in the world experience a decrease in quality of life due to overactive bladder (OAB) syndrome. The main bothersome symptoms are urgency accompanied by urinary frequency and nocturia. This chronic, disabling condition is first managed by reducing fluid intake and pelvic floor muscle training, supplemented with antimuscarinic drugs, if necessary. However, refractory cases often still occur. In more severe cases, invasive surgical interventions can be considered; yet, the success rate is still inconsistent, and there is a high complication rate. This condition is frustrating for patients and challenging for the medical staff involved. Although its pathophysiology has not been fully elucidated, peripheral autonomic somatic and sensory afferent receptors are considered to be involved in this condition. Hence, currently, physical agent-based treatments such as neuromodulation have taken a significant place in the third-line therapy of OAB. The efficacy and safety profiles of electrical and magnetic stimulation continue to evolve. Physical-based agents provide an appealing option owing to their effectiveness and minimal side effects. In addition, more physical therapies using light and shock energy are currently being investigated. Thus, a comprehensive understanding of these modalities is an extremely important aspect to provide the most suitable modalities for patients.

Sacral Neuromodulation in Pregnant Women—A Case Report and Literature Review

Millions of women around the world suffer from an overactive bladder and urinary retention. A significant number of them are of reproductive age. For 25 years, SNM has been an effective therapy for treatment-resistant hyperactive bladder and idiopathic urinary retention. The paper presents a case of a 35-year-old pregnant woman with an overactive bladder resistant to pharmacological treatment, who responded positively to sacral neuromodulation. The patient decided against deactivating the neuromodulator and, after an uneventful course of pregnancy, she gave birth by a caesarean section to a healthy female infant. The use of SNM in pregnant patients remains a constant clinical challenge. The current literature was reviewed, but published studies do not provide a clear answer. Further studies with a long follow-up period are necessary to determine more accurately the effects of SNM therapy on the fetus and the course of pregnancy. Currently, it is recommended to deactivate SNM during pregnancy. However, it seems that an individual approach to the patient with information on the risks and benefits of continuing or discontinuing therapy should be the current procedure.

Medium-term outcomes of sacral neuromodulation in patients with refractory overactive bladder: A retrospective single-institution study

Background

Sacral neuromodulation (SNM) is a minimally invasive fully reversible therapy that was approved in 1997 for overactive bladder syndrome (OAB) refractory to behavior modification and pharmacotherapy. Despite being in use for over two decades, the data on medium to long-term safety and efficacy of SNM in OAB is limited. We investigated the medium-term efficacy and safety of SNM along with the predictive factors for its success in patients with refractory OAB.

Methods

A retrospective consecutive case series of 66 patients undergoing SNM for refractory OAB between July 2009 and July 2018. All patients underwent a test period followed by permanent implantation, if there was > = 50% improvement in any symptom. The primary outcome was “success” defined as > = 50% improvement in any clinical parameter based on the subjective assessment of patient’s response. The secondary outcomes were number of pads used in 24 hours, post-operative complications and re-operation rates.

Results

66 females with an average age of 62.7 years were included. 55/66 patients (83.3%) had a successful test phase and underwent permanent implantation. After a median follow-up of 32 months, SNM was successful in 41/55 (74.5%) patients. Mean number of pads used in 24 hours decreased significantly from 3.5 preoperatively to 1.2 at last follow-up (p<0.001). 8/55 (14.5%) patients reported complications of pain, lead migration, wound dehiscence and device malfunction. 10/55 (18.2%) patients underwent revision surgeries after a median duration of 21.9 months. Device was explanted in 15/55 (27.3%) patients after a median duration of 24 months. No significant predictor for success was identified.

Conclusions

The success rate of SNM is 75% with a complication rate of 14.5% after a median follow-up of ~3 years. This study suggests medium-term efficacy and safety but a high re-operation rate of SNM in patients with refractory OAB.

Attenuated BK channel function promotes overactive bladder in a rat model of obesity

Overactive bladder (OAB) is mostly observed in obese individuals, and is associated with enhanced excitability and contractility of the detrusor smooth muscle (DSM). Large-conductance voltage- and Ca²⁺-activated K⁺ (BK) channels reduce the excitability and contractility of the DSM. We tested whether obesity-induced OAB is associated with altered BK channel expression and activity in the DSM. Seven-week-old female Sprague-Dawley rats (N=80) were fed a normal or high-fat diet (HFD) for 12 weeks. HFD-fed rats exhibited a higher average bodyweight and urodynamically established detrusor overactivity. mRNA levels of the Kcnma1 (BKα subunit) and Kcnmb1 (BKβ1 subunit) in whole tissues and cells from the DSM were reduced in HFD-fed rats. A selective BK channel opener, NS1619, was then applied to DSM cells from the two groups of rats. Patch-clamp techniques revealed that spontaneous transient outward currents, NS1619-induced activation of spontaneous transient outward currents, and whole-cell BK currents, as well as NS1619-induced membrane hyperpolarization, were attenuated in DSM cells from HFD-fed rats. The relaxation effect of NS1619 on contractility was reduced in DSM strips from HFD-fed rats. Thus, impaired expression of Kcnma1 and Kcnmb1 in the DSM contributes to obesity-induced OAB, suggesting that BK channels could be a useful treatment targets in OAB.