Sacral Neuromodulation: Mechanism of Action

Recent Developments in On-Demand Voiding Therapies

One cannot survive without regularly urinating and defecating. People with neurologic injury (spinal cord injury, traumatic brain injury, stroke) or disease (multiple sclerosis, Parkinson's disease, spina bifida) and many elderly are unable to voluntarily initiate voiding. The great majority of them require bladder catheters to void urine and "manual bowel programs" with digital rectal stimulation and manual extraction to void stool. Catheter-associated urinary tract infections frequently require hospitalization, whereas manual bowel programs are time consuming (1 to 2 hours) and stigmatizing and cause rectal pain and discomfort. Laxatives and enemas produce defecation, but onset and duration are unpredictable, prolonged, and difficult to control, which can produce involuntary defecation and fecal incontinence. Patients with spinal cord injury (SCI) consider recovery of bladder and bowel function a higher priority than recovery of walking. Bladder and bowel dysfunction are a top reason for institutionalization of elderly. Surveys indicate that convenience, rapid onset and short duration, reliability and predictability, and efficient voiding are priorities of SCI individuals. Despite the severe, unmet medical need, there is no literature regarding on-demand, rapid-onset, short-duration, drug-induced voiding therapies. This article provides in-depth discussion of recent discovery and development of two candidates for on-demand voiding therapies. The first, [Lys3,Gly8,-R-γ-lactam-Leu9]-NKA(3-10) (DTI-117), a neurokinin2 receptor agonist, induces both urination and defecation after systemic administration. The second, capsaicin (DTI-301), is a transient receptor potential cation channel subfamily V member 1 (TRPV1) receptor agonist that induces defecation after intrarectal administration. The review also presents clinical studies of a combination drug therapy administered via iontophoresis and preclinical studies of neuromodulation devices that induce urination and defecation. SIGNIFICANCE STATEMENT: A safe and effective, on-demand, rapid-onset, short-duration, drug-induced, voiding therapy could eliminate or reduce need for bladder catheters, manual bowel programs, and colostomies in patient populations that are unable to voluntarily initiate voiding. People with spinal injury place more importance on restoring bladder and bowel control than restoring their ability to walk. This paradigm-changing therapy would reduce stigmatism and healthcare costs while increasing convenience and quality of life.

[Neurogenic, non-obstructive urinary retention: diagnosis and treatment]

Neurogenic, non-obstructive urinary retention has a varied aetiology. The condition can be caused by central-nervous diseases as well as by disorders of the peripheral nervous system. The formation of residual urine may lead to considerable problems that can have a significant impact on a patient's everyday life. A treatment appropriate for the lower urinary tract dysfunction and suited to the patient's situation in life is only possible if a differentiated diagnostic evaluation has been performed. Both conservative and surgical therapeutic strategies are available, while drug treatment approaches are less relevant. Neuromodulative procedures are particularly suitable for causal treatment of the dysfunction. For patients requiring artificial bladder voiding, intermittent self-catheterization is generally preferable to using an indwelling catheter.

Burst Stimulation Evokes Increased Bladder and Urethral Pressure in Patients With Sacral Neuromodulation, Indicating Potential Activation of the Autonomic Nervous System: A Pilot Study

OBJECTIVES

Currently, sacral neuromodulation (SNM) outcomes are often suboptimal, and changing stimulation parameters might improve SNM efficacy. Burst stimulation mimics physiological burst firing of the nervous system and might therefore benefit patients treated with SNM. The purpose of the present pilot study was to evaluate the effect of various Burst SNM paradigms on bladder and urethral pressure in patients with overactive bladder (OAB) or nonobstructive urinary retention (NOUR).

MATERIALS AND METHODS

The bladder was filled to 50% of its capacity under general anesthesia in six patients with an implanted sacral lead for SNM purposes. Bladder pressure, and mid- and proximal urethral pressure were measured using conventional (Con-) SNM and various Burst SNM paradigms (10-20-40 Hz interburst frequency) with increasing amplitudes up to 5 mA for Con-SNM and 4 mA for Burst SNM.

RESULTS

Burst SNM caused a substantial increase in both bladder and urethral pressure. In contrast, Con-SNM caused a milder increase in urethral pressure, and only one patient showed a modest increase in bladder pressure. Furthermore, the pressure increase was higher in the proximal urethra than in the midurethra using Burst-SNM, whereas Con-SNM caused comparable increases in proximal and midurethra pressure.

CONCLUSIONS

Burst SNM induces bladder contraction compared with Con-SNM and induces higher pressure increases in bladder and proximal urethra than does Con-SNM in patients with OAB or NOUR, indicating a higher degree of autonomic nervous system stimulation. The observed responses could not be fully explained by the total charge of the Burst SNM paradigms, which suggests the importance of individual Burst SNM parameters, such as frequency and amplitude. Future studies should assess the feasibility and efficacy of Burst SNM in awake patients.

Early Sacral Neuromodulation Prevented Detrusor Overactivity in Rats With Spinal Cord Injury

OBJECTIVES

Sacral neuromodulation (SNM) has been shown to alleviate bladder dysfunction in patients with overactive bladder and nonobstructive urinary retention. However, the therapeutic effect and mechanism of SNM in neurogenic bladder dysfunction are still not fully understood. Using a rat model of spinal cord injury (SCI), this study aims to investigate the therapeutic effect of early SNM in the bladder-areflexia phase on neurogenic bladder dysfunction and evaluate its possible mechanism.

MATERIALS AND METHODS

Basic physiological parameters such as body/bladder weight, blood pressure, and electrocardiogram results were measured to evaluate the safety of SNM. Enzyme-linked immunosorbent assays and quantitative real-time polymerase chain reaction were used to examine the expression of proinflammatory factors. Hematoxylin and eosin and Masson's trichrome staining were used to observe morphological changes, and cystometry was used to evaluate urodynamic changes after SNM treatment. Western blotting and immunofluorescence staining were used to measure the levels of transient receptor potential vanilloid 1 (TRPV1) and calcitonin gene-related peptide (CGRP) in the L6-S1 dorsal root ganglia (DRGs) and bladder. Capsaicin desensitization was used to investigate whether inhibiting TRPV1 could prevent detrusor overactivity in SCI rats.

RESULTS

Early SNM did not affect the body/bladder weight, heart rate, blood pressure, or the expression of proinflammatory cytokines (PGE2, IL-1, IL-2, IL-6, TGF-β, or TNF-α) in the bladders of SCI rats. Morphologically, early SNM prevented urothelial edema (p = 0.0248) but did not influence collagen/smooth muscle in the bladder. Compared with untreated rats with SCI, the rats treated with SNM exhibited increased bladder capacity (p = 0.0132) and voiding efficiency (p = 0.0179), and decreased nonvoiding contraction (NVC) frequency (p = 0.0240). The maximum pressure, basal pressure, postvoid residual, and NVC amplitude did not change significantly. After the SNM treatment, the expression of TRPV1 in the bladder and CGRP in L6-S1 DRGs weredecreased (L6, p = 0.0160; S1, p = 0.0024) in SCI rats. In capsaicin-desensitized SCI rats, urodynamic results showed an increase in bladder capacity (p = 0.0116) and voiding efficiency (p = 0.0048), and diminished NVC frequency (p = 0.0116), while other parameters did not change significantly.

CONCLUSIONS

Early SNM prevented urothelial edema morphologically and detrusor overactivity in SCI rats. Inhibition of TRPV1 in the bladder and DRGs may be one of the potential mechanisms for preventing detrusor overactivity by SNM.

Case report: Sacral neuromodulation for neurogenic lower urinary tract dysfunction in patient with neuronal intranuclear inclusion disease

Neuronal intranuclear inclusion disease is an uncommon neurodegenerative disorder. The diagnosis of this condition has become more definitive based on current research. However, treatment options remain limited. Neurogenic lower urinary tract dysfunction is one of the prevalent and significant complications, which is the result of its multi-system effects. Here, we present the case of a 48-year-old man diagnosed with neuronal intranuclear inclusion disease based on existing evidence and was complicated by neurogenic lower urinary tract dysfunction. Despite undergoing some medical treatments, his lower urinary tract symptoms, including urinary incontinence, incomplete or intermittent voiding, etc, continued to worsen while upper urinary tract injury developed. Based on careful consideration of the patient's condition and the available findings, we performed an unprecedented sacral neuromodulation on him. Implementation of sacral neuromodulation led to significant improvement in his urination function and alleviate kidney function damage. Our case suggests a potential therapeutic role for sacral neuromodulation in the treatment of neurogenic lower urinary tract dysfunction associated with neuronal intranuclear inclusion disease. Additional research is required to determine the effectiveness of sacral neuromodulation in managing neurogenic lower urinary tract dysfunction caused by various etiologies.

Preliminary analysis of stimulation parameters for sacral neuromodulation in different indications: a multicenter retrospective cohort study from China

BACKGROUND

Sacral neuromodulation (SNM) is an effective approach for treating lower urinary tract dysfunction (LUTD), and stimulation programming is essential for successful treatment. However, research on SNM programming for various indications is limited. Thus, the authors aimed to determine whether there were differences in the stimulation parameters for different SNM indications and the appropriate programming recommendations.

MATERIALS AND METHODS

Clinical data were retrospectively collected from patients with LUTD who underwent SNM and completed internal pulse generator implantation. The parameters with the highest patient satisfaction or the most symptom improvement during the test period were considered optimal and used to set the programming after internal pulse generator implantation.

RESULTS

After screening, 282 patients were enrolled and categorized into four groups based on the following indications: refractory overactive bladder (OAB) ( n =61), neurogenic lower urinary tract dysfunction (nLUTD) ( n =162), interstitial cystitis/painful bladder syndrome (IC/BPS) ( n =24), and idiopathic nonobstructive urinary retention (NOUR) ( n =35). When analyzing the optimal stimulus parameters, disparities in the stimulation amplitude and pulse frequency were noted among the four groups. The stimulation amplitude in the nLUTD group was higher than that in the idiopathic NOUR group ( P =0.013). Differences in pulse frequency were observed between the refractory OAB and nLUTD groups ( P <0.001) and between the refractory OAB and idiopathic NOUR groups ( P =0.001). No differences in the electrode configuration or pulse width settings existed among the four groups.

CONCLUSIONS

The stimulation parameters for SNM varied among the different indications. For the initial programming of stage I, most patients are recommended to start with stimulation amplitudes below 2 V, although patients with nLUTD may benefit from higher amplitudes. A standard pulse width of 210 μs is recommended for all patients. However, for individuals experiencing nLUTD or idiopathic NOUR, the pulse frequency can begin above the standard 14 Hz but not exceed 50 Hz.

Remote programming in stage I sacral neuromodulation: a multicentre prospective feasibility study

OBJECTIVE

Sacral neuromodulation (SNM) has emerged as an effective therapy for refractory lower urinary tract dysfunction (LUTD). Remote programming holds promise in addressing the time and economic burdens associated with outpatient programming, especially for patients in the observation period following Stage I implant surgery (where the lead is implanted first without the pulse generator). The study aimed to explore the effectiveness and patient satisfaction of remote programming for Stage I SNM patients, and analyze the benefits patients gain from remote programming.

METHODS

This prospective study was conducted at multiple high-level clinical SNM centres in China. Patients requiring SNM implantation were enroled and divided into two groups based on patient preference: remote programming (RP) group and outpatient control (OC) group. Patient attitudes toward RP were assessed through questionnaires, and the degree of symptom improvement was compared between the two groups to explore the usability of RP.

RESULTS

A total of 63 participants from 6 centres were included in the study, with 32 belonging to the RP group. The remote programming system presents a high level of usability (98%) and willingness (satisfaction rate: 96.83%) in result of questionnaire. RP showed a significant advantage in improving patients' score of ICSI/ICPI (medianΔICSI/ICPI RP vs. OC= -13.50 vs -2, P =0.015). And slightly ameliorate urinary symptoms such as pain (medianΔVAS RP vs. OC= -1 vs 0, P = 0.164) and urgency (medianΔOBASS -2.5 vs. -1, P = 0.,229), but the difference was not statistically significant. RP did not significantly impact the quality of life of patients ( P =0.113), so do the rate of phase-two conversion ( P = 0.926) or programming parameters.

CONCLUSION

To the best of our knowledge, the presented study is the first multicenter research focusing on the remote programming of Stage I SNM patients. Through the clinical implementation and patient feedback, we demonstrate that remote programming is not inferior to in-person programming in terms of success rate, effectiveness, safety, and patient satisfaction.

Response to tibial and sacral nerve modulation in overactive bladder: Is there any correlation?

OBJECTIVES

To assess the correlation between the response to transcutaneous tibial nerve stimulation (TTNS) and subsequent response to sacral nerve modulation (SNM) to treat overactive bladder (OAB).

MATERIALS AND METHODS

All patients who consecutively received TTNS followed by a two-stage SNM between January 2016 and June 2022 to treat OAB in two university hospital centers were included. The response to each therapy was evaluated with success defined by a 50% or greater improvement in one or more bothersome urinary symptoms from baseline. The primary endpoint was the statistical relationship between the response to TTNS and the response to SNM, assessed by logistic regression. Secondary endpoints were the statistical relationship between the response to TTNS and the response to SNM when controlling for gender, age (<57 years vs. >57 years), presence of an underlying neurological disease, and presence of DO, adding the factor and interaction to the previous regression model.

RESULTS

Among the 92 patients enrolled in the study, 68 of them were women (73.9%), and the median age was 57.0 [41.0-69.0] years. The success was reported in 22 patients (23.9%) under TTNS and 66 patients (71.7%) during the SNM test phase. There was no statistical correlation between response to TTNS and response to SNM in the overall population (confidence interval: 95% [0.48-4.47], p = 0.51). Similarly, there was no statistical correlation when controlling for age <57 years or ≥57 years, with p = 1.0 and p = 0.69, respectively. No statistical study could be conducted for the other subpopulations due to small sample sizes.

CONCLUSION

The response to TTNS does not predict the response to SNM in the treatment of OAB. TTNS and SNM should be considered as separate therapies, and the decision-making process for OAB treatment should take this into account.

Evaluation of the efficacy of sacral neuromodulation in the treatment of voiding dysfunction after endometriosis surgery

Pelvic surgery for endometriosis is associated with a risk of bladder and digestive sequelae. Sacral neuromodulation (SNM) has been shown to be effective in the treatment of overactive bladder (OAB) and voiding dysfunction (VD). This study aimed to evaluate the efficacy of sacral neuromodulation (SNM) in treating voiding dysfunction (VD) following endometriosis surgery. A retrospective analysis was conducted on data from women who underwent SNM testing for persistent VD after endometriosis surgery. The study included 21 patients from a French tertiary referral center. Patient characteristics, lower urinary tract symptoms, urodynamic findings, SNM procedures, and outcomes were assessed. The primary outcome was the success of SNM treatment for VD. After a median follow-up of 55 months, 60% of patients achieved successful outcomes, with significant improvements of VD and quality of life. Moreover, more than half of patients who required clean intermittent self-catheterization (CISC) before SNM were able to wean off CISC. Complications such as infections and paraesthesia were observed, but overall, SNM was found to be effective and well tolerated. Age and the interval between endometriosis surgery and SNM testing were associated with treatment success. This study adds to the limited existing literature on SNM for VD after endometriosis surgery and suggests that SNM can be a valuable therapeutic option for these patients. Further research is needed to identify predictive factors and mechanisms underlying the effectiveness of SNM in this context. MRI-compatible and rechargeable devices, has improved the feasibility of SNM for these patients. In conclusion, SNM offers promise as a treatment option for persistent VD after endometriosis surgery, warranting further investigation. LEVEL OF EVIDENCE: 4.

Development and Validation of an IoT Neurostimulator for the Treatment of Neurogenic Bladder

Neurogenic bladder is a dysfunction in the lower urinary tract due to damage to the nervous system. One of the treatments that has shown important results is transcutaneous neuromodulation. The neuromodulation equipment available on the market does not allow remote activation or offer many resources for adjusting the parameters of the generated stimulus, as most devices operate with pre-established parameters in closed packages. For this reason, customizing therapy for each individual can be difficult. Therefore, the objective was to develop and validate a neuromodulation device capable of being remotely programmed and properly monitored. Materials and methods for validating devices were used according to the Brazilian Regulatory Standard (NBR), which deals with general requirements for the basic safety and essential performance of electromedical devices. After verifying the reliability of the device, which was capable of generating a biphasic and symmetrical wave, measured by an oscilloscope, considered safe by the technical requirements, it was tested in a real application. Users reported feeling a comfortable stimulus, similar to other previously used devices, and considered the device easy to use. In this way, it was possible to demonstrate the reliability and validity of the developed device.

Development of a predictive tool for sacral nerve modulation implantation in the treatment of non-obstructive urinary retention and/or slow urinary stream: a study from the Neuro-Urology Committee of the French Association of Urology

PURPOSE

This study aimed to seek predictive factors and develop a predictive tool for sacral nerve modulation (SNM) implantation in patients with non-obstructive urinary retention and/or slow urinary stream (NOUR/SS).

METHODS

This study was designed as a retrospective study including all patients who have undergone a two-stage SNM for NOUR/SS between 2000 and 2021 in 11 academic hospitals. The primary outcome was defined as the implantation rate. Secondary outcomes included changes in bladder emptying parameters. Univariate and multivariable logistic regression analysis were performed and determined odds ratio for IPG implantation to build a predictive tool. The performance of the multivariable model discrimination was evaluated using the c-statistics and an internal validation was performed using bootstrap resampling.

RESULTS

Of the 357 patients included, 210 (58.8%) were finally implanted. After multivariable logistic regression, 4 predictive factors were found, including age (≤ 52 yo; OR = 3.31 CI95% [1.79; 6.14]), gender (female; OR = 2.62 CI95% [1.39; 4.92]), maximal urethral closure pressure (≥ 70 cmH2O; OR: 2.36 CI95% [1.17; 4.74]), and the absence of an underlying neurological disease affecting the lower motor neuron (OR = 2.25 CI95% [1.07; 4.76]). Combining these factors, we established 16 response profiles with distinct IPG implantation rates, ranging from 8.7 to 81.5%. Internal validation found a good discrimination value (c-statistic, 0.724; 95% CI 0.660-0.789) with a low optimism bias (0.013). This allowed us to develop a predictive tool ( https://predictivetool.wixsite.com/void ).

CONCLUSION

The present study identified 4 predictive factors, allowing to develop a predictive tool for SNM implantation in NOUR/SS patients, that may help in guiding therapeutic decision-making. External validation of the tool is warranted.

[Therapeutic value of neuromodulation in women]

BACKGROUND

Neuromodulative treatment for the treatment of overactive bladder has been used in clinical practice since its introduction in the early 1980s.

OBJECTIVES

Description and update of the various neuromodulative techniques (tibial nerve stimulation, sacral and pudendal neuromodulation), presentation of their effectiveness and safety, and evaluation of their evidence for clinical practice.

MATERIALS AND METHODS

Literature search in PubMed and Embase, inclusion of studies according to the following criteria: evidence level, timeliness, length of follow-up and number of female patients according to the author's preference.

RESULTS

The efficacy and safety of both percutaneous tibial nerve stimulation (PTNS) and sacral neuromodulation (SNM) has been proven by studies with an evidence level of 1. Long-term data of up to 20 years are available for SNM, while long-term data for PTNS are limited. Permanent implants for tibial nerve stimulation are promising new developments. Pudendal neuromodulation (PNM) is suitable for more complex indications but is surgically more challenging.

CONCLUSIONS

Both PTNS and SNM are suitable for broad application in clinical practice. PTNS can be offered as an alternative to pharmacotherapy, while SNM provides the most convincing clinical data of all neuromodulative therapies.

Sacral Neuromodulation Using a Novel Device with a Six-contact-point Electrode for the Treatment of Patients with Refractory Overactive Bladder: A Multicenter, Randomized, Single-blind, Parallel-control Clinical Trial

BACKGROUND

A novel sacral neuromodulation system (SacralStim) which has an electrode with six contact points was recently designed.

OBJECTIVE

To evaluate the effectiveness and safety of the SacralStim system for treating patients with refractory overactive bladder (OAB).

DESIGN, SETTING, AND PARTICIPANTS

This was a multicenter, randomized, single-blind clinical trial. Patients with refractory OAB were enrolled from January 2018 to May 2020.

INTERVENTION

Participants were randomly allocated to the treatment group (SNM on) or the control group (SNM off) for a single-blind period of 12 ± 2 wk.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary outcome was the percentage of patients with a reduction in the average number of voids/24 h of at least 50% at the 12-wk follow-up visit. Other follow-up evaluations, including voiding diary outcomes, questionnaires on Overactive Bladder Symptom Score (OABSS), quality of life (QoL), device satisfaction, and causes of adverse events (AEs), were performed over the first 48 wk after implantation.

RESULTS AND LIMITATIONS

The therapeutic success rate at 12 wk was 56.76% in the treatment group and 11.11% in the control group (p < 0.001). There were significant differences in voiding diary variables between the two groups, including changes in the average number of voids/24 h, micturition volume/void, and improvement in the urge incontinence ratio. No severe AEs occurred. A limitation is the sham stimulation used as a control in the study. A head-to-head study is required to make a direct comparison of devices with six and four contact points.

CONCLUSIONS

This clinical trial provides strong evidence that patients with refractory OAB benefit from the novel SacralStim system. More research is required for direct comparison of the SacralStim system with traditional four-contact-point devices.

PATIENT SUMMARY

This study confirms the effectiveness and safety of a novel SacralStim system that stimulates the sacral nerve for treatment of overactive bladder. The system has an electrode with six contact points and can provide more programming options after implantation.

Comparison of different types of therapy for overactive bladder: A systematic review and network meta-analysis

To compare the efficacy and safety of different interventions [including antimuscarinics, mirabegron, OnabotulinumtoxinA, sacral neuromodulation (SNM) and peripheral tibial nerve stimulation (PTNS)] for treating idiopathic overactive bladder (OAB). PubMed, Embase, Cochrane Library, and other sources were searched for randomized controlled trials (RCTs) comparing interventions for overactive bladder from 1 January 2000 to 19 April 2021. A systematic review and network meta-analysis were performed by two authors independently. Fifty-five RCTs involving 32,507 patients were included in this analysis. Overall, antimuscarinics, mirabegron, OnabotulinumtoxinA, sacral neuromodulation, and peripheral tibial nerve stimulation were more efficacious than placebo, and sacral neuromodulation showed the best effect for reducing micturition frequency, urgency episodes and urgency urinary incontinence episodes. OnabotulinumtoxinA was the best intervention for achieving reductions of 100 and ≥50% in the number of urinary incontinence episodes/day, and peripheral tibial nerve stimulation was the best intervention for reducing urinary incontinence episodes. Antimuscarinics, mirabegron and peripheral tibial nerve stimulation had a similar efficacy for reducing micturition frequency, urinary incontinence episodes and urgency urinary incontinence episodes. The results revealed that all interventions examined herein were efficacious for managing adult overactive bladder syndrome compared with placebo. Furthermore, sacral neuromodulation and OnabotulinumtoxinA were the most efficient treatments for overactive bladder.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=251966], identifier [CRD42021251966].

Implementation of sacral neuromodulation for urinary indications. A Danish prospective study during the initial 15 months of a new service in a tertiary referral hospital

OBJECTIVE

Sacral neuromodulation (SNM) is a well-established treatment modality for idiopathic overactive bladder and urgency incontinence, idiopathic fecal incontinence and non-obstructive urinary retention. This study describes the start-up phase of establishing the SNM service. Primary objective: To investigate the patient-reported outcome measures of SNM on lower urinary tract dysfunction symptoms. Secondary objectives: To investigate bowel function, sexual satisfaction and to monitor SNM safety.

MATERIALS AND METHODS

Twenty-two patients with refractory idiopathic and neurogenic lower urinary tract dysfunction were offered a two-stage test-phase procedure and SNM device implantation. On completing the study, the patients rated their satisfaction with the treatment using a five-point Likert scale and a bother score of urinary, bowel and sexual symptoms on a scale of 1-10 (the worst). Their complications were assessed.

RESULTS

Nineteen patients (86%) were responders during the test phase and had the pulse generator implanted. Seventeen patients were very satisfied/satisfied. A statistically significant change in urinary symptoms bother score was observed in the idiopathic and neurogenic patients, a reduction from 10 to 4 (p = .0057) and 10 to 3 (p = .014), respectively. Eleven patients (58%) had symptoms from two or three pelvic compartments. Nine patients (47%) had complications. All but one event was resolved.

CONCLUSIONS

SNM is safe in this heterogeneous group of patients with refractory lower urinary tract dysfunction of various etiologies. A substantial improvement was observed in the pelvic organ dysfunction, demanding a multidisciplinary approach. More studies are required to standardize the evaluation of the subjective and objective outcomes of SNM.

Data Gap in Sacral Neuromodulation Documentation: Call to Improve Documentation Protocols

Purpose: We quantified patient record documentation of sacral neuromodulation (SNM) threshold testing and programming parameters at our institution to identify opportunities to improve therapy outcomes and future SNM technologies.Methods: A retrospective review was conducted using 127 records from 40 SNM patients. Records were screened for SNM documentation including qualitative and quantitative data. The qualitative covered indirect references to threshold testing and the quantitative included efficacy descriptions and device programming used by the patient. Findings were categorized by visit type: percutaneous nerve evaluation (PNE), stage 1 (S1), permanent lead implantation, stage 2 (S2) permanent impulse generator implantation, device-related follow-up, or surgical removal.Results: Documentation of threshold testing was more complete during initial implant visits (PNE and S1), less complete for S2 visits, and infrequent for follow-up clinical visits. Surgical motor thresholds were most often referred to using only qualitative comments such as “good response” (88%, 100% for PNE, S1) and less commonly included quantitative values (68%, 84%), locations of response (84%, 83%) or specific contacts used for testing (0%). S2 motor thresholds were less well documented with qualitative, quantitative, and anatomical location outcomes at 70%, 48%, and 36% respectively. Surgical notes did not include specific stimulation parameters or contacts used for tests. Postoperative sensory tests were often only qualitative (80%, 67% for PNE, S1) with quantitative values documented much less frequently (39%, 9%) and typically lacked sensory locations or electrode-specific results. For follow-up visits, <10% included quantitative sensory test outcomes. Few records (<7%) included device program settings recommended for therapy delivery and none included therapy-use logs.Conclusions: While evidence suggests contact and parameter-specific programming can improve SNM therapy outcomes, there is a major gap in the documentation of this data. More detailed testing and documentation could improve therapeutic options for parameter titration and provide design inputs for future technologies.

Novel electrode design reduces sensory threshold current drift during peripheral nerve evaluation in patients considered for sacral nerve stimulation

Objective:

To retrospectively compare the efficacy and technical performance of a novel lead used for percutaneous nerve evaluation (PNE) during the testing phase for sacral nerve neuromodulation with the existing lead currently used.

Materials and methods:

Sixty-three PNE leads were inserted in 45 consecutive patients who underwent PNE with the novel helical electrodes, and the intra-operative and return clinic sensory threshold currents were recorded. This resulted in current measurements for 63 individual electrodes. Measurements were compared with 46 consecutive patients who previously underwent PNE using the standard lead with measurements for 63 individual electrodes. Current difference distributions for the two leads were compared using a Wilcoxon signed-rank test.

Results:

There was a statistically significant difference observed between the two types of PNE electrode. The new PNE lead demonstrated less drift in sensory threshold current during a 12-day test period in comparison to the old lead.

Conclusion:

The novel helical PNE electrodes demonstrate a significant improvement in current drift compared with the old style leads over a 12-day test period.

Level of evidence:

Level III

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 of bladder underactivity induced by prolonged pudendal afferent firing in cats

This study examined the effect of sacral neuromodulation on persistent bladder underactivity induced by prolonged pudendal nerve stimulation (PudNS). In 10 α-chloralose-anesthetized cats, repetitive application of 30-min PudNS induced bladder underactivity evident as an increase in bladder capacity during a cystometrogram (CMG). S1 or S2 dorsal root stimulation (15 or 30 Hz) at 1 or 1.5 times threshold intensity (T) for inducing reflex hindlimb movement (S1) or anal sphincter twitch (S2) was applied during a CMG to determine if the stimulation can reverse the bladder underactivity. Persistent (>3 h) bladder underactivity consisting of a significant increase in bladder capacity to 163.1 ± 11.3% of control was induced after repetitive (1-10 times) application of 30-min PudNS. S2 but not S1 dorsal root stimulation at 15 Hz and 1 T intensity reversed the PudNS-induced bladder underactivity by significantly reducing the large bladder capacity to 124.3 ± 12.9% of control. Other stimulation parameters were not effective. After the induction of persistent underactivity, recordings of reflex bladder activity under isovolumetric conditions revealed that S2 dorsal root stimulation consistently induced the largest bladder contraction at 15 Hz and 1 T when compared with other frequencies (5-40 Hz) or intensities (0.25-1.5 T). This study provides basic science evidence consistent with the hypothesis that abnormal pudendal afferent activity contributes to the bladder underactivity in Fowler's syndrome and that sacral neuromodulation treats this disorder by reversing the bladder inhibition induced by pudendal nerve afferent activity.

Does response to percutaneous tibial nerve stimulation predict similar outcome to sacral nerve stimulation?

AIMS

Percutaneous tibial nerve stimulation (PTNS) is a simple neuromodulation technique to treat an overactive bladder. It is unclear whether the response to PTNS would suggest a similar response to sacral nerve stimulation (SNS), and whether PTNS could be utilized as an alternative test phase for an SNS implant. This study assessed whether PTNS response was a reliable indicator for subsequent SNS trials.

METHODS

We performed a retrospective review of the hospital databases to collect all patients who had PTNS and who subsequently had an SNS trial in two tertiary hospitals from 2014 to 2020. Response to both interventions was assessed. A 50% reduction in overactive symptoms (frequency-volume charts) was considered a positive response. McNemar's tests using exact binomial probability calculations were used. The statistical significance level was set to 0.05.

RESULTS

Twenty-three patients who had PTNS subsequently went on to a trial of SNS. All patients except one had previously poor response to PTNS treatment. Eight of them also failed the SNS trial. However, 15 patients (including the PTNS responder) had a successful SNS trial and proceeded with the second-stage battery implantation. The difference in response rates between the PTNS and SNS trial was statistically significant (p < 0.001).

CONCLUSIONS

Poor response to PTNS does not seem to predict the likelihood of patients responding to SNS. A negative PTNS trial should not preclude a trial of a sacral nerve implant. The predictive factors for good and poor responses will be the subject of a larger study.

Sacral Acupuncture for Lower Urinary Tract Symptoms: A Systematic Review of Randomized Controlled Trials

Lower urinary tract symptoms (LUTS) associated with storage, voiding, and post-micturition reduce quality of life and cause mental health problems. In traditional medicine, Baliao points have been empirically used to treat urinary system diseases. In this review, randomized controlled trials (RCTs) using sacral acupuncture on Baliao points with sham treatment, other remedies, or other acupoints were retrieved from 8 electronic databases up to June 2021. Sixteen RCTs met the inclusion criteria. The quality of the included studies was assessed using a risk-of-bias (ROB) tool. Most of the evaluation indicators used in the included RCTs showed that sacral acupuncture had a significant therapeutic effect compared with the sham control intervention groups, and other remedies. However, all studies using acupoints (other than the Baliao points) as a control intervention had a “high” ROB and only reported secondary processed information, making it difficult to evaluate the efficacy of sacral acupuncture treatment for LUTS. No serious adverse effects were reported for sacral acupuncture, and only a low number of minor side effects were observed. These results suggest that sacral acupuncture could be considered as an alternative to existing treatments, with the added benefit of low cost. Large-scale, long-term RCTs are required in the future.

Pelvic floor rehabilitation in the treatment of mixed urinary incontinence among women

Background

Mixed urinary incontinence (MUI) is a common underreported problem among females; it has a major effect on patients’ quality of life. Treatment may be difficult since a single modality cannot be enough to alleviate both the urge and the stress symptoms. Biofeedback-assisted pelvic floor muscle training (PFMT) has a great role in strengthening the pelvic floor muscles especially when accompanied by electrical stimulation. Neuromodulation is another safe well-tolerated method that may improve symptoms of female voiding dysfunction. There are no previous studies that assessed the efficacy of biofeedback-assisted pelvic floor muscle training versus two different types of peripheral neuromodulation which are transcutaneous posterior tibial nerve stimulation (TPTNS) and anogenital neuromodulation in the treatment of mixed urinary incontinence among women. The aim of this work is to study the effectiveness of biofeedback-assisted pelvic floor muscle training with electrostimulation versus two different methods of peripheral neuromodulation techniques in the treatment of women with MUI. Patients were subjected to history taking, assessment questionnaires (Questionnaire for female Urinary Incontinence Diagnosis (QUID), Australian Pelvic Floor Questionnaire (PFQ), and International Consultation on Incontinence Questionnaire-Urinary Incontinence-Short Form (ICIQ-UI-SF)), clinical examination, and manometric pressure assessment. The patients were allocated randomly into three groups. Group I received biofeedback-assisted pelvic floor muscle training and faradic electrical stimulation, group II received posterior tibial neuromodulation, and group III received anogenital neuromodulation.

Results

The present study included 68 non-virgin female patients with mixed urinary incontinence. Significant improvement was noticed in the three studied groups on the subjective and objective levels. No statistically significant difference was reported between the studied groups following the different types of intervention.

Conclusions

Biofeedback-assisted pelvic floor muscle training with electrostimulation is as effective as anogenital neuromodulation and posterior tibial neuromodulation in the treatment of mixed urinary incontinence among females.

Trial registration

PACTR, PACTR202107816829078. Registered 29 July 2021 - Retrospectively registered.

Cortical, Spinal, Sacral, and Peripheral Neuromodulations as Therapeutic Approaches for the Treatment of Lower Urinary Tract Symptoms in Multiple Sclerosis Patients: A Review

INTRODUCTION

Multiple sclerosis (MS) is often associated with urological disorders, mainly urinary incontinence and retention, the management of which being necessary to improve patient's quality of life (QOL) and to reduce potential urological complications. Besides the classical treatments based mainly on anticholinergics and/or self-catheterization, several neuromodulation techniques have been tried in recent years to improve these urinary disorders. By this review, we aim at providing an overview of neuromodulation and electrostimulation approaches to manage urinary symptoms in MS patients.

MATERIALS AND METHODS

A literature search using MEDLINE was performed. Only papers in English, and describing the effects of neuromodulation in MS patients, were considered.

RESULTS

A total of 18 studies met inclusion criteria and were reviewed. Of them, four related to sacral neuromodulation (SNM), seven to percutaneous tibial nerve stimulation (PTNS), six to spinal cord stimulation (SCS), and one to transcranial magnetic stimulation (TMS).

DISCUSSION

PTNS and SNM seem to be effective and safe therapeutic options for treating lower urinary tract symptoms in MS patients principally in case of overactive bladder (OAB) symptoms. Similarly, also SCS and TMS have been shown to be effective, despite the very limited number of patients and the small number of studies found in the literature. Interestingly, these techniques are effective even in patients who do not respond well to conservative therapies, such as anticholinergics. Furthermore, given their safety and efficacy, stimulations such as PTNS could be considered as a first-line treatment for OAB in MS patients, also considering that they are often preferred by patients to other commonly used treatments.

Assessment of sacral spinal excitability using stimulus-response curves of the bulbocavernosus reflex

OBJECTIVE

To analyze and quantify sacral spinal excitability through bulbocavernosus reflex (BCR) stimulus-response curves.

METHODS

Thirty subjects with upper motor neuron lesions (UMN) and nine controls were included in this prospective, monocentric study. Sacral spinal excitability was assessed using stimulus-response curves of the BCR, modeled at different bladder filling volumes relative to the desire to void (as defined by the International Continence Society) during a cystometry. Variations in α (i.e. the slope of the stimulus-response curve) were considered as an indicator of the modulation of sacral spinal excitability.

RESULTS

In all subjects, α increased during bladder filling suggesting the modulation of spinal sacral excitability during the filling phase. This increase was over 30% in 96.7% of neurological subjects and 88.9% of controls. The increase was higher before the first sensation to void in the neurological population (163.15%), compared to controls, (29.91%), p < 0.001.

CONCLUSIONS

We showed the possibility of using BCR stimulus-response curves to characterize sacral spinal response with an amplification of this response during bladder filling as well as a difference in this response amplification in patients with UMN in comparison with a control group.

SIGNIFICANCE

BCR, through stimulus-response curves, might be an indicator of pelvic-perineal exaggerated reflex response and possibly a tool for evaluating treatment effectiveness.

Targeted neuromodulation of pelvic floor nerves in aging and multiparous rabbits improves continence

Pelvic floor muscle stretch injury during pregnancy and birth is associated with the incidence of stress urinary incontinence (SUI), a condition that affects 30-60% of the female population and is characterized by involuntary urine leakage during physical activity, further exacerbated by aging. Aging and multiparous rabbits suffer pelvic nerve and muscle damage, resulting in alterations in pelvic floor muscular contraction and low urethral pressure, resembling SUI. However, the extent of nerve injury is not fully understood. Here, we used electron microscopy analysis of pelvic and perineal nerves in multiparous rabbits to describe the extent of stretch nerve injury based on axon count, axon size, myelin-to-axon ratio, and elliptical ratio. Compared to young nulliparous controls, mid-age multiparous animals showed an increase in the density of unmyelinated axons and in myelin thickness in both nerves, albeit more significant in the bulbospongiosus nerve. This revealed a partial but sustained damage to these nerves, and the presence of some regenerated axons. Additionally, we tested whether electrical stimulation of the bulbospongiosus nerve would induce muscle contraction and urethral closure. Using a miniature wireless stimulator implanted on this perineal nerve in young nulliparous and middle age multiparous female rabbits, we confirmed that these partially damaged nerves can be acutely depolarized, either at low (2-5 Hz) or medium (10-20 Hz) frequencies, to induce a proportional increase in urethral pressure. Evaluation of micturition volume in the mid-age multiparous animals after perineal nerve stimulation, effectively reversed a baseline deficit, increasing it 2-fold (p = 0.02). These results support the notion that selective neuromodulation of pelvic floor muscles might serve as a potential treatment for SUI.

Systematic Literature Review and Meta-Analysis of Sacral Neuromodulation (SNM) in Patients with Neurogenic Lower Urinary Tract Dysfunction (nLUTD): Over 20 Years' Experience and Future Directions

INTRODUCTION

Sacral neuromodulation (SNM) has been used in carefully selected patients with neurogenic lower urinary tract dysfunctions (nLUTD) for over two decades.

METHODS

The aim of the current work was to perform a systematic literature review and meta-analysis of studies reporting the safety and effectiveness of SNM in patients with nLUTD (neurogenic detrusor overactivity, non-obstructive urinary retention, or a combination of both). For this purpose a systematic literature research was conducted using Embase (OvidSP), MEDLINE (OvidSP), MEDLINE In-Process Citations & Daily Update (OvidSP), MEDLINE (OvidSP) e-Pub ahead of print, Cochrane Central Register of Controlled Trials (CENTRAL), NIH Clinicaltrials.gov, and WHO International Clinical Trials Registry Platform (ICTRP) between 1998 and March 2020, supplemented by a hand search.

RESULTS

Forty-seven studies were included in the systematic literature review. Twenty-one studies comprising a total of 887 patients were included in the meta-analysis of test SNM. The pooled success rate of SNM test stimulation was 66.2% (95% CI 56.9-74.4). Depending on neurogenic conditions test success rates varied greatly. Twenty-four studies with a total of 428 patients were included in the meta-analysis of permanent SNM. The success rate of pooled permanent SNM was 84.2% (95% CI 77.8-89.0). Among the identified studies, the most common adverse events (AEs) were loss of effectiveness, infection, pain at implant site, and lead migration with AE rates of 4.7%, 3.6%, 3.2%, and 3.2%, respectively. Limitations entail lower level of evidence (Oxford classification 3-4) of included studies, significant risk of bias, small sample sizes in some studies, the inclusion of retrospective case series, substantial between-study heterogeneity, heterogeneous patient populations, insufficient disease classification, and variations in terms of outcome parameters as well as techniques. Furthermore, long-term data are limited.

CONCLUSION

This meta-analysis supports not only the benefits of permanent SNM for various nLUTDs but also high overall success rates, similar to idiopathic patients. Current data of the analyzed studies showed that SNM is safe for these patients. However, more vigorous studies and/or registries are needed before definitive conclusions can be drawn.

Effectiveness of percutaneous posterior tibial nerve stimulation for the management of bowel dysfunction in multiple sclerosis patients

BACKGROUND

Neurogenic bowel dysfunctions (NBDs) in the form of both fecal incontinence (FI) and functional constipation (FC) are frequent in multiple sclerosis (MS) patients and significantly affect their quality of life. Therapeutic options are limited.

OBJECTIVE

To investigate effectiveness of percutaneous posterior tibial nerve stimulation (PTNS) in MS patients suffering from FI and FC.

METHODS

Prevalence and severity of FI and FC were prospectively collected among MS patients undergoing 12 weeks of PTNS for neurogenic bladder. The Cleveland Clinic Fecal Incontinence Score (CCFIS) and the Rome III criteria were used to define FI and FC, respectively. Subjective treatment satisfaction was estimated using the Benefit Satisfaction and Willingness to Continue (BSWC) questionnaire.

RESULTS

A total of 60 patients undergoing PTNS suffered from NBDs (25 FI+/FC+, 5 FI+/FC-, 30 FI-/FC+). Median CCFIS decreased after PTNS from 12.0 (11.0-13.0) to 8.5 (7.0-11.0, p < 0.001), with particular improvements in liquid and flatal incontinence, pads' need, and lifestyle restrictions. Seven patients became FC free after PTNS and no patients developed FC during the study (p = 0.023). More than 50% of the patients were satisfied and willing to continue PTNS at study end.

CONCLUSION

PTNS represents a valid minimally invasive alternative treatment for MS patients suffering from NBDs.

Sacral neuromodulation to treat voiding dysfunction in patients with previous pelvic surgery for deep infiltrating endometriosis: our centre's experience

Introduction and hypothesis

Voiding symptoms/dysfunctions (VS/Ds) after surgery for deep-infiltrating endometriosis (DIE) are frequent (20% of patients) and, together with bowel dysfunctions, may represent a de novo disorder due to surgical damage of the pelvic plexus or a worsening of pre-existent functional damage. Sacral neuromodulation (SNM) might improve voiding symptoms by treating dysfunctional voiding. The aim of this study is to report our experience with SNM in patients treated with surgery for DIE.

Methods

We retrospectively enrolled 13 patients with VS/Ds after surgery for DIE. All patients were investigated with urodynamic studies (UDS) and agreed to undergo SNM. Pre-existing VS/Ds, bowel disorders and pelvic pain, DIE surgical procedures, UDS and SNM test results were recorded.

Results

After surgery for DIE, functional bladder outflow obstruction and detrusor acontractility were observed in nine and four patients, respectively. Chronic pelvic pain was present in seven cases. Twelve patients developed constipation, whilst one patient had de novo faecal incontinence. After the SNM testing period, nine patients (69.2%) experienced a significant improvement of symptoms that led to definitive implant. Four patients (30.8%) had no symptom relief and the system was removed.

Conclusions

Functional bladder outflow obstruction and urinary retention are the most common VS/Ds after surgery for DIE. SNM may be an effective option for these patients, probably due to its action in improving the dysfunctional voiding, which was likely to be already present as part of the “endometriotic syndrome” and got worse after pelvic surgery. Results for pelvic pain control and gastrointestinal disorders should not be underestimated.

Neural pathway of bellows response during SNM treatment revisited: Conclusive evidence for direct efferent motor response

BACKGROUND

In sacral neuromodulation (SNM) patients, it is thought the bellows response elicited upon sacral spinal nerve stimulation is reflex-mediated. Therefore the mechanism of action of SNM is considered to be at the spinal or supraspinal level. These ideas need to be challenged.

OBJECTIVE

To identify the neural pathway of the bellows response upon sacral spinal nerve stimulation.

DESIGN, SETTING, AND PARTICIPANTS

Single tertiary center, prospective study (December 2017-June 2019) including 29 patients with overactive bladder refractory to first-line treatment.

INTERVENTION

Recording of the pelvic floor muscle response (PFMR) using a camcorder and electromyography (EMG) (intravaginal probe and concentric needles) upon increasing stimulation during lead or implantable pulse generator placement.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The lowest stimulation intensity needed to elicit a visual PFMR and electrical PFMR was determined. Electrical PFMRs were subdivided according to their latency.

OUTCOME

the association between visual and electrical PFMRs. Statistical analyses were performed using the weighted kappa coefficient.

RESULTS

Three different electrical PFMRs could be identified by surface and needle EMG, corresponding with a direct efferent motor response (R1), oligosynaptic (R2), and polysynaptic (R3) afferent reflex response. Only the R1 electrical PFMR was perfectly associated with the visual PFMR (κ = 0.900).

CONCLUSIONS

The visual PFMRs upon sacral spinal nerve stimulation are direct efferent motor responses. A reopening of the discussion on the mechanism of action of SNM is possibly justified.