International Continence Society best practice statement for use of sacral neuromodulation

Revision Rates for Rechargeable Versus Non-Rechargeable Sacral Neuromodulation Devices in the Management of Overactive Bladder

PURPOSE

Overactive bladder (OAB) is a prevalent condition that can have a significant impact on quality of life. Sacral neuromodulation (SNM) is proven as an effective treatment option for OAB patients. Rechargeable devices have gained popularity in recent years. However, there is a paucity of data investigating revision rates for rechargeable SNM devices and associated impacting factors.

MATERIALS AND METHODS

We conducted a retrospective cohort study to investigate the revision rates of SNM devices in patients diagnosed with OAB. Patients who underwent implantation of rechargeable or non-rechargeable SNM devices at our institution between January 2019 and June 2023 were included. Revision events, reasons for revisions, and patient demographics were analyzed and compared between the device groups.

RESULTS

The study included 246 patients. One hundred fifty received rechargeable SNM devices and 96 received non-rechargeable devices. Revision rates were significantly different between the two groups, with 34% of patients in the rechargeable device group requiring revisions compared to 13.5% in the non-rechargeable group (p < 0.001). The most common reasons for revision in the rechargeable group included difficulty charging (35.3%) and reduction of symptom improvement (23.5%). Having a rechargeable device resulted in a significantly higher probability of requiring a revision over time compared to non-rechargeable (p < 0.001).

CONCLUSION

Our study demonstrated that patients who received rechargeable SNM devices were more likely to require revision. Factors such as device malfunction or difficulties connecting to the device may contribute to the higher revision rates. Further studies are needed to elucidate factors affecting revision rates in SNM devices.

A prospective feasibility study to differentiate sacral neuromodulation lead electrode configurations using motor and sensory thresholds and locations of sensation

BACKGROUND

Accurate positioning and programming of sacral neuromodulation (SNM) relies upon the use of several intraoperative and postoperative stimulation measurements. While the clinical utility of these acute measurements including pelvic floor motor thresholds (PFMT), toe/leg motor thresholds (TMT), and sensory thresholds (ST), are widely accepted, their usefulness in quantitative research remains unclear. The purpose of this prospective study was to test these measurements and gauge their utility in future research.

METHODS

Eight participants received Axonics SNM, 6 Medtronic Interstim II, and 2 Medtronic Micro SNM. PFMT was measured after implantation. ST and the location of sensation (LOS) were measured immediately postoperatively (PO), at pre-release from the surgery center (PR), and during a follow-up clinic visit (FU). Thresholds were compared across contact and time using linear mixed-effects models.

RESULTS

Significant differences in PFMT were found across electrode configurations, with stimulation through proximal contacts exhibiting lower PFMT than distal configurations. ST displayed no significant differences across electrodes and showed minimal changes over time. LOS exhibited substantial variability across patients and periods.

CONCLUSIONS

Results suggest that PFMT were able to differentiate differences across electrode configurations that may be useful for future quantitative research. The lack of differences in ST and LOS across electrode configurations was interesting given the focus on these measurements clinically. Future testing is to confirm these limitations.

Supplemental Lidocaine Patches Prior to Percutaneous Nerve Evaluation, a Randomized Trial

IMPORTANCE

Improving patient comfort during percutaneous nerve evaluation (PNE), a trial procedure for sacral neuromodulation, is essential.

OBJECTIVE

The aim of the study was to determine whether the use of a lidocaine patch (LP) prior to PNE procedure improves the pain associated with PNE.

STUDY DESIGN

This double-masked, randomized controlled trial compared a 4% LP to placebo patch (PP) immediately prior to PNE. Female patients ≥18 years of age were included if they were undergoing an office PNE, performed bilaterally and without fluoroscopy, for any indication. Either a lidocaine or placebo patch was placed over the sacrum 30 minutes prior to PNE. Additional local anesthesia with 2% lidocaine without epinephrine was administered per surgeon discretion. All patients received some volume of injectable lidocaine with their procedures. Secondary outcomes included volume of injectable lidocaine used, progression to a permanent implant, amplitude of perineal sensation, and patient satisfaction.

RESULTS

Thirty-nine women were enrolled, with 20 receiving LP and 19 patients receiving PP. Lower 100-mm visual analog scale pain score was seen in the LP group (45 ± 17 with LP vs 61 ± 21 with PP, P = 0.018). This difference was statistically and clinically significantly different between groups. The total injectable lidocaine, patient satisfaction, and progression to permanent implant were similar between groups.

CONCLUSIONS

Patients experienced clinically and statistically significantly less pain at the time of PNE with a preprocedural LP when compared to placebo, despite similar use of local anesthetic. Satisfaction rates were high among all patients.

Acute Cortical Brain Neuroexcitation Can Be Detected With Sacral Neuromodulation

INTRODUCTION

Functional near infrared spectroscopy (fNIRS) is a noninvasive technique for measuring cortical brain neuroexcitation.

OBJECTIVE

The objective of this study was to determine if fNIRS could detect differences in prefrontal cortex (PFC) neuroexcitation due to acute ON/OFF changes in sacral neuromodulation (SNM) during natural bladder filling.

STUDY DESIGN

Female participants who had an SNM device implanted for ≥6 months underwent a 2-fill natural hydration protocol in this cross-sectional study. Continuous oxygenated hemoglobin (O2Hb) concentration was recorded using an fNIRS headcap as a measure of neuroexcitation. Sacral neuromodulation devices were acutely changed from ON to OFF and OFF to ON in 3-minute cycles. One-minute segments of fNIRS signals before and after acute modulation were selected and linear fitting was used to output slope. Two-minute control periods at a similar level of bladder sensation were used for comparison.

RESULTS

Twelve women completed the study and median time from SNM implant was 13 (6, 42) months. In the left and middle PFC regions, there was a significant alteration of fNIRS slope (∆O2Hb/time) from baseline to postactivation (OFF to ON) compared to control periods. The first deactivation (ON to OFF) showed continuation of the prior fNIRS slope. The control segments showed stability of averaged O2Hb signals regardless of sensation in all brain regions.

CONCLUSIONS

This study indicates that fNIRS may be a useful tool to assess acute changes in neuroexcitation of the PFC in response to SNM device activation in female patients with overactive bladder. The results suggest that SNM may acutely affect the PFC during bladder filling.

Development of a Predictive Tool for Midterm Success of Sacral Neuromodulation in Non-Neurogenic Overactive Bladder Syndrome

OBJECTIVES

To identify factors that can predict both test phase and midterm success of sacral neuromodulation (SNM) in refractory non-neurogenic overactive bladder syndrome (nnOAB) based on preoperative clinical and urodynamic data.

MATERIALS AND METHODS

We conducted a two-center retrospective study and included all individuals with nnOAB who underwent a test phase between 2005 and 2021, with or without subsequent implantation of an SNM device. Only those with preoperative urodynamic assessment data were included. SNM success was defined as≥ $\ge $  50% improvement in one of the bladder diary parameters, associated with≥ $\ge $  50% symptom improvement. Individuals underwent follow-up evaluation at 2 years.

RESULTS

In total, 191 individuals were included (163 women), 69% of whom underwent SNM device implantation. At the preoperative urodynamic exam, 115 individuals had detrusor overactivity (DO). Test phase success was associated with younger age (p = 0.009). 24-month SNM success was associated with lower maximal detrusor pressure at DO (Pdet max DO) at baseline (p = 0.045). Other predictive factors for success at 2 years were female (p = 0.03), a history of stress incontinence surgery (p = 0.01), a low maximum urethral closure pressure (MUCP) (p = 0.04), a low volume at first DO (VFDO) (p = 0.03), and a high maximum cystometric capacity (MCC) (p = 0.03). We developed a tool to predict success at 2 years. The following threshold values were significantly associated with treatment success: MUCP < 58 cmH2O, VFDO < 170 mL, and MCC > 254 mL.

CONCLUSION

Age predicted test phase success. Pdet max DO, gender, history of incontinence surgery, high MUCP, MCC, and VFDO predicted midterm success of SNM in people with nnOAB.

A Deep Analysis of the Pelvic Floor Motor Response in Sacral Neuromodulation Linking It to Outcome

OBJECTIVES

This study aimed to characterize the pelvic floor muscles (PFM) motor response provoked during sacral neuromodulation (SNM) programming, determining its utility in improving therapy delivery.

MATERIALS AND METHODS

This prospective study (January 2018-September 2021) included patients with overactive bladder (OAB) or nonobstructive urinary retention (NOUR) who underwent unilateral SNM. An external pulse generator was connected for three weeks. Success was defined as ≥50% improvement. Sensory threshold (ST), motor threshold (MT), and their ratio (MT-ST) were analyzed. PFM electromyography was recorded using a multiple array probe. A linear regression model with ST, MT, MT-ST, and mean natural log transformation (peak-to peak-amplitude) vs outcome (percentage improvement) was performed. Differences in electrical PFM motor response amplitude between different electrical stimulation levels (ST ± 0.5 mA) and different parts (four sides, three depths) of the pelvic floor were modeled using linear mixed model analysis (LMM).

RESULTS

The study population comprised 64 women (overall success 80%). Responders presented with significantly lower MT and MT-ST (unpaired t-test: p = 0.0271 and p = 0.0158, respectively). MT and MT-ST proved a significant relationship with percentage improvement (linear regression [lin. Regr.] p = 0.0304, R2 = 0.0745 and lin. Regr. p = 0.0107, R2 = 0.1020, respectively). PFM amplitude showed a significant relationship with percentage improvement for all stimulation amplitudes (ST ± 0.5 mA) (lin. Regr. p < 0.0001, R2 = 0.2560), and subsensory stimulation intensities (lin. Regr. p = 0.0008, R2 = 0.1673). Responders presented with a different evolution in increase in overall peak-to-peak amplitude over increased stimulation intensities (LMM: p = 0.0160), presenting with a significantly higher slope. This was significantly different depending on the percentage improvement for all the different sides and depths, with contralateral superior being the only exception (LMM: p = 0.0071, range: 0.0663-<0.0001).

CONCLUSIONS

A clear correlation was found between therapy efficacy and PFM motor response elicited by unilateral sacral spinal nerve stimulation, linking lead placement and SNM outcome. Responders presented with lower MTs, lower MT-STs, higher compound muscle action potentials, and higher continuous activation of their PFM at subsensory stimulation levels than did nonresponders.

Predicting success using response after lead implantation with sacral neuromodulation for urgency incontinence

IMPORTANCE

Many women report inadequate symptom control after sacral neuromodulation (SNM), despite 50% reduction in urgency incontinence episodes (UUIE) after test stimulation.

OBJECTIVE

To determine the ideal percent UUIE reduction after test stimulation that predicts 24-month success.

STUDY DESIGN

Using data from a multicenter SNM trial, we constructed receiver operating characteristic curves to identify an ideal threshold of percent UUIE reduction after test stimulation. We defined 24-month success as Patient Global Impression of Improvement of "very much better" to "better." We compared predictive accuracy of two models predicting success: (1) percent UUIE reduction alone and (2) with baseline characteristics.

RESULTS

Of 149 women (median [IQR] baseline daily UUIE 4.7 [3.7, 6.0]), the ideal threshold for 24-month success was 72% (95% confidence interval 64,76%) UUIE reduction with accuracy 0.54 (0.42, 0.66), sensitivity 0.71 (0.56, 0.86) and specificity 0.27 (0.05, 0.55). The accuracy of the 50% reduction threshold was 0.60 (0.49, 0.71), sensitivity 0.95 (0.88, 1.0) and specificity 0.04 (0.0, 0.12). Percent reduction in UUIE was not better than chance in predicting 24-month success (concordance index [c-index] 0.47 [0.46, 0.62]); adding age, body mass index, diabetes mellitus and visual or hearing impairment the c-index was 0.68 (0.61, 0.78).

CONCLUSIONS

Among women who received an internal pulse generator (IPG) due to ≥50% UUIE reduction after test stimulation, we found no ideal threshold that better predicted 24-month success. Percent reduction in UUIE after test stimulation poorly predicts 24-month success with or without clinical factors. Given this, re-evaluating how we determine who should receive an IPG is needed.

A Prospective Feasibility Study to Differentiate Sacral Neuromodulation Lead Electrode Configurations Using Motor and Sensory Thresholds and Locations of Sensation

Background

Accurate positioning and effective programming of sacral neuromodulation (SNM) relies upon the use of several acute stimulation measurements. While the clinical utility of these acute measurements including pelvic floor motor thresholds (PFMT), toe/leg motor thresholds (TMT), and sensory thresholds (ST), are widely accepted, their usefulness in quantitative research remains unclear. The purpose of this prospective study was to test these measurements and gauge their utility in future research.

Methods

Eight participants received Axonics SNM, 6 Medtronic Interstim II, and 2 Medtronic Micro SNM. PFMT was measured after implantation. ST and the location of sensation (LOS) were measured immediately postoperatively (PO), at pre-release from the surgery center (PR), and during a follow-up clinic visit (FU). Thresholds were compared across contact and time using linear mixed-effects models.

Results

Significant differences in PFMT were found across electrode configurations, with stimulation through proximal contacts exhibiting lower PFMT than distal configurations. ST displayed no significant differences across electrodes and showed minimal changes over time. LOS exhibited substantial variability across patients and periods.

Conclusions

Results suggest that PFMT were able to differentiate differences across electrode configurations that may be useful for future quantitative research. The lack of differences in ST and LOS across electrode configurations was interesting given the focus on these measurements clinically. Future testing is to confirm these limitations.

Gastric and sacral electrical stimulation for motility disorders-A clinical perspective

BACKGROUND

Electrical stimulation of the gut has been investigated in recent decades with a view to treating various gastro-intestinal motility disorders including, among others, gastric electrical stimulation to relieve nausea and vomiting associated with gastroparesis and sacral neuromodulation to treat fecal incontinence and/or constipation. Although their symptomatic efficacy has been ascertained by randomized controlled trials, their mechanisms of action are not fully understood.

PURPOSE

This review summarizes the past year's literature on the mechanisms of action of gut electrical stimulation therapies, including their impact on the gut-brain axis.

Can we predict whether a man with acute or chronic urinary retention will void after bladder outflow resistance reduction surgery? ICI-RS 2023

AIMS

To address the predictive factors of a successful voiding after bladder outflow resistance reduction surgery (BORRS) in men presenting with acute or chronic urinary retention (UR).

METHODS

A think tank (TT) of ICI-RS was gathered in 2023, Bristol, UK, to discuss several aspects of the problem, such as the pathophysiology of UR, the clinical and urodynamic evaluation of men with UR and whether it is possible to predict which men will be able to successfully void after treatment with contemporary surgical options.

RESULTS

The TT agreed that successful voiding after BORRS depends on several factors but that a strong recommendation cannot be made regarding preoperative evaluation and whether there are predictive factors of success because of the heterogeneity of patients and methodology in published trials. The diagnosis of obstruction in men with UR may be challenging when there is apparent reduced detrusor contraction during urodynamic studies. Even in the absence of bladder contractility there is documentation of such cases that have voided adequately after BORRS. Still, detrusor underactivity and inadequate relief of prostatic obstruction are the main causes of an unsuccessful voiding after BORRS. Conventional resection and enucleation methods remain the most successful surgeries in relieving UR in men, whereas the efficacy of minimally invasive surgical treatments needs to be assessed further.

CONCLUSION

Research is needed to understand the pathophysiology of UR and the predictors of successful voiding after different types of BORRS in men with UR.

Could a better understanding of the underlying pathophysiologies lead to more informed treatment choices in patients with lower urinary tract dysfunction due to an acontractile or underactive detrusor? ICI-RS 2023

INTRODUCTION

The underlying pathophysiology behind a diagnosis of acontractile or underactive detrusor at invasive urodynamics is very heterogeneous. Lack of etiological classification currently limits the possibility of stratifying therapy.

METHODS

This subject was discussed at a think-tank on the subject at the International Consultation on Incontinence-Research Society held in Bristol, June 2023. This manuscript is a result of those deliberations and the subsequent discussions of the think-tank.

RESULTS

There are challenges in defining abnormalities of detrusor contraction with resultant implications for available evidence. Pathology at any level of the neuromuscular pathway can impair or prevent a detrusor voiding contraction. Attempts have been made to identify clinical markers that might predict an underactive detrusor but strong supporting evidence is lacking. Hence, a holistic approach to phenotyping requires specialized neuro-imaging as well as physiological investigations. Several general measures can help individuals with an abnormal detrusor contraction. The search for a molecule to enhance the detrusor voiding contraction remains elusive but there are promising new candidates. Neuromodulation can help select individuals but data is not well stratified by underlying etiology. Manipulation of central neurotransmitters might offer an alternate therapeutic option.

CONCLUSIONS

A better understanding of the underlying pathophysiologies behind an abnormality of the detrusor voiding contraction is needed for improving management. Towards this goal, the think-tank proposes a classification of the underactive detrusor that might help in selecting and reporting more well-defined patient cohorts.

Can we improve techniques and patients' selection for nerve stimulation suitable for lower urinary tract dysfunctions? ICI-RS 2023

AIMS

Lower urinary tract dysfunctions (LUTD) are very common and, importantly, affect patients' quality of life (QoL). LUTD can range from urinary retention to urgency incontinence and includes a variety of symptoms. Nerve stimulation (NS) is an accepted widespread treatment with documented success for LUTD and is used widely. The aim of this review is to report the results of the discussion about how to improve the outcomes of NS for LUTD treatment.

METHODS

During its 2023 meeting in Bristol, the International Consultation on Incontinence Research Society discussed a literature review, and there was an expert consensus discussion focused on the emerging awareness of NS suitable for LUTD.

RESULTS

The consensus discussed how to improve techniques and patients' selection in NS, and high-priority research questions were identified.

CONCLUSIONS

Technique improvement, device programming, and patient selection are the goals of the current approach to NS. The conditional nerve stimulation with minimally invasive wireless systems and tailored algorithms hold promise for improving NS for LUTD, particularly for patients with neurogenic bladder who represent the new extended population to be treated.

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.

Migration of a sacral neuromodulation electrode after vaginal delivery in a female patient with non-obstructive urinary retention

Sacral neuromodulation (SNM) is a well-established treatment in the management of refractory overactive bladder (OAB), non-obstructive retention, and fecal incontinence. However, the use and management of SNM in pregnant women remains elusive. We present a noteworthy case involving a patient diagnosed with Clara-Fowler syndrome who underwent SNM during the early stages of pregnancy. The sacral neuromodulator remained activated throughout the pregnancy upon patient's request. After vaginal delivery the patient encountered device dysfunction, ultimately attributed to electrode migration. After repositioning of a new electrode in the contralateral sacral root, the patient successfully recovered spontaneous voiding with no post void residual. This case suggests that SNM may not have detrimental effects on pregnancy or fetal development. However, the intricate physiological changes associated with pregnancy and vaginal delivery may contribute to electrode migration, warranting careful consideration in the management of pregnant patients undergoing SNM.

Feasibility of Sacral Neuromodulation in Patients With Underlying Neurologic Lower Urinary Tract Dysfunction and Fecal Incontinence

OBJECTIVE

To evaluate the efficacy and safety of sacral neuromodulation (SNM) in patients with underlying neurologic conditions and compare outcomes to non-neurogenic patients.

METHODS

Between 2017-2022 patients undergoing 2-staged implantation of InterStim II were included in a single-center retrospective study. Patients were allocated into two groups: underlying neurologic conditions (group 1) or non-neurogenic (group 2). Efficacy and safety were evaluated by comparing patients' bladder/bowel logs pre- and post-operative. Patients' demographics, indications, preimplantation urodynamic study variables, surgery duration, number of postop visits, and time to revision/removal procedures were compared and included in the data analysis.

RESULTS

Sixty-seven patients (64.2% female) with a mean age of 63.23 ± 14.15years were included in the study - 16/67(23.9%) patients assigned to group 1. There is no statistically significant difference between the groups regarding the indication for the treatment. The most common indication was nonobstructing urinary retention (NOUR) in both study groups. The common neurologic pathologies were multiple sclerosis, disc disease, and spinal stenosis. Overall and subgroup (based on an indication for SNM implantation) analyses showed no significant difference in patients' demographics, the surgery duration, or the chances for clinical success with a similar follow-up period. During the follow-up, the device was removed in 4 (25.0%) and 10 (19.6%) of the patients in group 1 and group 2, respectively (P = .912). There was no significant difference between the groups in the time till InterStim II removal (P = .905). All NOUR patients with clinical success in group 1 had an improvement of at least 75% from the baseline compared to 69% of patients in group 2 (P = .42). Univariate analysis in NOUR patients demonstrated that maximal cystometric capacity below 430 mL and the presence of detrusor contraction at voiding were statistically significant predictors of successful SNM. Overall, at the end of the follow-up period, 8 (50.0%) and 29 (56.9%) patients in groups 1 and 2, respectively, were defined as clinical success (P = .775).

Diabetic bladder dysfunction

More than 4.3 million people in the UK have been diagnosed with diabetes and there are thought to be a further 850 000 people living with diabetes who have not yet been diagnosed (Diabetes UK, 2024). Around half of all adults who have diabetes experience bladder dysfunction. It is one of the most common complications of diabetes, yet there is little in the medical literature and it is often unrecognised and poorly treated (Wittig et al, 2019). This article uses a case history approach to examine how diabetes can affect the bladder.

Detrusor Sphincter Dyssynergia

Detrusor sphincter dyssynergia (DSD) is defined as a detrusor contraction concurrent with an involuntary contraction of the urethral and/or periurethral striated muscles typically occurring in a patient with a spinal cord lesion above the sacral cord. Consequently, high urethral closure pressures during the detrusor contraction leads to high intravesical voiding pressure and large postvoid residuals, which can lead to significant complications in up to 50% of patients if DSD is not treated and followed-up regularly. DSD treatment options are centered around symptomatic management rather that addressing the underlying causative mechanisms.

One-stage implant in sacral neuromodulation for faecal incontinence - short-term outcome from a prospective study

AIM

Sacral neuromodulation (SNM) is approved for the treatment of faecal incontinence (FI) in a two-stage technique. With standardized implantation, approximately 90% of patients undergo successful Stage I operation and proceed to a permanent implant (Stage II). The aim of this work was to explore the feasibility of SNM as a one-stage procedure and report the 24-week efficacy.

METHOD

This study included patients diagnosed with idiopathic FI or FI due to an external anal sphincter defect ≤160° and one or more episodes of FI per week despite maximal conservative therapy. Patients were offered a one-stage procedure if a motor response of the external anal sphincter was achieved in three or more poles with at least one at ≤1.5 mA at lead placement. Patients were followed for 24 weeks. Their evaluation included the Wexner/St Mark's Incontinence Score, Faecal Incontinence Quality of Life score (FIQoL), a visual analogue scale (VAS) for assessing patient satisfaction and a bowel habit diary.

RESULTS

Seventy-three patients with a median age of 60 years (interquartile range 50-69 years) completed this prospective study. Episodes of FI were significantly reduced at the 24-week follow-up, from 13 (8-23) at baseline to 2 (0-5) (p-value = 0002). A ≥50% reduction in the number of FI episodes was achieved in 92% of participants. The Wexner score improved significantly from 16 (14-17) at baseline to 9 (5-13) (p-value < 0.001), and the St Mark's score improved significantly from 18 (16-20) to 11 (7-16) (p-value < 0.001). All domains in the FIQoL score and VAS for patient satisfaction improved significantly following the one-stage procedure.

CONCLUSION

A one-stage implantation procedure is feasible in selected patients with FI, significantly improving continence, quality of life and patient satisfaction after 24 weeks of follow-up.

Sacral neuromodulation therapy for urinary and defecatory disorders: experience in a Latin American public hospital

Objective

To show the experience of a Latin American public hospital, with SNM in the management of either OAB, NOUR or FI, reporting feasibility, short to medium-term success rates, and complications.

Methods

A retrospective cohort was conducted using data collected prospectively from patients with urogynecological conditions and referred from colorectal surgery and urology services between 2015 and 2022.

Results

Advanced or basic trial phases were performed on 35 patients, 33 (94%) of which were successful and opted to move on Implantable Pulse Generator (GG) implantation. The average follow-up time after definitive implantation was 82 months (SD 59). Of the 33 patients undergoing, 27 (81%)reported an improvement of 50% or more in their symptoms at last follow-up. Moreover, 30 patients (90%) with a definitive implant reported subjective improvement, with an average PGI-I "much better" and 9 of them reporting to be "excellent" on PGI-I.

Conclusion

SNM is a feasible and effective treatment for pelvic floor dysfunction. Its implementation requires highly trained groups and innovative leadership. At a nation-wide level, greater diffusion of this therapy among professionals is needed to achieve timely referral of patients who require it.

Baiona's Consensus Statement for Fecal Incontinence. Spanish Association of Coloproctology

Faecal incontinence (FI) is a major health problem, both for individuals and for health systems. It is obvious that, for all these reasons, there is widespread concern for healing it or, at least, reducing as far as possible its numerous undesirable effects, in addition to the high costs it entails. There are different criteria for the diagnostic tests to be carried out and the same applies to the most appropriate treatment, among the numerous options that have proliferated in recent years, not always based on rigorous scientific evidence. For this reason, the Spanish Association of Coloproctology (AECP) proposed to draw up a consensus to serve as a guide for all health professionals interested in the problem, aware, however, that the therapeutic decision must be taken on an individual basis: patient characteristics/experience of the care team. For its development it was adopted the Nominal Group Technique methodology. The Levels of Evidence and Grades of Recommendation were established according to the criteria of the Oxford Centre for Evidence-Based Medicine. In addition, expert recommendations were added briefly to each of the items analysed.

Radiation exposure during sacral neuromodulation lead placement: Multi-institutional descriptive study

OBJECTIVES

Fluoroscopy has significantly improved lead placement and decreased surgical time for implantable sacral neuromodulation (SNM). There is a paucity of data regarding radiation and safety of fluoroscopy during SNM procedures. Our study aims to characterize fluoroscopy time and dose used during SNM surgery across multiple institutions and assess for predictors of increased fluoroscopy time and radiation dose.

METHODS

Electronic medical records were queried for SNM procedures (Stage 1 and full implant) from 2016 to 2021 at four academic institutions. Demographic, clinical, and intraoperative data were collected, including fluoroscopy time and radiation dose in milligray (mGy). The data were entered into a centralized REDCap database. Univariate and multivariate analysis were performed to assess for predictive factors using STATA/BE 17.0.

RESULTS

A total of 664 procedures were performed across four institutions. Of these, 363 (54.6%) procedures had complete fluoroscopy details recorded. Mean surgical time was 58.8 min. Of all procedures, 79.6% were performed by Female Pelvic Medicine and Reconstructive Surgery specialists. There was significant variability in fluoroscopy time and dose based on surgical specialty and institution. Most surgeons (76.4%) were considered "low volume" implanters. In a multivariate analysis, bilateral finder needle testing, surgical indication, surgeon volume, and institution significantly predicted increased fluoroscopy time and radiation dose (p < 0.05).

CONCLUSIONS

There is significant variability in fluoroscopy time and radiation dose utilized during SNM procedures, with differences across institutions, surgeons, and subspecialties. Increased radiation exposure can have harmful impacts on the surgical team and patient. These findings demonstrate the need for standardized fluoroscopy use during SNM procedures.

Does choice of anesthesia during stage 1 sacral neuromodulation testing influence outcomes?

INTRODUCTION

Staged sacral neuromodulation (SNM) testing has been shown to have a high rate of progression to permanent implantation for the management of voiding dysfunction. Stage 1 lead placement (SNM-I) can be performed under monitored anesthesia care (MAC) or general anesthesia (GA). MAC allows for interpretation of sensory and motor responses to optimize lead placement while GA only permits for motor assessment. However, patient discomfort and movement can make lead placement challenging during MAC. Herein we evaluate whether the anesthesia type impacts the progression rate to permanent implantation (SNM-II).

MATERIALS AND METHODS

A retrospective chart review was performed for patients who underwent SNM-I in the operating room for wet overactive bladder between 2005 and 2023. Patients were divided into two groups based on the type of anesthesia used, MAC or GA. Clinical variables and progression to SNM-II were compared between cohorts. Progression to SNM-II was based on ≥50% symptomatic improvement during a 1-2 week trial period following SNM-I.

RESULTS

Of 121 patients included in the study, 95 (79%) underwent MAC and 26 (21%) GA for SNM-I. No difference in the progression rate to SNM-II was noted between groups (MAC, 68/95 patients, 72%; GA, 19/26, 73%; p = 0.39). We also found no difference when comparing the GA group to the 26 most recent MAC patients (MAC, 20/26 patients, 77%; GA, 19/26, 73%; p = 0.48).

CONCLUSION

Types of anesthesia for SNM-I did not affect rate of progression to SNM-II. The result lends support to the reliance on motor responses alone for lead placement during SNM-I.

Chronic Sacral Nerve Stimulation Inhibits Visceral Hypersensitivity in Diarrhea-Predominant Irritable Bowel Syndrome Rats Model

OBJECTIVE

Sacral nerve stimulation (SNS) is emerging as a novel treatment for irritable bowel syndrome (IBS). However, its effects are limited, and the underlying mechanisms remain largely unknown.

MATERIALS AND METHODS

In this study, rats were divided into three groups (n = 12 rats per group): 1) the SNS group; 2) the sham SNS group (the sham group for short); and 3) the control group. The SNS and sham groups were exposed to chronic and acute stress to establish an IBS model. Electrode implantation surgery was performed in rats with the IBS model. The SNS group received electrical stimulation for 30 minutes every day for seven days. Abdominal withdrawal reflex (AWR) was used to evaluate the effect of SNS on visceral sensitivity in diarrhea-predominant IBS (IBS-D) rats. The frequency domain of heart rate variability (HRV) was analyzed to assess the effect of SNS on regulating the autonomic function. The expression of transient receptor potential vanilloid 1 (TRPV1) in the colon, spinal cord, and hippocampus was detected by immunohistochemistry to explore the mechanism of SNS in IBS-D rats.

RESULTS

Compared with the sham group, AWR scores were significantly decreased under different gas volumes of stimulation of 0.4, 0.6, and 0.8 ml for rectal distention in the SNS group (all p < 0.05). However, there was no significant difference <1.0 ml between the two groups (p > 0.05). Compared with the sham group, the frequency domain indexes of HRV were significantly altered. Normalized low-frequency power and low frequency-to-high frequency ratio were significantly decreased, and normalized high-frequency power was significantly increased in the SNS group (all p < 0.05). Moreover, the expression of TRPV1 in the spinal cord and colon in the SNS group was significantly decreased compared with the sham group (both p < 0.05). These results suggested that chronic SNS not only improved the visceral sensitivity and autonomic dysfunction but also decreased the expression of TRPV1 in the spinal cord-gut tissue in IBS-D rats.

CONCLUSION

Chronic SNS was found to have an inhibitory effect on visceral hypersensitivity in IBS-D rats, providing experimental evidence for its potential clinical application in IBS.

Brain Response Induced by Peroneal Electrical Transcutaneous Neuromodulation Invented for Overactive Bladder Treatment, as Detected by Functional Magnetic Resonance Imaging

OBJECTIVES

In this study, we aimed to investigate whether peroneal electrical Transcutaneous Neuromodulation invented for overactive bladder (OAB) treatment elicits activation in brain regions involved in neural regulation of the lower urinary tract.

MATERIALS AND METHODS

Among 22 enrolled healthy female volunteers, 13 were eligible for the final analysis. Functional magnetic resonance imaging (fMRI) (Siemens VIDA 3T; Erlangen, Germany) was used to compare the brain region activation elicited by peroneal electrical Transcutaneous Neuromodulation with the activation elicited by sham stimulation. Each subject underwent brain fMRI recording during eight 30-second periods of rest, alternating with 30-second periods of passive feet movement using the sham device, mimicking the motor response to peroneal nerve stimulation. Subsequently, fMRI recording was performed during the analogic "off-on" stimulation paradigm using peroneal electrical transcutaneous neuromodulation. Magnetic resonance imaging data acquired during both paradigms were compared using individual and group statistics.

RESULTS

During both peroneal electrical Transcutaneous Neuromodulation and sham feet movements, we observed activation of the primary motor cortex and supplementary motor area, corresponding to the cortical projection of lower limb movement. During peroneal electrical Transcutaneous Neuromodulation, we observed significant activations in the brain stem, cerebellum, cingulate gyrus, putamen, operculum, and anterior insula, which were not observed during the sham feet movement.

CONCLUSIONS

Our study provides evidence that peroneal electrical Transcutaneous Neuromodulation elicits activation of brain structures that have been previously implicated in the perception of bladder fullness and that play a role in the ability to cope with urinary urgency. Our data suggest that neuromodulation at the level of supraspinal control of the lower urinary tract may contribute to the treatment effect of peroneal electrical Transcutaneous Neuromodulation in patients with OAB.

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.

Detailed Investigation of Bladder Diary Parameters During Sacral Neuromodulation in Patients With Overactive Symptoms

AIMS

Sacral neuromodulation (SNM) is a well-accepted, minimally invasive modality for patients with overactive bladder (OAB). Successful response to SNM is defined as at least 50% improvement in key symptoms, evaluated in a bladder diary (BD). BDs provide much useful information on bladder behavior during daily life. The aim of this study is to investigate BD parameter changes during SNM therapy in patients with OAB.

MATERIALS AND METHODS

The International Consultation on Incontinence Questionnaires (ICIQ)-BD was filled out by 34 patients with OAB, for three days at baseline and after three weeks of subthreshold sensory stimulation. The patients were considered responders for SNM when 50% improvement was seen in the BD. They underwent implantation of an internal pulse generator (IPG), and subsequently, an ICIQ-BD and a visual analog scale (VAS) evaluating bladder satisfaction during three days were filled out six weeks, six months, and one year after IPG implantation.

RESULTS

IPGs were implanted in 29 patients (85%). The BD showed a significant decrease in 24-hour leakage at three weeks from 4.2 to 0.6 (-86%, p < 0.001), similar significant decreases at six weeks and six months, and at one year (-80%). Voided volume (VV) at corresponding bladder sensation codes was not different between baseline and at three weeks of tined-lead procedure (TLP) (p > 0.05), and at six weeks (p > 0.05), six months (p > 0.1), and one year of IPG (p > 0.08). After three weeks of TLP, urgency episodes decreased from 4.8 to 3.4 (-30%, p = 0.025), with 59% reduction at six-weeks IPG (p < 0.001) and 49% at six-months IPG (p = 0.013). At one year, a decrease from 4.7 to 2.3 (52% reduction, p = 0.017) was noted. VAS showed the strongest correlation with urgency (p < 0.001) and frequency (p = 0.006). No significant correlation was found with VV (p = 0.87).

CONCLUSIONS

Our study describes how bladder sensation parameters change over time in patients on SNM. VV does not significantly increase, nor does frequency significantly decrease over the first year. Leaks and the percentage of urgency episodes significantly decrease, reaching a plateau level between six-weeks and six-months SNM.

Real-life after sacral nerve modulation implantation: Rate, reasons, and risk factors for mid-term follow-up discontinuation

OBJECTIVES

To evaluate follow-up after implantation of a sacral nerve modulation implantable pulse generator (IPG) and to investigate the reasons and risk factors for follow-up discontinuation.

MATERIALS AND METHODS

All patients who underwent an IPG implantation to treat lower urinary tract symptoms between 2014-2019 within 6 hospital centers located in the district of "Hauts-de-France" (France) were systematically called during the year 2020 for a standardized (tele)consultation. Patients were divided into 3 distinct profiles according to the regularity of their 5-year postoperative follow-up: "Regular follow-up", "Irregular follow-up" and "Lost to follow-up". The primary outcome was the change in the annual proportion of the 3 follow-up profiles over the 5 years following IPG implantation. As secondary outcomes we described the reasons reported for follow-up discontinuation and looked for risk factors associated with.

RESULTS

Overall, 259 patients were included. At the time of data collection, after a mean follow-up of 28.4 (± 19.8) months, 139 patients (53.7%) had a "Regular follow-up", 54 (20.8%) had an "Irregular follow-up" and 66 (25.5%) were "Lost to follow-up". The proportion of patients with a "Regular follow-up" decreased year by year, representing only 46.2% of patients at five-years. 175 patients (67.6%) underwent a standardized (tele)consultation. In multivariate analysis, only "lack of knowledge of the follow-up protocol" was statistically associated with follow-up discontinuation (OR=5.16; 95% CI [2.12-13.57]).

CONCLUSION

The proportion of patients followed up after IPG implantation decreased steadily over the years, often related to a lack of therapeutic education.

LEVEL OF EVIDENCE: 4

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.

[Intermittent catheterization: What are the environmental impacts and how can they be reduced?]

INTRODUCTION

If the use of intermittent catheterization has revolutionized the prognosis of neuro-urology patients, it seems necessary to question the ecological cost of single-use catheters, in a process of decarbonization of the health sector. The aim of this work is to identify the environmental impact of intermittent catheterization and potential solutions to reduce it.

METHODS

A review of the literature on the environmental impact of intermittent catheterizations was conducted. Potential solutions to reduce this impact and possible alternatives were then studied based on data from the literature.

RESULTS

Only two studies were identified. The first estimated the amount of waste generated by intermittent catheterization in the USA to be between 4400 and 38,964 tons per year. The second study showed a higher overall environmental impact of thermoplastic polyurethane (TPU) catheters than polyvinyl chloride (PVC) catheters and catheters made from polyolefin material. Reuse of catheters would reduce the amount of waste, but the paucity of data does not allow us to determine if the incidence of urinary tract infection would be affected. Alternative micturition methods, in addition to the complications they may cause, require the use of collection bags or pads, which also have an environmental impact. Other treatments for dysuria exist, but the evidence is limited and does not cover all patient populations.

CONCLUSION

With limited alternatives, it appears essential to develop more environmentally friendly catheters.

Technical and functional outcome after sacral neuromodulation using the "H" technique

BACKGROUND

Sacral neuromodulation (SNM) is a widely accepted treatment for pelvic floor disorders, including constipation and fecal incontinence (FI). In 2017, a standardized electrode placement method, the H technique, was introduced to minimize failure rates and improve clinical outcomes. We aimed to investigate the technical feasibility and functional outcome of the procedure.

METHODS

In this prospective study, we evaluated the first 50 patients who underwent SNM according to the H technique between 2017 and 2020 at a tertiary care hospital. Patient demographic and clinical data were collected, and the impact of various factors on patients' postoperative quality of life (QoL) was assessed after a follow-up of 40 months. Functional outcome was monitored prospectively using a standardized questionnaire.

RESULTS

Of 50 patients, 36 (72%) reported greater than 50% symptom relief and received a permanent implant (95% CI: 58.3-82.5). We observed 75% success in relieving FI (95% CI: 58.9-86.3) and 64% in constipation (95% CI: 38.8-83.7). Complication occurred in five (10%) patients. Preoperative vs. postoperative physical and psychological QoL, Vaizey score, and obstructed defecation syndrome (ODS) scores revealed significant improvements (all p < 0.01). Male gender was significantly associated with postoperative complications (p = 0.035).

CONCLUSION

We provide evidence for the technical feasibility and efficacy of the SNM implantation using the H technique. The medium-term results are promising for patients with FI and constipation. Male patients and those with a BMI > 25 are more prone to perioperative complications.

[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.

Cognitive impairment does not impact sacral neuromodulation implant rates for overactive bladder

OBJECTIVE

To evaluate the impact of cognitive impairment (CI) diagnoses on sacral neuromodulation (SNM) outcomes in older patients.

MATERIALS AND METHODS

We completed a retrospective review of all patients aged ≥55 years who underwent test-phase SNM (peripheral nerve evaluation (PNE) or stage 1) for overactive bladder (OAB) between 2014 and 2021 within a large multi-regional health system. Patient demographics, relevant comorbidities, CI diagnoses (dementia or mild CI), and SNM procedures were recorded. Logistic regression modeling was performed to evaluate the impact of CI on SNM implantation rates.

RESULTS

Five-hundred and ten patients underwent SNM test phase (161 PNE, 349 Stage 1) during the study period. The mean age was 71.0(8.5) years, and most (80.6%) were female. Overall, 52(10.1%) patients had a CI diagnosis at the time of SNM, and 30 (5.8%) were diagnosed at a median of 18.5 [9.25, 39.5] months after SNM. Patients with CI diagnoses were older, with more comorbidities, and were more likely to undergo PNE. Univariable comparison found no difference in implantation rate based on pre-SNM CI (85.4% vs. 76.9%, p = 0.16). Multivariable analysis identified PNE (OR 0.43, 95% CI 0.26-0.71), age (OR 0.96, 95%CI 0.93-0.98), and prior beta-3 agonist use (OR 0.60, 95% CI 0.37-0.99) but not CI or dementia as independent negative predictors of implantation. Implanted patients had a median follow-up of 25 [12.0, 55.0] months. Explant and revision rates did not differ according to CI.

CONCLUSION

Patients with OAB and CI diagnoses proceed to SNM implant at rates similar to patients without CI diagnoses. A diagnosis of CI should not necessarily exclude patients from SNM therapy for refractory OAB.

Effect of pulse width variations on sacral neuromodulation for overactive bladder symptoms: A prospective randomized crossover feasibility study

INTRODUCTION/BACKGROUND

The pulse width (PW) parameter in sacral neuromodulation (SNM) is understudied, with no evidence-based guidance available on optimal PW for urinary indications. The aim of this prospective, randomized, single-blinded, 3 × 3 cross over design study was to estimate the effect of two PW settings (60 µs, 420 µs) compared to the industry standard (210 µs) on SNM efficacy, quality of life, and device parameters in patients who were stable and satisfied with their SNM treatment.

METHODS/MATERIALS

Eligible patients were previously implanted and had urge incontinence or urgency-frequency with satisfaction on SNM at time of enrollment. Patients completed a 3-day voiding diary, validated questionnaires, and device interrogations with sensory threshold assessment at baseline and after a 4-week period on each of the three PW settings, to which they were randomized. Eighteen participants completed the study, as called for by power analysis.

RESULTS

Eighteen patients were enrolled in the study. Mean age was 68 years and implant duration at the time of participation was 4.4 years. While PW variations did not produce significant differences in overall objective outcomes, device parameters, including sensory threshold amplitude and battery life differed significantly. Shortened PW necessitated higher amplitude while conserving battery life. Stimulus sensation location, quality, and intensity did not differ between PW. Standard PW was chosen by 11 patients after the study, 5 chose extended, and 2 chose shortened. Those who chose alternative PW achieved significant reductions in urinary frequency from enrollment -2.23 voids/day (p = 0.015). Upon sub-analysis, patients reporting "much better" or "very much better" on extended PW achieved significant reductions in urinary frequency and nocturia at 5.6 and 0.4, compared to 8.5 and 2.16 at baseline (p = 0.005, p = <0.001). Whereas those reporting "much better" or "very much better" on shortened PW achieved significant reductions in urinary frequency at 5.15 compared to 7.35 (p = 0.026). There were no adverse events or complications.

CONCLUSIONS

Overall SNM effectiveness was unchanged with alternative PW; however, 39% of patients preferred alternative to standard PW and achieved significant improvements in urinary symptoms with such. Shorter PW can also provide savings in estimated battery life without sacrificing therapeutic efficacy.

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.

Innovative training modality for sacral neuromodulation (SNM): Patient-specific computerized tomography (CT) reconstructed 3D-printed training system: ICS School of Modern Technology novel training modality

INTRODUCTION

Sacral neuromodulation (SNM) is an effective treatment of urinary and bowel dysfunction, including secondary to neurological disorders. The learning curve for the optimal electrode placement for SNM is steep, expensive, and limited by patient factors such as obesity and previous injuries. We aim to create a patient specific 3-dimensional (3D) model for successful SNM training.

MATERIALS AND METHODS

A total of 26 urology residents who had different level of knowledge and experience were enrolled to the 3D SNM training program. The creation of 3D sacrum model has been started with evaluation of real patient computerized tomography images and creation of Digital Imaging and Communications in Medicine files. The segmented anatomic structures from the files then edited and stereolithographic files were generated for 3D-model prints via Mimics^© software. The 3D-printed models were used for training and evaluation of participants during the SNM intervention was performed. The evaluation of 3D SNM model training was led by one mentor who is expert on SNM.

RESULTS

On the preprinted 3D sacrum model all 26 participants were requested to perform the essential steps to complete a SNM procedure and individual procedure time was recorded. The mean and median scores were 18.8 and 19, respectively according to Likert scores (min 11 max 28).

CONCLUSIONS

SNM is increasing in popularity as a treatment option with physicians and patients with refractory symptoms. Few experienced specialists exist, and more effective training methods are needed to tackle the increasing demand, and individual patient anatomy.

Bullseye Technique to Optimize S3 Foramen Access: Applying a Trusted Endourology Technique to Pelvic Medicine

BACKGROUND

Sacral neuromodulation (SNM) is an advanced therapy that stimulates sacral spinal nerves to modulate bladder or bowel dysfunction and is approved for the treatment of overactive bladder, fecal incontinence, and non-obstructive urinary retention. Prior to implantation, a successful trial period must be performed via percutaneous nerve evaluation (PNE) or a staged trial to assess treatment efficacy. Ideal lead placement in the S3 foramen is imperative to produce an adequate response and successful outcome. Traditional lead placement with fluoroscopic guidance utilizes the anteroposterior (AP) and lateral views. In this abstract we describe an additional modification which may aid lead placement.

OBJECTIVE

This video demonstrates the bullseye technique to obtain S3 foramen access for optimal lead placement in SNM.

METHODS/MATERIAL

Begin the procedure by placing the patient in the prone position. The medial edges of the S3 foramen are marked bilaterally in the AP view followed by a horizontal marking at the level of S3. The pelvis is imaged with live fluoroscopy starting at 0 degrees and then rotating the C-arm to 30 degrees. This rotation allows the "opening up" of the S3 foramen from an ellipsoid to an oval. The surgeon grasps the needle with a Kelly clamp, placing it at the level of the skin approximately 2 cm cephalad from the horizontal marking. Live fluoroscopy is performed to align the needle with the image intensifier to form the bullseye. Once the correct angle is identified, the needle is advanced. The procedure is repeated on the contralateral foramen.

RESULTS

The bullseye technique allows quick and predictable access into S3. It can potentially decrease operating time, minimize needle entries in PNE, and allows the surgeon to access S3 while maintaining proper medial orientation.

CONCLUSION

The bullseye technique can assist surgeons in obtaining optimal access in SNM and can quickly be integrated into current practices.

Sacral Neuromodulation for Neurogenic Lower Urinary Tract Dysfunction

BACKGROUND: Neurogenic lower urinary tract dysfunction (NLUTD) is a highly prevalent and disabling condition; nevertheless, standard treatments often remain unsatisfactory. Sacral neuromodulation (SNM) is a well-established therapy for non-NLUTD, but there is a lack of randomized controlled trials to show benefit in patients with NLUTD. METHODS: For this sham-controlled, double-blind, multicenter trial, patients with refractory NLUTD (and intended SNM) were recruited at four Swiss SNM referral centers. After lead placement into the sacral foramina S3 (rarely, S4), all participants underwent SNM testing. If successful (≥50% improvement in key bladder diary variables), the neurostimulator was implanted for permanent stimulation. For 2 months, neuromodulation was optimized using subsensory stimulation with individually adjusted parameters. Thereafter, the neurostimulator remained on or was switched off (1:1 random allocation to group SNM ON or SNM OFF, respectively) for 2 months, followed by a neurourologic reevaluation. The primary outcome was success, as defined above, of SNM compared with baseline. RESULTS: Of 124 patients undergoing SNM testing, 65 (52%) had successfully improved lower urinary tract function. Of these, 60 patients (median age, 49.5 years; 43 women) were randomly assigned to the intervention. After 2 months of intervention, the SNM ON group demonstrated a success rate of 76%. In the SNM OFF group, 42% of patients showed sustained SNM effects despite their neurostimulator being switched off during the last 2 months (odds ratio, 4.35; 95% confidence interval, 1.43 to 13.21; P=0.009). During the entire study period, there were 11 adverse events (6 dropouts; no dropouts during the intervention phase). CONCLUSIONS: SNM effectively corrected refractory NLUTD in the short term in well-selected neurologic patients. (Funded by the Swiss National Science Foundation, Vontobel–Stiftung, Gottfried und Julia Bangerter–Rhyner Stiftung, Dr. Urs Mühlebach, and the Swiss Continence Foundation; ClinicalTrials.gov number, NCT02165774.)

Diagnosis and management of fecal incontinence in children and adolescents

Fecal incontinence (FI) is a commonly occurring disease of high concern. It is characterized by voluntary and involuntary defecation in children and adolescents. It is not only a physical disease but also a psychological and behavioral disorder. FI poses a serious burden on individuals and their families and therefore has become a social problem. Unfortunately, the management of FI among children is still a challenge because the etiology varies widely. Constipation has been found to be the most common cause, while sphincter dysfunction and neurogenic abnormalities may also play a role. Currently, no consensus guidelines exist, and the criteria for selecting optional methods remain unclear. It is therefore necessary to improve the efficacy of diagnosis and management strategies of FI in children. This review focused on the classification and etiology, discussed the diagnosis and management methods of FI in children and adolescents, and aimed to guide future studies.

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.

Video-urodynamics efficacy of sacral neuromodulation for neurogenic bladder guided by three-dimensional imaging CT and C-arm fluoroscopy: a single-center prospective study

To assess the efficacy of sacral neuromodulation (SNM) for neurogenic bladder (NB), guided by intraoperative three-dimensional imaging of sacral computed tomography (CT) and mobile C-arm fluoroscopy through video-urodynamics examination. We enrolled 52 patients with NB who underwent conservative treatment with poor results between September 2019 and June 2021 and prospectively underwent SNM guided by intraoperative three-dimensional imaging of sacral CT and mobile C-arm fluoroscopy. Video-urodynamics examination, voiding diary, quality of life questionnaire, overactive bladder symptom scale (OABSS) scoring, and bowel dysfunction exam were completed and recorded at baseline, at SNM testing, and at 6-month follow-up phases. Finally, we calculated the conversion rate from period I to period II, as well as the treatment efficiency and the occurrence of adverse events during the testing and follow-up phases. The testing phase of 52 NB patients was 18–60 days, with an average of (29.3 ± 8.0) days. Overall, 38 patients underwent SNM permanent electrode implantation, whose follow-up phase was 3–25 months, with an average of (11.9 ± 6.1) months. Compared with baseline, the voiding times, daily catheterization volume, quality of life score, OABSS score, bowel dysfunction score, maximum detrusor pressure before voiding, and residual urine volume decreased significantly in the testing phase. The daily voiding volume, functional bladder capacity, maximum urine flow rate, bladder compliance, and maximum cystometric capacity increased significantly in the testing phase. Besides, the voiding times, daily catheterization volume, quality of life score, OABSS score, bowel dysfunction score, maximum detrusor pressure before voiding, and residual urine volume decreased further from the testing to follow-up phase. Daily voiding volume, functional bladder capacity, maximum urine flow rate, bladder compliance, and maximum cystometric capacity increased further from testing to follow-up. At baseline, 10 ureteral units had vesicoureteral reflux (VUR), and 9 of them improved in the testing phase. Besides, there was 1 unit that further improved to no reflux during the follow-up phase. At baseline, 10 patients had detrusor overactivity (DO), and 8 of them improved in the testing phase. Besides, 1 patient’s symptoms further improved during the follow-up phase. At baseline, there were 35 patients with detrusor-bladder neck dyssynergia (DBND); 14 (40.0%) of them disappeared during the testing phase. Among 13 cases who had DBND in the testing phase, 6 (46.2%) disappeared during the follow-up phase. Of the 47 patients with detrusor-external sphincter dyssynergia (DESD) at baseline, 8 (17.0%) disappeared during the testing phase. Among 26 cases who had DESD in the testing phase, 6 (23.1%) disappeared during the follow-up phase. The effective rate of this study was 88.5% (46/52), and the conversion rate from phase I to phase II was 73.1% (38/52). Additionally, the efficacy in a short-term follow-up was stable. SNM guided by intraoperative three-dimensional imaging of sacral CT and mobile C-arm fluoroscopy is an effective and safe treatment option for NB in short time follow-up. It would be well improved in the bladder storage function, sphincter synergetic function and emptying efficiency by video-urodynamics examination in this study.

Trial registration: Chinese Clinical Trial Registry. ChiCTR2100050290. Registered August 25 2021. http://www.chictr.org.cn/index.aspx.

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

Evaluation of optical tracking and augmented reality for needle navigation in sacral nerve stimulation

BACKGROUND AND OBJECTIVE

Sacral nerve stimulation (SNS) is a minimally invasive procedure where an electrode lead is implanted through the sacral foramina to stimulate the nerve modulating colonic and urinary functions. One of the most crucial steps in SNS procedures is the placement of the tined lead close to the sacral nerve. However, needle insertion is very challenging for surgeons. Several x-ray projections are required to interpret the needle position correctly. In many cases, multiple punctures are needed, causing an increase in surgical time and patient's discomfort and pain. In this work we propose and evaluate two different navigation systems to guide electrode placement in SNS surgeries designed to reduce surgical time, minimize patient discomfort and improve surgical outcomes.

METHODS

We developed, for the first alternative, an open-source navigation software to guide electrode placement by real-time needle tracking with an optical tracking system (OTS). In the second method, we present a smartphone-based AR application that displays virtual guidance elements directly on the affected area, using a 3D printed reference marker placed on the patient. This guidance facilitates needle insertion with a predefined trajectory. Both techniques were evaluated to determine which one obtained better results than the current surgical procedure. To compare the proposals with the clinical method, we developed an x-ray software tool that calculates a digitally reconstructed radiograph, simulating the fluoroscopy acquisitions during the procedure. Twelve physicians (inexperienced and experienced users) performed needle insertions through several specific targets to evaluate the alternative SNS guidance methods on a realistic patient-based phantom.

RESULTS

With each navigation solution, we observed that users took less average time to complete each insertion (36.83 s and 44.43 s for the OTS and AR methods, respectively) and needed fewer average punctures to reach the target (1.23 and 1.96 for the OTS and AR methods respectively) than following the standard clinical method (189.28 s and 3.65 punctures).

CONCLUSIONS

To conclude, we have shown two navigation alternatives that could improve surgical outcome by significantly reducing needle insertions, surgical time and patient's pain in SNS procedures. We believe that these solutions are feasible to train surgeons and even replace current SNS clinical procedures.

Modulation of the autonomic nervous system by one session of spinal low-level laser therapy in patients with chronic colonic motility dysfunction

Patients with a defecation disorder may not evoke a normal defecation reflex, or the reflex may be excessive, as a dysfunction of the spinal autonomic nervous system. Treatment with various forms of lumbar and sacral neuromodulation have shown symptom improvement, but potential changes in autonomic functioning are rarely studied. Here we evaluate the effects on autonomic function of a single session of low-level laser therapy (LLLT) on the lumbar and sacral spine in 41 patients with chronic gastrointestinal motor dysfunction. The LLLT protocol used red LED light at a wavelength of 660 nm for 10 min and infrared LED light at a wavelength of 840 nm for 10 min, followed by infrared laser light at a wavelength of 825 nm for 10 min. Effects on the autonomic nervous system were assessed by measuring heart rate variability (HRV) changes. Respiratory Sinus Arrhythmia (RSA) and Root Mean Square of Successive Differences (RMSSD) were used to quantify parasympathetic reactivity; the Baevsky’s Stress Index (SI) reflected sympathetic activity while the ratios SI/RSA and SI/RMSSD were used to show shifts in autonomic dominance. The results indicate that lumbar and sacral neuromodulation using light arrays reduced, whereas stimulation by the laser probes significantly increased parasympathetic activity. The light arrays increased whereas the laser probes significantly decreased sympathetic activity (SI). The entire protocol shifted the autonomic balance toward parasympathetic activity. The comparison of actual vs. sham neuromodulation proved that the change in HRV parameters was due to actual light stimulation and not due to the arrays and probe touching the skin. In conclusion, a single session of LLLT markedly affects autonomic nervous system activity reflected in changes in HRV which is only possible by generating activity in the spinal autonomic nerves. These results warrant a study into the effects of LLLT on restoring autonomic dysfunction in chronic refractory colonic motility disorders.

Sacral neuromodulation: Rechargeable versus non-rechargeable device. What would the patient preferences be in France?

AIMS

Sacral neuromodulation (SNM) is a minimally invasive technique that provides effective treatment for the management of refractory overactive bladder (OAB), non-obstructive urinary retention (NOUR), and fecal incontinence (FI). This study assessed patient preferences between the currently available non-rechargeable SNM device and a new, full-body magnetic resonance imaging (MRI)-safe, smaller, rechargeable device.

METHODS

An online cross-sectional survey was conducted among French OAB, NOUR, FI patients, recruited via a market research vendor. To assess their preferences, patients were asked to indicate their level of agreement with 10 statements regarding the size of the device, its rechargeability, and the role of MRI using a 6-item Likert scale. A descriptive statistical analysis was performed.

RESULTS

In all, 95 patients (68% women), mean age 50 years, were included in the study: 51% were treated for OAB; 44% received an oral treatment and 28% had SNM. Overall, 71% of the 95 patients indicated a preference for the new device; 75% considered that recharging the device would not impact their lifestyle; 74% believed that the smaller size of the rechargeable device would facilitate their choice to be treated with SNM; 80% found full-body MRI compatibility important.

CONCLUSIONS

Most patients may prefer the new rechargeable SNM device over the current "standard". Compatibility with full-body MRI and the smaller device size seemed the key features of the newer device that would influence their choice of being treated with SNM. Future national and international recommendations should consider a shared decision-making process between the physician and the patient.

LEVEL OF EVIDENCE: 4

Is sacral nerve modulation reprogramming effective after permanent implantation for faecal incontinence?

AIM

Sacral nerve modulation (SNM) is recommended as a first-line surgical therapy for patients with faecal incontinence (FI). During patient follow-up, it is recommended that stimulation settings be reprogrammed to optimize patient outcomes. The aim of the present study was to evaluate the efficacy of stimulator reprogramming in patients with an implanted SNM device to treat FI.

METHOD

The data from patients who received a permanent SNM implant in a single centre from January 2008 to December 2019 were retrospectively analysed. Symptoms that occurred after implantation, the stimulator settings of the SNM device and changes made at each follow-up visit were noted. The efficacy of reprogramming was determined by assessing patient satisfaction.

RESULTS

Of the 117 patients (male/female 4/113; mean age 59.5 ± 11.8 years) with a SNM implant for FI, 84 (72%) had at least one symptom requiring reprogramming of the stimulator, most often during the first year after implantation (p = 0.05). The most frequently reported symptoms were loss of efficacy (68.5%; p = 1 × 10^-3 ) and pain (20.5%; p = 1 × 10^-3 ). Reprogramming was effective 53% of the time when treating loss of efficacy and 76% of the time when treating pain. When the stimulation parameters were reprogrammed at least four consecutive times to correct a symptom, the reprogramming was less effective in treating the symptom (p = 0.02).

CONCLUSION

Regular follow-up of patients with SNM device implants associated with reprogramming of stimulation parameters to improve the treatment of reported symptoms would optimize the efficacy of SNM.

Initial experience using the Axonics sacral neuromodulation system in patients with multiple sclerosis

INTRODUCTION

Sacral neuromodulation (SNM) is third-line therapy approved for urge urinary incontinence (UUI) and urgency, and nonobstructive urinary retention. Multiple sclerosis (MS) patients often suffer from neurogenic lower urinary tract dysfunction (NLUTD). The utility of SNM in the MS population is limited by magnetic resonance imaging (MRI) incompatibility as routine MRIs to evaluate for disease progression are required. The Axonics System is the first Food and Drug Administration-approved SNM device that is 1.5/3 T full-body MRI-conditionally safe. This study seeks to investigate the symptomatic improvement in MS patients after implantation of the Axonics System.

METHODS

All MS patients who elected for Axonics SNM from December 2019 to January 2021 were included. Demographics and scores were queried for urogenital distress inventory (UDI-6), incontinence impact questionnaire (IIQ-7), and global response assessment (GRA).

RESULTS

Fifteen MS patients with UUI were included. The time to follow-up averaged 121 days. On UDI-6, 12 patients reported improvement, 1 worsening, and 2 no change. Average UDI-6 scores before and after implantation were 56.6 and 25.2 (p < 0.0001). Improvements were significant for all questions under stress urinary incontinence, UUI, and voiding difficulty subcategories. On IIQ-7, 14 patients reported improvement and 1 reported worsening. Average IIQ-7 scores before and after implantation were 59.0 and 22.2 (p < 0.001). Improvements were significant for travel, social, and emotional subcategories, but not for physical activity. The average GRA score was 6 ("moderately improved").

CONCLUSION

The majority of MS patients reported significant initial improvement in UUI and associated quality of life measures on validated questionnaires after implantation of the Axonics System. Future studies are needed to determine the long-term outcomes and durability of this MRI full-body conditionally-safe system.

Neuromodulation for lower urinary tract symptoms in special populations

AIMS

Discuss the efficacy, safety, and future directions of neuromodulation in special populations of patients with neurological conditions.

METHODS

A literature review was done to find meta-analyses, review articles, studies, and case reports of the use of neuromodulation, either sacral neuromodulation or percutaneous tibial nerve stimulation, in patients with various neurological conditions of interest.

RESULTS

Sacral neuromodulation (SNM) and posterior tibial nerve stimulation (PTNS) appear to be safe and effective in special neurological populations of patients with multiple sclerosis (MS), Parkinson's disease (PD), and spinal cord injury (SCI). The majority of publications are smaller retrospective case series. Outcomes appear similar to those seen in nonneurogenic patients but also partly depend on disability progression. Magnetic resonance imaging (MRI) compatibility has helped to improve eligibility for SNM in these special populations.

CONCLUSIONS

In a small number of studies, SNM and PTNS appear to be safe and effective in special neurological populations of patients with MS, PD, and SCI. MRI compatibility has helped to improve eligibility for SNM in these special populations. Studies looking at SNM are limited by a small number of subjects, lack of prospective trials, and selection bias. Larger, randomized studies with long-term follow up are needed to better predict response to SNM and PTNS in these populations.

Radiologically anatomic measurement analysis for the third sacral foramen and an efficient implantation protocol for sacral neuromodulation

AIMS

To define radiologically anatomic measurements for the S3 foramen and develop an efficient and straightforward implantation protocol for sacral neuromodulation (SNM) in a southern Chinese population.

METHODS

We retrospectively reviewed 793 adults without sacrococcygeal abnormalities or bony injury. We generated CT-derived three-dimensional volumetric models and collected radiologically anatomic measurements of S3 foramen. A multiple generalized linear regression model was applied to evaluate implantation protocol for SNM.

RESULTS

Height, weight, and sacral height were significantly different between enrolled patients based on sex (p < 0.001 for all), while age and sacral width were similar. The measurements L1, L2, A1, and A2 on both sides were similar, while based on sex, those of L1, A1, A2 showed significant differences [7.02 ± 0.90 (M) vs. 6.10 ± 0.99 cm (F) (p < 0.001); 83.05 ± 6.23 (M) vs. 82.08 ± 7.53° (F) (p = 0.005); and 13.31 ± 5.69 (M) vs. 11.97 ± 4.91° (F) (p < 0.001), respectively]. The multiple generalized linear regression model demonstrated that sex was a common independent factor for estimating L1, L2, A1, A2, while the consistency rate between the estimated model and actual measurements was poor. The measurements L1, L2, A1, and A2 were approximately 7.0 cm (M) versus 6.1 cm (F), 1.8 cm (M) versus 1.8 cm (F), 83° (M) versus 82° (F), and 13° (M) versus 12° (F), respectively.

CONCLUSIONS

This retrospective study indicates that the radiologically anatomic measurements for the S3 foramen have unique characteristics. Our study provides an efficient and straightforward implantation protocol for SNM, improving its use in China.