Sacral Neuromodulation: Standardized Electrode Placement Technique

Pediatric sacral neuromodulation: A step-by-step tined lead placement technique and clinical outcomes

INTRODUCTION

Chronic stimulation of the sacral nerves has become one of the most accepted non-invasive treatments for non-neurogenic lower urinary tract dysfunction in children. The International Children's Continence Society recently recognized sacral neuromodulation (SNM) as a viable option for treating urinary incontinence related to overactive bladder (OAB) and urgency. Proper placement of the electrodes is a key factor in optimizing clinical outcomes.

OBJECTIVE

We present a video that offers a step-by-step demonstration of the tined lead placement technique in children and share our experience with this procedure in a pediatric cohort.

STUDY DESIGN

Retrospective, non-randomized study.

RESULTS

Since 2020, seven children have undergone SNM for idiopathic OAB (n = 4, median age: 8.5 years) and chronic non-neurogenic urinary retention (n = 3, median age: 16 years). Six of the seven children progressed to permanent implantation after a successful test phase. The median follow-up duration was 39 months (8-48) and 18 months (18-42) respectively in the OAB and urinary retention group. All children were successfully treated. Two patients required surgical revision due to wound infection and device dysfunction. The SNM device was removed in one patient, with no recurrence of OAB symptoms.

DISCUSSION

Key elements of tined lead placement include identifying radiological landmarks, guiding the electrode into the sacral foramen, and ensuring its correct progression. Placement is based on fluoroscopic appearance of the electrodes and achieving motor and sensory responses during stimulation. These factors contribute to the positive clinical outcomes seen in our pediatric cohort.

CONCLUSION

SNM appears to be an effective and minimally invasive treatment option for pediatric patients with non-neurogenic vesico-sphincter disorders that are resistant to first-line therapies. Standardization of the surgical technique is essential for optimizing patient outcomes and maximizing the therapeutic potential of SNM.

Sacral Neuromodulation for Neurogenic Lower Urinary Tract, Bowel and Sexual Dysfunction in Patients With Multiple Sclerosis: A Pilot Trial

AIMS

We present results of a two-arm pilot study assessing the feasibility of conducting a double-blind randomized controlled trial (RCT) to evaluate the efficacy of sacral neuromodulation (SNM) in patients with multiple sclerosis (MS) suffering from neurogenic lower urinary tract dysfunction (NLUTD).

METHODS

Eligible subjects with refractory NLUTD and EDSS < 5 underwent SNM test phase. Those showing more than a 50% improvement of bladder variables, received implantable pulse generators (IPG) and were randomized to either treatment group (IPG ON) or to sham group (IPG OFF) for 1 month. During second month, all patients had the IPG ON until the end of the trial. The primary endpoints were trial feasibility, recruitment potential, and response rate at the end of SNM test phase. Secondary endpoint was safety. Changes in key bladder diary-derived variables and patient reported outcomes were recorded as well.

RESULTS

Thirty-two patients were screened, 17 were eligible and 13 were included in the SNM test phase. Eleven were considered responders and were implanted with IPG. Subsequently, six patients were randomized to the treatment group and five to the sham group. No serious adverse events were reported. In the intervention phase, both objective and subjective improvements were seen in the treatment group, while the symptoms in the sham group remained mostly unchanged. At study completion, six patients reported being completely satisfied, three were mostly satisfied, and two were indifferent to the treatment.

CONCLUSIONS

This pilot trial demonstrated feasibility of double-blind RCT assessing safety and efficacy of SNM in MS patients.

TRIAL REGISTRATION

ClinicalTrials. gov NCT05380856.

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.

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.

Management of Fecal Incontinence: Surgical Treatment Options

Background

Fecal incontinence (FI) is a frequent, often underestimated, health issue in adults. Its treatment is primarily nonsurgical. Only if conservative options fail to result in adequate symptom reduction should surgery be considered. We present an overview of historical and current surgical treatment options.

Summary

Well-known sphincter replacement techniques such as dynamic graciloplasty and the artificial bowel sphincter are no longer used because of their invasiveness and relevant comorbidity. Today, sphincteroplasty and sacral neuromodulation (SNM) are the most common procedures recommended in current guidelines. The therapeutic choice is based on diagnostic findings. Sphincteroplasty is an option only in patients with an anal sphincter lesion and has only moderate long-term success. SNM has become the established first choice in multiple pathophysiological conditions resulting in FI, as it has proved highly successful with minimal invasiveness. Over time, the spectrum of indications has evolved and the technique is now successful in morphological sphincter defects as well.

Key Messages

The spectrum of surgical options to treat FI is limited. Owing to its efficacy and low comorbidity, SNM is now considered the gold standard in multiple pathophysiological and morphological conditions, whereas sphincteroplasty remains an option in patients with FI from a defined sphincter lesion.

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.

Effectiveness of sacral neuromodulation with 3D printing and ultrasound localization for treating neurogenic bladder in patients with pelvic structural anomalies

OBJECTIVE

To assess the efficacy and safety of Sacral Neuromodulation (SNM) in conjunction with 3D printing and ultrasound localization for treating patients with neurogenic bladder and pelvic structural anomalies.

METHODS

This prospective study involved 56 patients diagnosed with neurogenic bladder and pelvic anomalies. They were treated with SNM from January 2022 to December 2023. Patients were split into study and control groups based on the origins of their pelvic anomalies, with each group comprising 28 individuals. The study group underwent preoperative 3D printing and intraoperative ultrasound-assisted puncture, whereas the control group utilized intraoperative X-ray-assisted puncture. Metrics compared included the number of punctures, average puncture duration, intraoperative SNS tuning time, effective initial voltage, postoperative testing duration, phase two conversion rates, and the incidence of bleeding and infection.

RESULTS

The study group experienced significantly fewer punctures compared to the control group (2.21 ± 0.92 vs 9.29 ± 4.37) (P < 0.01), had a shorter average puncture duration (5.71 ± 2.69 min vs. 28.60 ± 9.69 min) (P < 0.01), and required a lower effective initial voltage (0.87 ± 0.23v vs. 1.38 ± 0.52v) (P < 0.01). X-ray exposure was eliminated in the study group, in contrast to 11.51 ± 4.62 mAs in the control group(P < 0.01). The phase two implantation rates were 67.8 % for the study group and 57.1 % for the control group(P = 0.04). No surgery-related complications occurred in either group.

CONCLUSION

Combining preoperative 3D printing with intraoperative ultrasound-assisted puncture significantly improves the accuracy of SNM placement, reduces surgery time, and eliminates X-ray exposure for both doctors and patients. This method is both safe and effective for patients with neurogenic bladder and pelvic anomalies.

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.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Brain Responses Difference between Sexes for Strong Desire to Void: A Functional Magnetic Resonance Imaging Study in Adults Based on Graph Theory

Background: The alternations of brain responses to a strong desire to void were unclear, and the gender differences under the strong desire to void remain controversial. The present study aims to identify the functional brain network's topologic property changes evoked by a strong desire to void in healthy male and female adults with synchronous urodynamics using a graph theory analysis. Methods: The bladders of eleven healthy males and eleven females were filled via a catheter using a specific infusion and withdrawal pattern. A resting-state functional magnetic resonance imaging (fMRI) was performed on the enrolled subjects, scanning under both the empty bladder and strong desire to void states. An automated anatomical labeling (AAL) atlas was used to identify the ninety cortical and subcortical regions. Pearson's correlation calculations were performed to establish a brain connection matrix. A paired t-test (p < 0.05) and Bonferroni correction were applied to identify the significant statistical differences in topological properties between the two states, including small-world network property parameters [gamma (γ) and lambda (λ)], characteristic path length (Lp), clustering coefficient (Cp), global efficiency (Eglob), local efficiency (Eloc), and regional nodal efficiency (Enodal). Results: The final data suggested that females and males had different brain response patterns to a strong desire to void, compared with an empty bladder state. Conclusions: More brain regions involving emotion, cognition, and social work were active in females, and males might obtain a better urinary continence via a compensatory mechanism.

NRV: An open framework for in silico evaluation of peripheral nerve electrical stimulation strategies

Electrical stimulation of peripheral nerves has been used in various pathological contexts for rehabilitation purposes or to alleviate the symptoms of neuropathologies, thus improving the overall quality of life of patients. However, the development of novel therapeutic strategies is still a challenging issue requiring extensive in vivo experimental campaigns and technical development. To facilitate the design of new stimulation strategies, we provide a fully open source and self-contained software framework for the in silico evaluation of peripheral nerve electrical stimulation. Our modeling approach, developed in the popular and well-established Python language, uses an object-oriented paradigm to map the physiological and electrical context. The framework is designed to facilitate multi-scale analysis, from single fiber stimulation to whole multifascicular nerves. It also allows the simulation of complex strategies such as multiple electrode combinations and waveforms ranging from conventional biphasic pulses to more complex modulated kHz stimuli. In addition, we provide automated support for stimulation strategy optimization and handle the computational backend transparently to the user. Our framework has been extensively tested and validated with several existing results in the literature.

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).

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.

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.

Neuromodulation Techniques in Chronic Refractory Coccydynia: A Narrative Review

Refractory coccydynia is a condition characterized by severe coccygeal pain and poses a challenging management dilemma for clinicians. Advancements in neuromodulation (NM) technology have provided benefits to people experiencing chronic pain that is resistant to standard treatments. This review aims to summarize the spectrum of current NM techniques employed in the treatment of refractory coccydynia along with their effectiveness. A review of studies in the scientific literature from 2012 to 2023 was conducted, revealing a limited number of case reports. Although the available evidence at this time suggests significant pain relief with the utilization of NM techniques, the limited scope and nature of the studies reviewed emphasize the need for large-scale, rigorous, high-level research in this domain in order to establish a comprehensive understanding of the role of NM and its effectiveness in the management of intractable coccydynia.

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.

[Prolonged spinal and sacral neurostimulation in children with pelvic organ dysfunction: preliminary analysis]

OBJECTIVE

To evaluate the clinical efficacy of long-term spinal and sacral programmable neurostimulation for pelvic organ dysfunction in patients with myelodysplasia and chronic dysfunction of the bladder and rectum.

MATERIAL AND METHODS

A retrospective study included 32 children aged 1-17 years (mean 10.7) with myelodysplasia, pelvic organ dysfunction and ineffective therapy including botulinum therapy and exclusion of tethered spinal cord syndrome. All children underwent comprehensive urodynamic examination with analysis of bladder and residual urine volume, mean flow rate, intravesical pressure and total urine volume, as well as electromyographic examination. Examination was carried out before surgery, after 6, 12 and 36 months. We applied urinary diary, NBSS questionnaire and urodynamic examination data. All patients underwent neurological examinations (neurological status, magnetic resonance imaging of the spinal cord, computed tomography and radiography of the spine, electroneuromyography). The study was conducted at the neurosurgical department of the Republican Children's Clinical Hospital in Ufa between 2014 and 2022. There were 32 implantations of epidural neurostimulators for pelvic organ dysfunctions.

RESULTS

Patients used epidural spinal and sacral stimulation up to 6 times a day for 10-15 min turning on the pulse generator. This method significantly increased urinary volume, decreased episodes of urinary leakage and fecal incontinence, residual volume after urination and number of periodic catheterizations compared to baseline data. Sixteen patients were very satisfied, 10 ones were moderately satisfied, and 2 patients were not satisfied with therapy. The number of bladder catheterizations per day decreased by 51.1%. Urine volume significantly increased from 131.5±16.1 to 236±16.7 ml, intravesical pressure decreased from 23.5±4.2 to 18.5±2.1 cm H2O (by 20.3%).

CONCLUSION

Chronic epidural spinal and sacral stimulation can improve the quality of life in patients with pelvic organ dysfunction. This technique may be effective for pelvic organ dysfunction caused by myelodysplasia.

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.

Infection Rate of a Prolonged Sacral Neuromodulation Test: A Large Retrospective Study

OBJECTIVES

It is estimated that 3.8% to 12.5% of patients develop a device infection during the two to four weeks of the sacral neuromodulation (SNM) test, leading to removal of the entire system. It is possible to prolong the test phase up to the clinician's decision, particularly when benefits are unclear. The aim of our study is to assess the device infection rate in a prolonged SNM test.

MATERIALS AND METHODS

We retrospectively enrolled patients who performed a prolonged SNM test (at least eight weeks) in the last five years (2017-2021). All procedures were performed using a standardized technique and the same prophylactic antibiotic protocol. In case of a clinical suspicion of infection, all components were explanted. Patient information (age at implantation, medical history of diabetes, metabolic syndrome, immunologic diseases, or chronic immunosuppressive therapy), surgical data (operative time, intraoperative complications), and infection data (timing of onset, symptoms reported, wound culture results) were recorded.

RESULTS

We enrolled 232 patients who underwent a prolonged SNM test (mean duration 65.5 days). A local infection that led to the removal of the entire system occurred in six patients (2.6%). The gluteal pocket was always involved, and in two cases, infection was also extended to the exit point of the extension wire. No significant correlations with clinical data were found. Infection occurred beyond four weeks in two cases, between three and four weeks in three cases, and within two weeks in one case. Intraoperative wound culture was performed in five of six patients, and Staphylococcus aureus (S aureus) was isolated in four cases. One culture test gave negative bacterial growth results.

CONCLUSIONS

The infection rate of a prolonged eight-week SNM test is low and does not differ from that reported in the literature for a two-to-four-week SNM test. S aureus remains the most frequent bacterium involved.

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.

Long-term cost-effectiveness analysis of sacral neuromodulation in the treatment of severe faecal incontinence

AIM

The aim of this study was to evaluate the long-term cost-effectiveness of sacral neuromodulation in the treatment of severe faecal incontinence as compared with symptomatic management.

METHODS

In the public health field, a micro-costing evaluation method was conducted from the perspectives of the health system and the society. The incremental cost-effectiveness ratio was used as a decision index, and we considered various scenarios to evaluate the impact of the cost of symptomatic management and percutaneous nerve evaluation success rate in its calculation. Clinical data were retrieved from a consecutive cohort of 93 patients with severe faecal incontinence undergoing sacral neuromodulation after a failure of conservative (pharmacological and biofeedback) and/or surgical (sphincteroplasty) first-line treatments were considered.

RESULTS

The long-term incremental cost-effectiveness ratio comparing sacral neuromodulation versus symptomatic management was 14347€/QALY and 28523€/QALY from the societal and health service provider's perspectives, respectively. If the definitive pulse generator implant success rate was 100%, incremental cost-effectiveness would correspond to 6831€/QALY and 16761€/QALY, respectively.

CONCLUSIONS

Sacral neuromodulation may be considered a cost-effective technique in the long-term treatment of severe faecal incontinence from the societal and health care sector perspectives. Improving patient selection and determining the predictive outcome factors for successful sacral neuromodulation in the treatment of faecal incontinence would improve cost-effectiveness.

Five-year Results from the Prospective, Multicenter, Observational SOUNDS Study of Patients with Overactive Bladder Treated with the InterStim System for Sacral Neuromodulation

BACKGROUND

Although sacral neuromodulation (SNM) for overactive bladder (OAB) is an established therapy, there is a lack of high-quality, long-term data on real-life practice.

OBJECTIVE

To report on real-life therapeutic effectiveness, quality of life (QoL), disease severity, and safety as well as patient-reported symptom bother after approximately 5 yr of follow-up.

DESIGN, SETTING, AND PARTICIPANTS

A total of 291 OAB patients were enrolled at 25 French sites according to local standard of care. Sacral neuromOdUlation with InterStim therapy for intractable lower uriNary tract DySfunctions (SOUNDS) enrolled both de novo and replacement patients, and a total of 229 patients were permanently implanted.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Over the course of the study, patients were followed up six times with two follow-ups in the year after implantation and annually thereafter. Of the patients, 154 completed the final follow-up after a mean of 57.7 ± 3.9 mo.

RESULTS AND LIMITATIONS

The mean number of daily leaks in urinary urge incontinence (UI) patients was reduced from 4.4 ± 3.3 at baseline to 1.8 ± 2.6 after 5 yr in de novo and from 5.4 ± 4.9 to 2.2 ± 3.0 in replacement patients (both p < 0.001). Likewise, the number of voids in urinary frequency patients was reduced compared with baseline (de novo: reduced from 12.6 ± 4.0 [baseline] to 9.6 ± 4.3 [5 yr]; replacements: reduced from 11.5 ± 4.3 [baseline] to 9.2 ± 3.1 [5 yr]; both p < 0.05). Complete continence rates after 5 yr were 44% (25/57) in de novo and 33% (5/15) in replacement UI patients, and 68% (39/57) and 67% (10/15) of UI patients were categorized as therapy responders by showing a >50% improvement in leaks. Disease severity (Urinary Symptom Profile domain 2), Numeric Rating Scale-based symptom bother, and disease-specific QoL (Ditrovie) improved significantly in both groups at all visits (p < 0.001). Adverse events related to device or procedure occurred in 51% (140/274) of patients, with 66% (152/229) of the events being classified as minor (Clavien-Dindo grade I and II). Surgical revisions were reported in 39% (89/229), which include permanent explants in 15% (34/229) of patients.

CONCLUSIONS

SOUNDS demonstrates the sustained effectiveness and QoL improvements of SNM in OAB patients after 5 yr in real-world conditions while maintaining an acceptable safety profile consistent with literature.

PATIENT SUMMARY

This study confirmed that French overactive bladder patients had a sustained symptom and bother reduction, and improvements in quality of life up to 5 yr after sacral neuromodulation device implantation.

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 nerve modulation for patients with fecal incontinence: long-term outcome and effects on sexual function

Sacral nerve modulation has become an established treatment for fecal and urinary incontinence, and sexual disorders. The objective of this study was to evaluate the long-term outcome of sacral neuromodulation in patients with fecal or combined fecal and urinary incontinence (double incontinence), assessing its safety, efficacy, and impact on quality of life and sexual function. This was a multicentric, retrospective, cohort study including patients with fecal or double incontinence who received sacral neuromodulation at seven European centers between 2007 and 2017 and completed a 5-year follow-up. The main outcome measures included improvements of incontinence symptoms and quality of life compared with baseline, evaluated using validated tools and questionnaires at 1-, 6-, 12-, 36- and 60-month follow-up. 108 (102 women, mean age 62.4 ± 13.4 years) patients were recruited, of whom 88 (81.4%) underwent definitive implantation of the pacemaker. Patients' baseline median Cleveland Clinic Incontinence Score was 15 (10-18); it decreased to 2 (1-4) and 1 (1-2) at the 12- and 36-month follow-up (p < 0.0001), remaining stable at the 5-year follow-up. Fecal incontinence quality of life score improved significantly. All patients with sexual dysfunction (n = 48) at baseline reported symptom resolution at the 5-year follow-up. The study was limited by the retrospective design and the relatively small patient sample. Sacral nerve modulation is an effective treatment for fecal and double incontinence, achieving satisfactory long-term success rates, with resolution of concomitant sexual dysfunction.

Sacral neuromodulation for low anterior resection syndrome: current status-a systematic review and meta-analysis

INTRODUCTION

It is estimated that approximately 70% of patients with rectal cancer who undergo surgery will suffer from Low Anterior Resection Syndrome (LARS). In the last decades, sacral neuromodulation (SNM) has been widely used in urinary dysfunction and in faecal incontinence refractory to medical treatment. Its application in LARS has been investigated and has shown promising results. The paper's aim is to present a systematic review and meta-analysis of the available literature and evaluate the therapeutic success of SNM in patients with LARS.

METHODS

A systematic search was performed in international health-related databases: Cochrane Library, EMBASE, PubMed and SciELO. No restrictions on year of publication or language were applied. Retrieved articles were screened and selected according to set inclusion criteria. Data items were collected and processed for each included article and a meta-analysis was done according to the PRISMA guidelines. The primary outcome was the number of successful definitive SNM implants. Further outcomes included changes in bowel habits, incontinence scores, quality of life scores, anorectal manometry data and complications.

RESULTS

A total of 18 studies were included, with 164 patients being submitted to percutaneous nerve evaluation (PNE) with 91% responding successfully. During follow-up of therapeutic SNM some devices were explanted. The final clinical success rate was 77% after permanent implant. Other outcomes, such as the frequency of incontinent episodes, faecal incontinence scores, quality of life scores were overall improved after SNM. The meta-analysis showed a decrease in 10.11 incontinent episodes/week; a decrease of 9.86 points in the Wexner score and an increase in quality of life of 1.56 (pooled estimate). Changes in anorectal manometry were inconsistent. Local infection was the most common post-operative complication, followed by pain, mechanical issues, loss of efficacy and haematoma.

DISCUSSION/CONCLUSION

This is the largest systematic review and meta-analysis concerning the use of SNM in LARS patients. The findings support the available evidence that sacral neuromodulation can be effective in the treatment of LARS, with significant improvement in total incontinent episodes and patients´ quality of life.

[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.

Sacral neuromodulation in the management of chronic pelvic pain: A systematic review and meta-analysis

INTRODUCTION

Sacral neuromodulation (SNM) is a treatment approved for use in several conditions including refractory overactive bladder (OAB) and voiding dysfunction. Chronic pelvic pain (CPP) is a debilitating condition for which treatment is often challenging. SNM shows promising effect in patients with refractory CPP. However, there is a lack of clear evidence, especially in long-term outcomes. This systematic review will assess outcomes of SNM for treating CPP.

METHODS

A systematic search of MEDLINE, Embase, Cochrane Central and clinical trial databases was completed from database inception until January 14, 2022. Studies using original data investigating SNM in an adult population with CPP which recorded pre and posttreatment pain scores were selected. Primary outcome was numerical change in pain score. Secondary outcomes were quality of life assessment and change in medication use and all-time complications of SNM. Risk of bias was assessed using the Newcastle Ottawa Tool for cohort studies.

RESULTS

Twenty-six of 1026 identified articles were selected evaluating 853 patients with CPP. The implantation rate after test-phase success was 64.3%. Significant improvement of pain scores was reported in 13 studies; three studies reported no significant change. WMD in pain scores on a 10-point scale was -4.64 (95% confidence interval [CI] = -5.32 to -3.95, p < 0.00001) across 20 studies which were quantitatively synthesized: effects were maintained at long-term follow-up. Mean follow-up was 42.5 months (0-59). Quality of life was measured by RAND SF-36 and EQ-5D questionnaires and all studies reported improvement in quality of life. One hundred and eighty-nine complications were reported in 1555 patients (Clavien-Dindo Grade I-IIIb). Risk of bias ranged from low to high risk. Studies were case series and bias stemmed from selection bias and loss to follow-up.

CONCLUSION

Sacral Neuromodulation is a reasonably effective treatment of Chronic Pelvic Pain and significantly reduces pain and increases patients' quality of life with immediate to long-term effects.

Robot-assisted laparoscopic pyeloplasty in an adult with pelvic ectopic kidney with hydronephrosis: a case report and literature review

Pelvic ectopic kidney is a congenital anomaly with a higher probability of hydronephrosis than a normal kidney. Few studies have reported cases of pelvic ectopic kidney with hydronephrosis in adults treated with robot-assisted laparoscopic pyeloplasty (RALP). We performed RALP on a 22-year-old male and he recovered well after the procedure. The patient's pain disappeared after surgery. No complications occurred during the perioperative period and had a rapid postoperative recovery.

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.

Pathway Of Low Anterior Resection syndrome relief after Surgery (POLARiS) feasibility trial protocol: a multicentre, feasibility cohort study with embedded randomised control trial to compare sacral neuromodulation and transanal irrigation to optimised conservative management in the management of major low anterior resection syndrome following rectal cancer treatment

INTRODUCTION

Rectal cancer is common with a 60% 5-year survival rate. Treatment usually involves surgery with or without neoadjuvant chemoradiotherapy or adjuvant chemotherapy. Sphincter saving curative treatment can result in debilitating changes to bowel function known as low anterior resection syndrome (LARS). There are currently no clear guidelines on the management of LARS with only limited evidence for different treatment modalities.

METHODS AND ANALYSIS

Patients who have undergone an anterior resection for rectal cancer in the last 10 years will be approached for the study. The feasibility trial will take place in four centres with a 9-month recruitment window and 12 months follow-up period. The primary objective is to assess the feasibility of recruitment to the POLARiS trial which will be achieved through assessment of recruitment, retainment and follow-up rates as well as the prevalence of major LARS.Feasibility outcomes will be analysed descriptively through the estimation of proportions with confidence intervals. Longitudinal patient reported outcome measures will be analysed according to scoring manuals and presented descriptively with reporting graphically over time.

ETHICS AND DISSEMINATION

Ethical approval has been granted by Wales REC1; Reference 22/WA/0025. The feasibility study is in the process of set up. The results of the feasibility trial will feed into the design of an expanded, international trial.

TRIAL REGISTRATION NUMBER

CT05319054.

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.

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.

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

BACKGROUND

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

OBJECTIVE

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

DESIGN, SETTING, AND PARTICIPANTS

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

INTERVENTION

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

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

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

RESULTS AND LIMITATIONS

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

CONCLUSIONS

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

PATIENT SUMMARY

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

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.

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.

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.

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.

Faecal incontinence in adults

Faecal incontinence, which is defined by the unintentional loss of solid or liquid stool, has a worldwide prevalence of ≤7% in community-dwelling adults and can markedly impair quality of life. Nonetheless, many patients might not volunteer the symptom owing to embarrassment. Bowel disturbances, particularly diarrhoea, anal sphincter trauma (obstetrical injury or previous surgery), rectal urgency and burden of chronic illness are the main risk factors for faecal incontinence; others include neurological disorders, inflammatory bowel disease and pelvic floor anatomical disturbances. Faecal incontinence is classified by its type (urge, passive or combined), aetiology (anorectal disturbance, bowel symptoms or both) and severity, which is derived from the frequency, volume, consistency and nature (urge or passive) of stool leakage. Guided by the clinical features, diagnostic tests and therapies are implemented stepwise. When simple measures (for example, bowel modifiers such as fibre supplements, laxatives and anti-diarrhoeal agents) fail, anorectal manometry and other tests (endoanal imaging, defecography, rectal compliance and sensation, and anal neurophysiological tests) are performed as necessary. Non-surgical options (diet and lifestyle modification, behavioural measures, including biofeedback therapy, pharmacotherapy for constipation or diarrhoea, and anal or vaginal barrier devices) are often effective, especially in patients with mild faecal incontinence. Thereafter, perianal bulking agents, sacral neuromodulation and other surgeries may be considered when necessary.

Comparison of surgical techniques for optimal lead placement in sacral neuromodulation: a cadaver study

Background

Sacral neuromodulation (SNM) is a common treatment for patients with urinary and faecal incontinence. A close contact of the tined lead electrode with the targeted nerve is likely to improve functional outcome.

The aim of this study was to compare the position of the SNM lead in relation to the sacral nerve by comparing different implantation techniques.

Methods

This cadaver study was conducted at the Division of Anatomy of Vienna's Medical University in October 2020. We dissected 10 cadavers after bilateral SNM lead implantation (n = 20), using two different standardized implantation techniques. The cadavers were categorized as group A (n = 10), representing the conventional guided implantation group and group B (n = 10), where SNM implantation was conducted with the novel fluoroscopy-guided “H”-technique. The primary goal was to assess the distance between the sacral nerve and the lead placement.

Results

The electrodes were inserted at a median angle of 58.5° (46–65°) in group A and 60° (50–65°) in group B, without reaching statistical significance. In 8 cadavers, the lead entered the S3 foramen successfully.

The median distance of the lead to the nerve did not show a significant difference between both groups (E0: Group A: 0.0 mm vs. Group B: 0.0 mm, p = 0.969; E1: Group A: 0.0 mm vs. Group B: 0.5 mm p = 0.754; E2: Group A: 2.5 mm vs. Group B: 2.5 mm p = 1.000; E3: Group A: 3.5 mm vs. Group B: 4.0 mm p = 0.675). In 2 cases (20%) of the conventional group A, the lead was misplaced and located at the gluteal muscle.

Perforation of the presacral fascia was observed in one lead placement in group A and in two placements in group B.

Conclusions

Both standardized implantation techniques may ensure close electrode proximity to the targeted nerve. Misplacement of the electrode was more often observed with the conventional implantation technique.

Ageing with sacral nerve modulation for fecal incontinence: how many patients get benefit after more than 10 years?

Sacral nerve modulation (SNM) has represented a major advancement in the minimally invasive management of patients with fecal incontinence (FI). Although the success rate in the short–medium term has widely been demonstrated, the very long-term outcomes are poorly investigated. This study aims to assess the effectiveness of SNM in a cohort of patients with a follow-up longer than 10 years. Clinical records of patients submitted to SNM for FI in our tertiary referral colorectal Unit between 1998 and 2010 were retrospectively reviewed looking for status of the implantable pulse generator (IPG), follow-up duration, severity of FI by the St Marks’ score and quality of life. 58 patients fulfilled the entry criteria and 36 (58%, median follow-up, 12 years) accepted to take part to the telephone interview, while 22 (38%) were lost to the follow-up. Nineteen patients had their IPG removed (Group A) while 17 (27%) had the SNM still active after a median follow-up of 13 years (Group B). In the group A, the median baseline St Marks’ score was 13 and did not change after the IPG removal. In group B, the median baseline St Marks’ score was 14, at last IPG substitution, it was of 7 and at the last follow-up dropped to 4. In the group A, the median SF-12 physical and mental scores did not change significantly while they improved significantly in group B. A progressive deterioration of the success rate of SNM with the time has been documented after a very long-term follow-up.

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.

Long-term results of sacral neuromodulation for the treatment of anorectal diseases

INTRODUCTION

Sacral neuromodulation (SNM) aims to improve anorectal function in patients with disorders of anal continence and rectal emptying. The mechanism of action of SNM is not well known, and its indications are still under evaluation. We report the functional results and morbidity of a prospective cohort treated between 2002 and 2019.

RESULTS

A total of 284 patients (of 423 tested) had implantation of a SNM. Five patients (1.8%) were lost to follow-up. Among those who had implantation, the indications for SNM were anal incontinence (n=376), refractory constipation (n=17), anterior resection syndrome (n=13), solitary rectal ulcer syndrome (n=7), and chronic inflammatory bowel disease (IBD) (n=10). The morbidity rate was 2.7% (Dindo-Clavien>2), 33 patients (11%) required explantation for infection (n=5), pain (n=2), inefficacy (n=24) or other reasons (rectal cancer) (n=3). It was necessary to change the stimulator in 68 patients (24%) during the follow-up period. Regarding the group of patients with anal incontinence, functional results showed improvement of the incontinence score in 40% and of quality of life in 25% after a mean follow-up of 55months.

CONCLUSION

SNM constitutes a mini-invasive treatment associated with low morbidity. Its' efficacy in anal incontinence makes it a priority approach. Other indications are still under evaluation; while results are promising, they are highly variable.

Electrophysiological Responses in the Human S3 Nerve During Sacral Neuromodulation for Fecal Incontinence

Intra-operative electrode placement for sacral neuromodulation (SNM) relies on visual observation of motor contractions alone, lacking complete information on neural activation from stimulation. This study aimed to determine whether electrophysiological responses can be recorded directly from the S3 sacral nerve during therapeutic SNM in patients with fecal incontinence, and to characterize such responses in order to better understand the mechanism of action (MOA) and whether stimulation is subject to changes in posture. Eleven patients undergoing SNM were prospectively recruited. A bespoke stimulating and recording system was connected (both intraoperatively and postoperatively) to externalized SNM leads, and electrophysiological responses to monopolar current sweeps on each electrode were recorded and analyzed. The nature and thresholds of muscle contractions (intraoperatively) and patient-reported stimulation perception were recorded. We identified both neural responses (evoked compound action potentials) as well as myoelectric responses (far-field potentials from muscle activation). We identified large myelinated fibers (conduction velocity: 36–60 m/s) in 5/11 patients, correlating with patient-reported stimulation perception, and smaller myelinated fibers (conduction velocity <15 m/s) in 4/11 patients (not associated with any sensation). Myoelectric responses (observed in 7/11 patients) were attributed to pelvic floor and/or anal sphincter contraction. Responses varied with changes in posture. We present the first direct electrophysiological responses recorded from the S3 nerve during ongoing SNM in humans, showing both neural and myoelectric responses. These recordings highlight heterogeneity of neural and myoelectric responses (relevant to understanding MOA of SNM) and confirm that electrode lead position can change with posture.

Sacral Neuromodulation Changes Pelvic Floor Activity in Overactive Bladder Patients-Possible New Insights in Mechanism of Action: A Pilot Study

OBJECTIVES

To evaluate if electrodiagnostic tools can advance the understanding in the effect of sacral neuromodulation (SNM) on pelvic floor activity, more specifically if SNM induces changes in pelvic floor muscle (PFM) contraction.

MATERIALS AND METHODS

Single tertiary center, prospective study (October 2017-May 2018) including patients with overactive bladder syndrome undergoing SNM. Electromyography of the PFM was recorded using the Multiple Array Probe Leiden. The procedure consisted of consecutive stimulations of the lead electrodes with increasing intensity (1-3, 5, 7, 10 V). Recordings were made after electrode placement (T0) and three weeks of SNM (T1). Patients with >50% improvement were defined as responders, others as nonresponders. For the analyses, the highest electrical PFM response (EPFMR), defined as the peak-to-peak amplitude of the muscle response, was identified for each intensity. The sensitivity (intensity where the first EPFMR was registered and the normalized EPFMR as percentage of maximum EPFMR) and the evolution (EMFPR changes over time) were analyzed using linear mixed models.

RESULTS

Fourteen patients were analyzed (nine responders, five nonresponders). For nonresponders, the PFM was significantly less sensitive to stimulation after three weeks (T0: 1.7 V, T1: 2.6 V). The normalized EPFMR was (significantly) lower after three weeks for the ipsilateral side of the PFM for the clinically relevant voltages (1 V: 36%-23%; p = 0.024, 2 V: 56%-29%; p = 0.00001; 3 V: 63%-37%; p = 0.0002). For the nonresponders, the mean EPFMR was significantly lower at 8/12 locations at T1 (T0: 109 μV, T1: 58 μV; mean p = 0.013, range <0.0001-0.0867). For responders, the sensitivity and evolution did not change significantly.

CONCLUSIONS

This is the first study to describe in detail the neurophysiological characteristics of the PFM, and the changes over time upon sacral spinal root stimulation, in responders and nonresponders to SNM. More research is needed to investigate the full potential of EPFMR as a response indicator.

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

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

DISCUSSION

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

Optogenetic Neuromodulation of the Urinary Bladder

OBJECTIVES

Nerve stimulation and neuromodulation have become acceptable interventions for bladder dysfunction. However, electrical stimulation indiscriminately affects all types of cells and can lead to treatment failure and off-target effects. In recent years, advancement of knowledge of optogenetics provides a powerful tool to enable precise, minimally invasive neuromodulation.

MATERIALS AND METHODS

In this review, we introduce basic knowledge about optogenetics; discuss the progression of engineered opsins, gene-targeting methods, and light-delivery approaches; we also summarize the application of optogenetics in neuromodulation of the bladder and discuss the possible clinical translation in the future.

RESULTS AND CONCLUSION

Optogenetics offers a powerful tool to investigate the neural circuit of bladder storage and voiding and provides a promising approach for manipulating neurons and muscles. It is possible to achieve coordinated modulation of the bladder and its sphincter through a "closed-loop" system. Optogenetics neuromodulation could also be applied in urinary bladder control in the clinic in the future.