Programming Algorithms for Sacral Neuromodulation: Clinical Practice and Evidence-Recommendations for Day-to-Day Practice

[Invasive neurostimulation in neuro-urology: state of the art]

Modulation or stimulation of the nerves supplying the lower urinary tract is a possible treatment option for dysfunction of the lower urinary tract, pelvic floor and rectum if conservative or minimally invasive treatment approaches fail. This overview shows the possibilities and limitations of sacral neuromodulation, sacral deafferentation with sacral anterior root stimulation and conus deafferentation.Sacral neuromodulation (SNM) is a procedure for the treatment of refractory pelvic floor dysfunction of various origins (idiopathic, neurogenic or post-operative), such as overactive bladder, non-obstructive retention and faecal incontinence. A particular advantage of SNM is the possibility of prior test stimulation with a high prognostic value. The procedure is minimally invasive, reversible and associated with relatively low morbidity rates.Following the introduction of MRI-compatible SNM systems, there has been renewed interest in the treatment of neurogenic bladder dysfunction. A recent meta-analysis reports similar success rates as in the idiopathic patient population.Sacral deafferentation with implantation of a sacral anterior root stimulator (SARS/SDAF) is an excellent therapeutic option for patients with spinal cord injury, which can significantly improve the quality of life of those affected and, in addition to treating neurogenic lower urinary tract dysfunction, can also have a positive effect on neurogenic bowel dysfunction, neurogenic sexual dysfunction or autonomic dysreflexia. If conservative or minimally invasive treatment fails, it is crucial for the success of this procedure to consider SDAF/SARS at an early stage in order to avoid irreversible organic damage.Conus deafferentation (KDAF) is a less invasive surgical treatment option for patients with spinal cord injury for whom sacral deafferentation would be indicated but who would not benefit from the simultaneous implantation of a sacral anterior root stimulator. In principle, these patients also have the option of being subsequently treated with an extradural implant and thus utilising the advantages of anterior root stimulation. Indications for KDAF are autonomic dysreflexia, therapy-refractory detrusor overactivity, recurrent urinary tract infections, urinary incontinence and spasticity triggered by detrusor overactivity. With KDAF, we have a safe and efficient procedure with great potential for improving the spectrum of paraplegiological and neuro-urological treatment.

Sensing in Sacral Neuromodulation: A Feasibility Study in Subjects With Urinary Incontinence and Retention

OBJECTIVES

Sacral neuromodulation (SNM) therapy standard of care relies on visual-motor responses and patient-reported sensory responses in deciding optimized lead placement and programming. Automatic detection of stimulation responses could offer a simple, consistent indicator for optimizing SNM. The purpose of this study was to measure and characterize sacral evoked responses (SERs) resulting from sacral nerve stimulation using a commercial, tined SNM lead.

MATERIALS AND METHODS

A custom external research system with stimulation and sensing hardware was connected to the percutaneous extension of an implanted lead during a staged (tined lead) evaluation for SNM. The system collected SER recordings across a range of prespecified stimulation settings (electrode configuration combinations for bipolar stimulation and bipolar sensing) during intraoperative and postoperative sessions in 21 subjects with overactive bladder (OAB) and nonobstructive urinary retention (NOUR). Motor and sensory thresholds were collected during the same sessions.

RESULTS

SERs were detected in all 21 subjects. SER morphology (number of peaks, magnitude, and timing) varied across electrode configurations within and across subjects. Among subjects and electrode configurations tested, recordings contained SERs at motor threshold and/or sensory threshold in 75% to 80% of subjects.

CONCLUSIONS

This study confirmed that implanted SNM leads can be used to directly record SERs elicited by stimulation in subjects with OAB and NOUR. SERs were readily detectable at typical SNM stimulation settings and procedural time points. Using these SERs as possible objective measures of SNM response has the capability to automate patient-specific SNM therapy, potentially providing consistent lead placement, programming, and/or closed-loop therapy.

Anti-Inflammatory Effects of Two-Week Sacral Nerve Stimulation Therapy in Patients With Ulcerative Colitis

BACKGROUND AND AIMS

Sacral nerve stimulation (SNS) showed anti-inflammatory properties in animal models of inflammatory bowel disease. We aimed to evaluate the effectiveness and safety of SNS in patients with ulcerative colitis (UC).

MATERIALS AND METHODS

Twenty-six patients with mild and moderate disease were randomized into two groups: SNS (delivered at S3 and S4 sacral foramina) and sham-SNS (delivered 8-10 mm away from sacral foramina), with the therapy applied once daily for one hour, for two weeks. We evaluated the Mayo score and several exploratory biomarkers, including C-reactive protein in the plasma, pro-inflammatory cytokines and norepinephrine in the serum, assessment of autonomic activity, and diversity and abundance of fecal microbiota species.

RESULTS

After two weeks, 73% of the subjects in the SNS group achieved clinical response, compared with 27% in the sham-SNS group. Levels of C-reactive protein, pro-inflammatory cytokines in the serum, and autonomic activity were significantly improved toward a healthy profile in the SNS group but not in the sham-SNS group. Absolute abundance of fecal microbiota species and one of the metabolic pathways were changed in the SNS group but not in the sham-SNS group. Significant correlations were observed between pro-inflammatory cytokines and norepinephrine in the serum on the one side and fecal microbiota phyla on the other side.

CONCLUSIONS

Patients with mild and moderate UC were responsive to a two-week SNS therapy. After performing further studies to evaluate its efficacy and safety, temporary SNS delivered through acupuncture needles may become a useful screening tool for identifying SNS therapy responders before considering long-term implantation of the implantable pulse generator and SNS leads for performing long-term SNS therapy.

Pathways and parameters of sacral neuromodulation in rats

The stimulation paradigm for sacral neuromodulation has remained largely unchanged since its inception. We sought to determine, in rats, whether stimulation-induced increases in bladder capacity correlated with the proportion of sensory pudendal (PudS) neurons at each stimulated location (L6, S1). If supported, this finding could guide the choice of stimulation side (left/right) and level (S2, S3, S4) in humans. Unexpectedly, we observed that acute stimulation at clinically relevant (low) amplitudes [1-1.5 × motor threshold (Tm)], did not increase bladder capacity, regardless of stimulus location (L6 or S1). More importantly for the ability to test our hypothesis, there was little anatomic variation, and S1 infrequently contributed nerve fibers to the PudS nerve. During mapping studies we noticed that large increases in PudS nerve activation occurred at amplitudes exceeding 2Tm. Thus, additional cystometric studies were conducted, this time with stimulation of the L6-S1 trunk, to examine further the relationship between stimulation amplitude and cystometric parameters. Stimulation at 1Tm to 6Tm evoked increases in bladder capacity and decreases in voiding efficiency that mirrored those produced by PudS nerve stimulation. Many animal studies involving electrical stimulation of nerves of the lower urinary tract use stimulation amplitudes that exceed those used clinically (∼1Tm). Our results confirm that high amplitudes generate immediate changes in cystometric parameters; however, the relationship to low-amplitude chronic stimulation in humans remains unclear. Additional studies are needed to understand changes that occur with chronic stimulation, how these changes relate to therapeutic outcomes, and the contribution of specific nerve fibers to these changes.NEW & NOTEWORTHY Acute low-amplitude electrical stimulation of sacral nerve (sacral neuromodulation) did not increase bladder capacity in anesthetized CD, obese-prone, or obese-resistant rats. Increasing stimulation amplitude correlated with increases in bladder capacity and pudendal sensory nerve recruitment. It is unclear how the high-amplitude acute stimulation that is commonly used in animal experiments to generate immediate effects compares mechanistically to the chronic low-amplitude stimulation used clinically.

[Sacral Neuromodulation for Fecal Incontinence and Constipation: Evidence, Programming and Long-term Management]

BACKGROUND

Over the last two decades, sacral neuromodulation (SNM) has established its role in the treatment of functional pelvic organ-/pelvic floor disorders. Even though the mode of action is not fully understood, SNM has become the preferred surgical treatment of fecal incontinence.

METHODS AND RESULTS

A literature search was carried out on programming sacral neuromodulation and long-term outcomes in treating fecal incontinence and constipation.Sacral neuromodulation was found to be successful in the long term. Over the years, the spectrum of indications has expanded, and now includes patients presenting with anal sphincter lesions. The use of SNM for low anterior resection syndrome (LARS) is currently under clinical investigation. Findings of SNM for constipation are less convincing. In several randomised crossover studies, no success was demonstrated, even though it is possible that subgroups may benefit from the treatment. Currently the application cannot be recommended in general.The pulse generator programming sets the electrode configuration, amplitude, pulse frequency and pulse width. Usually pulse frequency and pulse width follow a default setting (14 Hz, 210 s), while electrode configuration and stimulation amplitude are adjusted individually to the patient need and perception of stimulation.Despite low infection rates and few electrode-/pulse generator dysfunctions, up to 65% of patients require surgical reintervention during long term follow-up - in 50% of cases because of battery depletion, which is an expected event. At least one reprogramming is necessary in about 75% of the patients during the course of the treatment, mostly because of changes in effectiveness, but rarely because of pain. Regular follow-up visits appear to be advisable.

CONCLUSION

Sacral neuromodulation can be considered to be a safe and effective long-term therapy of fecal incontinence. To optimise the therapeutic effect, a structured follow-up regime is advisable.

Electroceuticals for Neurogastroenterology and Motility Disorders

PURPOSE OF REVIEW

To provide an updated overview on use of electrostimulation in gastrointestinal motility disorders and obesity, with a focus on gastric electrical stimulation, vagal nerve stimulation and sacral nerve stimulation.

RECENT FINDINGS

Recent studies on gastric electrical stimulation for chronic vomiting showed a decrease in frequency of vomiting, but without significant improvement in quality of life. Percutaneous vagal nerve stimulation shows some promise for both symptoms of gastroparesis and IBS. Sacral nerve stimulation does not appear effective for constipation. Studies of electroceuticals for treatment of obesity have quite varied results with less clinical penetrance of the technology. Results of studies on the efficacy of electroceuticals have been variable depending on pathology but this area remains promising. Improved mechanistic understanding, technology and more controlled trials will be helpful to establish a clearer role for electrostimulation in treatment of various GI disorders.

Faecal incontinence is associated with an impaired rectosigmoid brake and improved by sacral neuromodulation

BACKGROUND

The rectosigmoid brake, characterised by retrograde cyclic motor patterns on high-resolution colonic manometry, has been postulated as a contributor to the maintenance of bowel continence. Sacral neuromodulation (SNM) is an effective therapy for faecal incontinence, but its mechanism of action is unclear. This study aims to investigate the colonic motility patterns in the distal colon of patients with faecal incontinence, and how these are modulated by SNM.

METHODS

A high-resolution fibreoptic colonic manometry catheter, containing 36 sensors spaced at 1-cm intervals, was positioned in patients with faecal incontinence undergoing stage 1 SNM. One hour of pre- and post meal recordings were obtained followed by pre- and post meal recordings with suprasensory SNM. A 700-kcal meal was given. Data were analysed to identify propagating contractions.

RESULTS

Fifteen patients with faecal incontinence were analysed. Patients had an abnormal meal response (fewer retrograde propagating contractions compared to controls; p = 0.027) and failed to show a post meal increase in propagating contractions (mean 17 ± 6/h premeal vs. 22 ± 9/h post meal, p = 0.438). Compared to baseline, SNM significantly increased the number of retrograde propagating contractions in the distal colon (8 ± 3/h premeal vs. 14 ± 3/h premeal with SNM, p = 0.028). Consuming a meal did not further increase the number of propagating contractions beyond the baseline upregulating effect of SNM.

CONCLUSION

The rectosigmoid brake was suppressed in this cohort of patients with faecal incontinence. SNM may exert a therapeutic effect by modulating this rectosigmoid brake.

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.

Sacral Neuromodulation with the InterStim System for Overactive Bladder: 3-Year Results from the French Prospective, Multicenter, Observational SOUNDS Study

BACKGROUND

SOUNDS strengthens the evidence basis of sacral neuromodulation (SNM) for overactive bladder (OAB) through real-world data.

OBJECTIVE

To analyze diary-based effectiveness, quality of life (QoL), disease severity, symptom bother, and safety data for SNM with the InterStim system up to 3 yr after implantation.

DESIGN, SETTING, AND PARTICIPANTS

Twenty-five representative French sites enrolled 291 patients with OAB followed according to the local standard of care. Overall, 229 patients received a de novo or replacement InterStim implant and had four follow-up visits, two within the first yr and annually thereafter. A total of 190 patients completed the fourth follow-up visit after a mean of 33.7 ± 3.7 mo.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The effectiveness outcomes measured were changes in daily voids and leaks and the therapy responder rates. Other outcomes included validated QoL data (Ditrovie and EuroQol 5-dimension 5-level questionnaires), disease severity (Urinary Symptom Profile [USP]), symptom bother rated using a numeric rating scale (NRS), and safety data. Follow-up data were compared to baseline results using the Wilcoxon signed-rank test.

RESULTS AND LIMITATIONS

Average daily voids and leaks were significantly reduced at all time points up to 3 yr after implantation (p < 0.05) except for voids at 21 mo in the group receiving a replacement device. The therapeutic response for urinary urge incontinence at the fourth follow-up was 72% for the de novo group and 86% for the replacement group. Disease-specific QoL (Ditrovie), OAB-specific symptom severity (USP domain 2), and NRS-rated disease bother were significantly improved at all visits (p < 0.001). Device- or procedure-related adverse events occurred in 49% of patients, with 68% of the events classified as minor (Clavien-Dindo grade I or II). Surgical revisions were performed in 33% of patients, including permanent removal in 13%, over a mean exposure time of 44.4 ± 15.3 mo.

CONCLUSIONS

This study confirms the safety and effectiveness of SNM for OAB and improvements in QoL and disease bother in real life.

PATIENT SUMMARY

Our study in French patients with overactive bladder showed that disease symptoms and bother were significantly reduced and quality of life was significantly improved over a study duration of approximately 3 yr after implantation of a device to stimulate nerves that control the bladder. This trial is registered at ClinicalTrials.gov as NCT02186041.

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.

Closed-loop sacral neuromodulation for bladder function using dorsal root ganglia sensory feedback in an anesthetized feline model

Overactive bladder patients suffer from a frequent, uncontrollable urge to urinate, which can lead to a poor quality of life. We aim to improve open-loop sacral neuromodulation therapy by developing a conditional stimulation paradigm using neural recordings from dorsal root ganglia (DRG) as sensory feedback. Experiments were performed in 5 anesthetized felines. We implemented a Kalman filter-based algorithm to estimate the bladder pressure in real-time using sacral-level DRG neural recordings and initiated sacral root electrical stimulation when the algorithm detected an increase in bladder pressure. Closed-loop neuromodulation was performed during continuous cystometry and compared to bladder fills with continuous and no stimulation. Overall, closed-loop stimulation increased bladder capacity by 13.8% over no stimulation (p < 0.001) and reduced stimulation time versus continuous stimulation by 57.7%. High-confidence bladder single units had a reduced sensitivity during stimulation, with lower linear trendline fits and higher pressure thresholds for firing observed during stimulation trials. This study demonstrates the utility of decoding bladder pressure from neural activity for closed-loop control of sacral neuromodulation. An underlying mechanism for sacral neuromodulation may be a reduction in bladder sensory neuron activity during stimulation. Real-time validation during behavioral studies is necessary prior to clinical translation of closed-loop sacral neuromodulation.

The Influence of Electrode Configuration Changes on the Sensory and Motor Response During (Re)Programming in Sacral Neuromodulation

OBJECTIVES

This study aimed to assess the neurophysiological basis behind troubleshooting in sacral neuromodulation (SNM). Close follow-up of SNM patients with program parameter optimization has proven to be paramount by restoring clinical efficacy and avoiding surgical revision.

MATERIALS AND METHODS

A total of 34 successful SNM patients (28 overactive bladder wet, six nonobstructive urinary retention) with an implantable pulse generator were included. All possible bipolar and monopolar electrode settings were tested at sensory threshold (ST) to evaluate sensory (mapped on a perineal grid with 1 cm² coordinates) and motor (peak-to-peak amplitude and latency of muscle action potential) responses of the pelvic floor. Pelvic floor muscle electromyography was recorded using a multiple array probe, placed intravaginally. Parametric tests were used for paired data: repeated-measures ANOVA or t-test. A nonparametric test was used for paired data: Friedman ANOVA or Wilcoxon signed rank (WSR) test; p < 0.05 was considered statistically significant. If significant, ANOVA was followed by Dunn-Bonferroni post hoc analysis.

RESULTS

Monopolar configurations showed significantly lower STs-1.38 ± 0.73 V vs 1.76 ± 0.89 V (paired t-test: p < 0.0001)-and presented with significantly higher peak-to-peak amplitudes-115.67 ± 79.03 μV vs 90.77 ± 80.55 μV (WSR: p = 0.005)-than bipolar configurations. When polarity was swapped, configurations with the cathode distal to the anode showed significantly lower STs, 1.73 ± 0.91 V vs 1.85 ± 0.87 V (paired t-test: p = 0.003), and mean peak-to-peak amplitudes, 81.32 ± 72.82 μV vs 100.21 ± 90.22 μV (WSR: p = 0.0001). Cathodal changes resulted in more changes in sensory responses than anodal changes (χ² test: p = 0.044). In cathodal changes only, peak-to-peak amplitudes were significantly higher when the distance between electrodes was maximally spread (WSR: p = 0.046).

CONCLUSIONS

From a neurophysiological point of view, monopolar configurations stimulated more motor nerve fibers at lower STs, therefore providing more therapeutic efficiency. Swapping polarity or changing the position of the cathode led to different sensory and motor responses, serving as potential reprogramming options.

Reprogramming Sacral Neuromodulation for Sub-Optimal Outcomes: Evidence and Recommendations for Clinical Practice

Objectives

In some patients treated for urinary or fecal incontinence with sacral neuromodulation (SNM) persistence of symptoms, a reduction in efficacy or adverse effects of stimulation can occur. In such situations, further programming of the SNM device can help resolve problems. Infrequently hardware failure is detected. This article aims to provide practical guidance to solve sub‐optimal outcomes (troubleshooting) occurring in the course of SNM therapy.

Materials and Methods

A systematic literature review was performed. Collective clinical experience from an expert multidisciplinary group was used to form opinion where evidence was lacking.

Results

Circumstances in which reprogramming is required are described. Actions to undertake include changes of electrode configuration, stimulation amplitude, pulse frequency, and pulse width. Guidance in case of loss of efficacy and adverse effects of stimulation, developed by a group of European experts, is presented. In addition, various hardware failure scenarios and their management are described.

Conclusions

Reprogramming aims to further improve patient symptoms or ensure a comfortable delivery of the therapy. Initial changes of electrode configuration and adjustment of stimulation parameters can be performed at home to avoid unnecessary hospital visits. A logical and stepwise approach to reprogramming can improve the outcome of therapy and restore patient satisfaction.

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.

A prospective, multicenter, international study to explore the effect of three different amplitude settings in female subjects with urinary urge incontinence receiving interstim therapy

Aims

The aim of this study is to evaluate the effect of sub‐sensory amplitude settings of sacral neuromodulation therapy on overactive bladder symptoms in subjects with urinary urge incontinence.

Methods

Subjects who qualified for a neurostimulator device implant were randomized to one of three amplitude settings (50% of sensory threshold [ST], 80% of ST, and ST). Subjects completed urinary voiding diaries (3‐day), International consultation on incontinence modular questionnaire—overactive bladder symptoms quality of life questionnaire, and patient global impression of improvement (PGI‐I) to assess change in voiding symptoms and quality of life (QoL) from baseline through 12 weeks.

Results

Forty‐eight subjects had a successful test stimulation, 46 were implanted with a neurostimulator device and 43 completed the 12‐week follow‐up visit. The change from baseline to 12 weeks is −3.0 urinary incontinence (UI) episodes/day (95% confidence interval [CI]: −4.4 to −1.7) for the 50% of sensory threshold group, −2.9 UI episodes/day (95% CI: −4.7 to −1.2) for 80% of sensory threshold group, and −3.6 UI episodes/day (95% CI: −5.2 to −1.9) for the sensory threshold group. In each randomized group, improvements were observed in health‐related QoL, its subscales, and symptom interference. Subjects across all three randomization groups reported on the PGI‐I that their bladder condition was better at 12 weeks compared to before they were treated with InterStim therapy.

Conclusion

These findings provide insights into possible advancements in the postimplantation phase of therapy with potential for improved patient comfort and increased device longevity.

The role of pulse width manipulation compared to program changes alone for unsatisfactory sacral neuromodulation therapy: A retrospective matched-cohort analysis

AIM

Pulse width (PW) influences neuromodulation by its impact on nerve fiber recruitment. A paucity of data regarding the manipulation of PW in sacral neuromodulation (SNM) exists. This study describes the clinical features and outcomes of PW manipulation for unsatisfactory SNM therapy.

METHODS

A retrospective, single-institution review was performed of reprogrammed SNM patients between 2010 and 2019. Two cohorts were created: those with PW changes ± program changes and age-matched controls with program changes alone. Patients lacking follow-up and non-InterStim II models were excluded.

RESULTS

Out of 710 SNM interrogations, 147 (20.7%) had PW changes and 80 met inclusion criteria. Most PW changes were shortened (61/80, 76.3%). Clinical features did not differ between cohorts except by indication for reprogramming. The most common indication for PW change was painful stimulation (34/80, 43%), whereas in controls it was suboptimal efficacy (76/80, 95%). Clinical success was stratified by indication. There was a higher improvement in efficacy in the PW cohort (61%, 17/28 vs. 36%, 27/76, p = .02). PW manipulation successfully relieved painful stimulation in 50% (17/34 vs. 0/3, p = .23), which was more likely with a shortened compared to extended PW (14/15, 93.3% vs. 0/6, 0%, p < .01). PW resulted in improvement in localization of the stimulus in 94% (17/18 vs. 0/1, p = .10). The subsequent lead revision or explant was significantly higher in the PW cohort (43% vs. 25%, p = .03).

CONCLUSION

PW manipulation may aid the salvage of unsatisfactory SNM therapy. These findings represent an initial assessment of the role of PW in SNM, particularly regarding the efficacy and painful stimuli. The further prospective investigation is warranted.