Continuing trial responsibilities for implantable neural devices

Participants of neural implant studies have research-related posttrial care needs (e.g., hardware replacements). Gaps in plans for posttrial care are currently common, which can have major consequences for patients. Professionals and organizations involved should address important unmet posttrial needs.

Intraoperative Neurophysiological Monitoring During Spinal Cord Stimulation Surgery: A Systematic Review

OBJECTIVES

This study aims to describe the state of literature regarding the use of intraoperative neurophysiological monitoring (IONM) during spinal cord stimulator surgery.

MATERIALS AND METHODS

A systematic review of the use of IONM during spinal cord stimulation (SCS) surgery was performed using the following three data bases: PubMed, Ovid MEDLINE, and Embase. Research techniques included systematic research following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol by Cochrane, and backward searching. Qualitative analysis of included articles was performed using the methodologic index for nonrandomized studies assessment tool. Direction of effect, consistency across studies, and cost-effectiveness were narratively synthesized.

RESULTS

A total of 15 records were identified through data base searching. All records used IONM methods under general anesthesia for guidance of epidural lead placement. IONM techniques used for determining lateralization in the found articles were compound muscle action potentials (CMAPs) (n = 8), somatosensory evoked potentials (SSEPs) (n = 3) or both (n = 4). Motor evoked potentials were used in three trials for neuroprotection purposes. Two studies were comparative, and 12 were noncomparative.

CONCLUSIONS

We found a good body of level II evidence that using IONM during SCS surgery is a valid alternative to awake surgery and may even be superior regarding pain management, cost-effectiveness, and postoperative neurologic deficits. In direct comparison, the found evidence suggested using CMAP provided more consistently favorable results than using SSEP for midline placement of epidural leads under general anesthesia. Selection of IONM modality should be made on the basis of pathophysiology of disease, individual IONM experience, and the individual patient.

Intraoperative Predictors of Sacral Neuromodulation Implantation and Treatment Response: Results From the ROSETTA Trial

PURPOSE

We determined the utility of intraoperative data in predicting sacral neuromodulation outcomes in urgency urinary incontinence.

MATERIALS AND METHODS

Intraoperative details of sacral neuromodulation stage 1 were recorded during the prospective, randomized, multicenter ROSETTA trial, including responsive electrodes, amplitudes, and response strengths (motor and sensory Likert scales). Stage 2 implant was performed for stage 1 success on 3-day diary with 24-month follow-up. An intraoperative amplitude response score for each electrode was calculated ranging from 0 (no response) to 99.5 (maximum response, 0.5 V). Predictors for stage 1 success and improvement at 24 months were identified by stepwise logistic regression confirmed with least absolute shrinkage and selection operator and stepwise linear regression.

RESULTS

Intraoperative data from 161 women showed 139 (86%) had stage 1 success, which was not associated with number of electrodes generating an intraoperative motor and/or sensory response, average amplitude at responsive electrodes, or minimum amplitude-producing responses. However, relative to other electrodes, a best amplitude response score for bellows at electrode 3 was associated with stage 1 failure, a lower reduction in daily urgency urinary incontinence episodes during stage 1, and most strongly predicted stage 1 outcome in logistic modeling. At 24 months, those who had electrode 3 intraoperative sensory response had lower mean reduction in daily urgency urinary incontinence episodes than those who had no response.

CONCLUSIONS

Specific parameters routinely assessed intraoperatively during stage 1 sacral neuromodulation for urgency urinary incontinence show limited utility in predicting both acute and long-term outcomes. However, lead position as it relates to the trajectory of the sacral nerve root appears to be important.

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

INTRODUCTION/BACKGROUND

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

METHODS/MATERIALS

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

RESULTS

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

CONCLUSIONS

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

Development of an implant technique and early experience using a novel implantable pulse generator with a quadripolar electrode array at the tibial nerve for refractory overactive bladder

OBJECTIVES

Tibial nerve stimulation is an effective treatment for overactive bladder (OAB) and has been utilized as an in-person recurring session treatment option for many years. The primary objective of this study was to evaluate the safety and efficacy of a long-term implantable device and the method of utilizing a retrograde approach to place the device (a percutaneous implantable pulse generator [pIPG] with integrated quadripolar electrodes) at the tibial nerve (Protect PNS; Uro Medical Corp.).

METHODS

A novel retrograde implant technique was developed through multiple cadaveric dissections to percutaneously implant a chronic, wireless, minimally invasive pIPG device with integrated quadripolar electrodes (now licensed to Uro Medical) at the tibial nerve. A proof-of-concept pIPG device approved as part of an FDA IDE was designed to gain early experience in subjects with refractory OAB. The pIPG was implanted in the office under local anesthesia using the novel retrograde approach, and stimulation was activated using an external wireless energy source called a transmitter. Initially, a pilot study was designed to compare outcomes in subjects randomized to either percutaneous tibial nerve stimulation (PTNS) or Protect PNS. However, due to the small sample sizes available at this time, it was not possible to compare the two groups. Thus, the purpose of this manuscript is to describe the outcome of subjects who underwent implantation of the Protect PNS system. Twelve-month safety and efficacy were evaluated.

RESULTS

Nine subjects were enrolled in the randomized pilot study; 5 to the pIPG group and 4 to PTNS, and all completed the 13-week primary endpoint. Subsequently, two subjects in the PTNS group chose to cross over and have the pIPG implanted after 13 weeks. Outcomes of the seven subjects who underwent implantation of the pIPG are described. No complications related to the office procedure were noted. Two of the older model pIPG devices became nonresponsive at 1 and 4 weeks and were replaced. Six minor adverse events were reported and resolved. Subjects reported improvement in urge urinary incontinence (UUI) episodes, OAB symptoms, and quality of life. Subjects impanted with a pIPG reported a 50% reduction in UUI as early as 1 week.

CONCLUSIONS

Results of this pilot study suggest that retrograde percutaneous implantation of a pIPG is a safe, minimally invasive one-stage office procedure for treatment for urge incontinence related OAB symptoms, without significant complications after 12 months follow-up. Future studies will be required to compare outcomes among treatment modalities.

A case report of sacral neuromodulation tined lead migration into the rectum

This report describes a 26-year-old woman who underwent sacral neuromodulation explant following lead migration and rectal wall penetration. Her device was implanted due to persistent urinary retention. The tined lead wire was dissected to the fascia and cut. The rectal part of the lead was removed with gentle traction.

Ultrasound-guided percutaneous peripheral nerve stimulation for chronic refractory neuropathic pain: a unique series

During the last two decades, with the advent of recent technology, peripheral nerve stimulation has become an appealing modality at the forefront of pain management. In this case series, we document the clinical rationale and technical considerations on three of the most challenging cases, refractory to previous interventions, that were treated by our team with an ultrasound-guided percutaneous peripheral nerve stimulator targeting the musculocutaneous, bilateral greater occipital and subcostal nerves. At the 6-month follow-up, all patients experienced greater than 50% relief of baseline pain, with a near-complete resolution of pain exacerbations. Furthermore, to our knowledge, this is the first report of an ultrasound-guided percutaneous technique of a peripheral nerve stimulator targeting the musculocutaneous and subcostal nerves.

Upper Airway Stimulation in Patients with Obstructive Sleep Apnea: Long-Term Surgical Success, Respiratory Outcomes, and Patient Experience

Introduction  Upper airway stimulation (UAS) with electric activation of the hypoglossal nerve has emerged as a promising treatment for patients with moderate-to-severe obstructive sleep apnea. Objective  To retrospectively analyze objective and subjective outcome measures after long-term follow-up in obstructive sleep apnea patients receiving upper airway stimulation. Methods  An observational retrospective single-center cohort study including a consecutive series of patients diagnosed with obstructive sleep apnea receiving upper airway stimulation. Results  Twenty-five patients were included. The total median apnea-hypopnea index (AHI) significantly decreased from 37.4 to 8.7 events per hour at the 12-month follow-up ( p  < 0.001). The surgical success rate was 96%. Adverse events were reported by 28% of the patients. Conclusion  Upper airway stimulation is an effective and safe treatment for obstructive sleep apnea in patients with continuous positive airway pressure (CPAP) failure or intolerance. However, it is possible that the existing in and exclusion criteria for UAS therapy in the Netherlands have positively influenced our results.

Current advances in neuromodulation techniques in urology practices: A review of literature

Neuromodulation has become a valid therapeutic option for patients with various lower urinary tract disorders. In clinical practice, the most used and recommended neuromodulation techniques are sacral neuromodulation (SNM), pudendal neuromodulation (PN), and percutaneous tibial nerve stimulation (PTNS). There are many theories concerning the mechanism of action of neuromodulation. Although SNM, PN, and PTNS show their activities through different nerve roots, all provide central and peripheral nervous system modulations. SNM has been approved for the treatment of overactive bladder (OAB), nonobstructive urinary retention, and fecal incontinence, while PTNS has been approved for OAB treatment. However, they are also used off-label in other urinary and nonurinary pelvic floor disorders, such as neurogenic lower urinary system disorder, interstitial cystitis, chronic pelvic pain, and sexual dysfunction. Minor and nonsurgical reversible complications are usually seen after neuromodulation techniques. In addition, in the last few years, there have been various developments in neuromodulation technology. Some of the examples of these developments are rechargeable batteries with wireless charging, improvements in programing, less invasive single-stage implantation in outpatient settings, and lower-cost new devices. We performed a literature search using Medline (PubMed), Cochrane Library, EMBASE, and Google scholar databases in the English language from January 2010 to February 2021. We included reviews, meta-analyses, randomized controlled trials, and prospective and retrospective studies to evaluate the activities and reliability of SNM, PN, and PTNS and the developments in this area in the last decade based on the current literature.

Magnetic resonance imaging scans in patients with dorsal root ganglion stimulation

OBJECTIVE

Patients fitted with a neurostimulator face a greater need to undergo magnetic resonance imaging (MRI) scans. Given the lack of literature in this regard, this study aims to review our experience with MRI examinations on patients implanted with a dorsal root ganglion stimulation (DRG-S) system and their potential adverse events.

MATERIALS AND METHODS

We conducted a retrospective analysis of the prospective treatment documentation gathered from November 2011 to October 2020. We identified 259 MRI registrations for patients with an implanted neurostimulation system; the MRI examinations were performed using a 1.5 Tesla MRI system in accordance with a structured scheme.

RESULTS

Among the 259 MRI registrations identified in this study, 28 corresponded to patients with an implanted DRG-S system. In 2 cases, no MRI scan was performed, and thus, only 26 MRI examinations were evaluated in detail. The DRG-S device was approved for the requested MRI scans in only 2 of these 26 cases (7.7%). In addition, 2 minor adverse events (syncopal episode and connection problem) were identified, and only the second problem (3.8%) was related to neurostimulator operation.

CONCLUSIONS

Necessary MRI examinations in patients with DRG-S systems are rarely covered by the European CE/US Food and Drug Administration (CE/FDA) approval. Although the manufacturer recommendations are against the use of MRI in patients with implanted DRG-S in certain conditions, we performed these scans without causing injury to the patient or damaging the device. Given that data on safety are limited, MRIs should be conducted study related. We provide recommendations for the procedure that should be followed when an MRI is needed urgently.

The role of neuromodulation in chronic functional constipation: a systematic review

BACKGROUND

Chronic functional constipation is a highly prevalent disorder in which, when conservative measures fail to relieve symptoms, surgical interventions are sometimes indicated. In recent years, neuromodulation for the treatment of functional constipation has gained interest but its role and effectiveness are still unclear. The purpose of this review is to provide a systematic overview on the current literature on the different modalities of neurostimulation and their effect on chronic functional constipation in adults as reported in the literature.

METHODS

A search in the literature for articles concerning the effect of different types of neuromodulation on constipation was performed in PubMed using extensive search terms for the different modalities of neuromodulation. Studies and trials were checked for eligibility. For all types of neuromodulation together, 27 articles were included.

RESULTS

17 studies were included on SNM (sacral nerve modulation). Although multiple studies show positive results on the effect of SNM in constipation, double-blind crossover RCT's (randomised controlled trials) showed no significant effect. 3 studies were included for tSNS (transcutaneous sacral nerve stimulation), 2 for PTNS (percutaneous tibial nerve stimulation) and 2 for TTNS (transcutaneous tibial nerve stimulation). Studies and trials on these modalities of neuromodulation reported ambiguous results on statistical significance of the effect. For transcutaneous IFC (interferential current therapy) 2 studies were included, which both reported a statistically significant effect on all outcomes.

CONCLUSION

The beneficial effect of neuromodulation in chronic functional constipation remains questionable. However, neuro-modulation might be worth considering in patients refractory to treatment before turning to more invasive measures. Future research should shed more light on the effects of neuromodulation in constipation.

Electrical neuromodulation in bladder dysfunction: Mapping the state-of-the-art with bibliometric analysis of field and top 100 cited articles

AIMS

Electrical neuromodulation of bladder function has been extensively investigated in the literature. To date, there has been no characterization of the field, and there is a lack of bibliometric literature to guide future studies. We directed this scientometric analysis to characterize the distribution, characteristics and relationships of the field, with subanalysis of top 100 articles.

METHODS

The Web of Science Core Collection of the Thompson Reuters Web of Science was searched and analyzed to determine distributions and characteristics of clinical research investigating electrical neuromodulation in bladder dysfunction. Field citation and coauthorship networks were mapped, and recent citation bursts of the past decade are described. The top 100 cited articles were categorized, with level of evidence rating system applied.

RESULTS

A total of 872 articles published from 1949 until October 2020 were included in field analysis. Europe demonstrated the highest continental productivity within field (n = 539, 61.81%), and the United States the top nation (35.55% of field, 39.24% of top 100 articles). The Journal of Urology has historically published the most articles in the field (n = 150, 17.20%), and top 100 articles (n = 41, 40.20%). Top 100 articles reported studies of neuromodulation effects via sacral neuromodulation (n = 59); of non-neurological bladder dysfunction (n = 72); urinary incontinence (n = 92), frequency (n = 73) and urgency (n = 68) symptomology.

CONCLUSIONS

Analysis of electrical neuromodulation of bladder dysfunction literature reveals historical development, core research clusters and relationships, and an increase in publication activity over past decades.

Pivotal Study of Leadless Tibial Nerve Stimulation with eCoin® for Urgency Urinary Incontinence: An Open-Label, Single Arm Trial

PURPOSE

A novel leadless tibial nerve stimulator provides a primary battery-powered, coin-sized, minimally invasive option to deliver automatic low-duty cycle stimulation for overactive bladder syndrome therapy. A pivotal trial was conducted to evaluate the safety and efficacy of this investigational device, eCoin®, for treating refractory urgency urinary incontinence.

MATERIALS AND METHODS

This was a prospective, open-label, single arm trial carried out at 15 U.S. medical centers involving 137 subjects with refractory urgency urinary incontinence. After implantation in the lower leg above the fascia over the tibial nerve, eCoin delivered automated stimulation sessions for the duration of the study. The primary efficacy measure was the proportion of subjects who achieved a 50% or greater reduction from baseline in urgency urinary incontinence episodes after 48 weeks of therapy. The primary safety measure was device-related adverse events at the same time point.

RESULTS

Of 137 subjects enrolled, 133 were implanted with eCoin, and 132 were included in the intention-to-treat population. Of those 132 subjects, 98% were female, mean±SD age was 63.9±10.9 years, and baseline daily urgency urinary incontinence episodes were 4.3±3.1. The primary efficacy analysis showed 68% (95% CI: 60%-76%) of subjects experienced at least a 50% reduction in urgency urinary incontinence episodes at 48 weeks post-activation; 16% of implanted subjects experienced device-related events through 52 weeks post-implantation.

CONCLUSIONS

eCoin demonstrated clinical benefit for treating overactive bladder syndrome with automatic delivery of an intermittent low-duty cycle and implanted with a minimally invasive, brief procedure.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

A Supervised 3 Weeks Test Phase in Sacral Neuromodulation with a 1-Year Followup

PURPOSE

We sought to determine whether prolonged interventional test phase increases cumulative success rate and compared success rates between early responders (ie within 1 week) and those in need for reprogramming (due to lack of efficacy) of sacral neuromodulation after 1-year followup.

MATERIALS AND METHODS

In a single tertiary center prospective study (August 2015 to November 2018) 90 patients refractory to first line treatment were eligible for sacral neuromodulation, including 48 overactive bladder wet (53%), 8 overactive bladder dry (9%) and 34 nonobstructive urinary retention (38%). Patients were evaluated at weekly intervals during test phase and those not successful were reprogrammed. This could be repeated after the second week. Primary outcome was success rate after 3-week test phase and after 1-year followup. Statistical analysis was done by nonparametric tests for numeric (Mann-Whitney U) and categorical (chi²) data.

RESULTS

After 3 weeks of test period 56 patients (62%) were considered successful. Prolonged interventional testing increased cumulative success. A 1-year followup showed no significant difference in success rate between early responders and those in need for reprogramming (chi², p=0.562). There was no difference in age (Mann-Whitney U, p=0.222), sex (chi², p=0.952) or indication (chi², p= 0.975).

CONCLUSIONS

A 3-week test phase with close followup increases cumulative success rate. During this supervised 3-week test phase 42% of the initial nonresponders after the first week became successful candidates after reprogramming. Patients who required this additional programming did equally as well as those without need for reprogramming. A supervised 3-week test phase is therefore strongly recommended.

Hypoglossal Nerve Stimulator Placement for Pediatric Trisomy 21 Patients with Refractory Obstructive Sleep Apnea: A Case Series

BACKGROUND

Hypoglossal nerve stimulators (HNS) are an increasingly popular form of upper airway stimulation for obstructive sleep apnea (OSA) in adults who are unable to tolerate positive pressure treatment. However, HNS use is currently limited in the pediatric population.

CASE PRESENTATION

We present a case series detailing the anesthetic management of three pediatric trisomy 21 patients receiving HNS for refractory obstructive sleep apnea. The patients tolerated the procedure well and experienced no complications. The average obstructive apnea-hypopnea index (AHI) change was 87.4% with the HNS.

CONCLUSIONS

Proper anxiolysis, safe and controlled induction, multimodal analgesia, and minimization of post-operative respiratory compromise are all necessary to ensure anesthetic and surgical success. After a tailored anesthetic regimen, proper device placement and close follow-up, our patients had a marked improvement in obstructive symptoms.

3-Year Followup of a New Implantable Tibial Nerve Stimulator for the Treatment of Overactive Bladder Syndrome

PURPOSE

We evaluated the 3-year safety and efficacy of the BlueWind Medical RENOVA™ iStim system for the treatment of overactive bladder syndrome.

MATERIALS AND METHODS

All patients who previously underwent implantation with the RENOVA system were offered continued participation. The primary long-term study end point was to evaluate the safety profile based on incidence of serious adverse events (system and/or procedure related), which was measured by the impact and frequency of serious adverse events. The secondary end points included clinical improvement compared to baseline and quality of life improvement compared to baseline at 36 months, which was measured by 3-day voiding diary and quality of life questionnaires at certain time points.

RESULTS

Of the 34 patients with overactive bladder syndrome who previously underwent implantation with the RENOVA system 20 consented to continuation in this 3-year followup study. Mean patient age was 56.1 years and 80% (16) of the study cohort was female. The overall treatment success rate was 75% at 36 months in the per protocol (16) and the intent to treat (20) analyses. In total, 73% of the patients reported improvement in health related quality of life scores above the minimal important difference of 10 points.

CONCLUSIONS

This 3-year followup study using the BlueWind RENOVA iStim system for the treatment of overactive bladder syndrome symptoms confirms the long-term good safety profile with no technical failures reported. Lasting treatment efficacy is mirrored by a sustained positive impact on patient quality of life.

Pain, placebo, and test of treatment efficacy: a narrative review

Over the past decade, the mechanisms underlying placebo effects have begun to be identified. At the same time, the placebo response appears to have increased in pharmacological trials and marked placebo effects are found in neurostimulation and surgical trials, thereby posing the question whether non-pharmacological interventions should be placebo-controlled to a greater extent. In this narrative review we discuss how the knowledge of placebo mechanisms may help to improve placebo control in pharmacological and non-pharmacological trials. We review the psychological, neurobiological, and genetic mechanisms underlying placebo analgesia and outline the current problems and potential solutions to the challenges with placebo control in trials on pharmacological, neurostimulation, and surgical interventions. We particularly focus on how patients' perception of the therapeutic intervention, and their expectations towards treatment efficacy may help develop more precise placebo controls and blinding procedures and account for the contribution of placebo factors to the efficacy of active treatments. Finally, we discuss how systematic investigations into placebo mechanisms across various pain conditions and types of treatment are needed in order to 'personalise' the placebo control to the specific pathophysiology and interventions, which may ultimately lead to identification of more effective treatment for pain patients. In conclusion this review shows that it is important to understand how patients' perception and expectations influence the efficacy of active and placebo treatments in order to improve the test of new treatments. Importantly, this applies not only to assessment of drug efficacy but also to non-pharmacological trials on surgeries and stimulation procedures.

Treatment of Urinary Urgency Incontinence Using a Rechargeable SNM System: 6-Month Results of the ARTISAN-SNM Study

PURPOSE

Sacral neuromodulation is a guideline recommended treatment of urinary dysfunction and fecal incontinence in patients in whom conservative treatments have failed. Historically sacral neuromodulation has been delivered using a nonrechargeable device with an average life span of 4.4 years. Surgery is required to replace the implanted neurostimulator due to battery depletion. Implantation of a long-lived implanted neurostimulator can eliminate the need for replacement surgeries, potentially reducing patient surgical risks and health care costs. The Axonics r-SNM System™ is a miniaturized, rechargeable sacral neuromodulation system designed to deliver therapy for at least 15 years. The ARTISAN-SNM (Axonics® Sacral Neuromodulation System for Urinary Urgency Incontinence Treatment) study is a pivotal study using rechargeable sacral neuromodulation therapy to treat urinary urgency incontinence. Six-month results are presented.

MATERIALS AND METHODS

A total of 129 eligible patients with urinary urgency incontinence were treated. All participants were implanted with a tined lead and the rechargeable sacral neuromodulation system in a nonstaged procedure. Efficacy data were collected using a 3-day bladder diary, the validated ICIQ-OABqol (International Consultation on Incontinence Questionnaire Overactive Bladder quality of life) questionnaire and a participant satisfaction questionnaire. Therapy responders were identified as participants with a 50% or greater reduction in urinary urgency incontinence episodes compared to baseline. We performed an as-treated analysis in all implanted participants.

RESULTS

At 6 months 90% of participants were therapy responders. The mean ± SE number of urinary urgency incontinence episodes per day was reduced from 5.6 ± 0.3 at baseline to 1.3 ± 0.2. Participants experienced a clinically meaningful 34-point improvement on the ICIQ-OABqol questionnaire. There were no serious device related adverse events.

CONCLUSIONS

The Axonics r-SNM System is safe and effective with 90% of participants experiencing clinically and statistically significant improvements in urinary urgency incontinence symptoms.

Effectiveness of Neurostimulation Technologies for the Management of Chronic Pain: A Systematic Review

OBJECTIVES

To describe the state of the literature for clinical effectiveness of neurostimulation used for the management of chronic pain.

METHODS

A systematic review of spinal cord stimulation (SCS), peripheral nerve stimulation (PNS), peripheral nerve field stimulation (PNFS), and supraorbital transcutaneous electrical nerve stimulation in patients with cancer and noncancer chronic pain was conducted. MEDLINE, Embase, CINAHL, and the Cochrane CENTRAL Register of Controlled Trials were searched, using terms like "electrical stimulation therapy" and "pain management." Direction of effect, consistency across studies, and strength of evidence for effects of neurostimulation on chronic pain were narratively synthesized.

RESULTS

A total of 15 randomized controlled trials (RCTs) examining SCS, 7 RCTs examining PNS/PNFS, and 1 nonrandomized trial examining supraorbital transcutaneous electrical nerve stimulation (TENS) were included. In nine SCS studies, neurostimulation had positive effects on pain. In three studies, neurostimulation did not significantly reduce pain. For PNS/PNFS, five studies found improvements in pain offered by neurostimulation; pain outcomes were not reported in two studies. In the TENS study, neurostimulation reduced headaches per month and medication consumption. Overall, 21 studies were of low or unclear risk of bias, 4 were high risk of bias, and the TENS study was not appropriate for assessment using the Cochrane Risk of Bias tool.

CONCLUSIONS

A robust body of evidence examining SCS and PNS was identified. Only one study for PNFS and TENS was identified; both reported pain reductions. Generally, neurostimulation improved pain control. Future studies should examine the effectiveness of neurostimulation offered early in the trajectory of chronic pain.

Specific Changes in Brain Activity during Urgency in Women with Overactive Bladder after Successful Sacral Neuromodulation: A Functional Magnetic Resonance Imaging Study

PURPOSE

The mechanism of sacral neuromodulation is poorly understood. We compared brain activity during urgency before and after sacral neuromodulation in women with overactive bladder and according to the response to treatment.

MATERIALS AND METHODS

Women with refractory overactive bladder who elected sacral neuromodulation were invited to undergo functional magnetic resonance imaging before and after treatment. During imaging the bladder was filled until urgency was experienced. Regions of interest were identified a priori and brain activity in these regions of interest was compared before and after treatment as well as according to the treatment response. Whole brain exploratory analysis with an uncorrected voxel level threshold of p <0.001 was also performed to identify additional brain regions which changed after sacral neuromodulation.

RESULTS

Of the 12 women who underwent a pretreatment functional magnetic resonance imaging examination 7 were successfully treated with sacral neuromodulation and underwent a posttreatment examination. After sacral neuromodulation brain activity decreased in the left anterior cingulate cortex, the bilateral insula, the left dorsolateral prefrontal cortex and the bilateral orbitofrontal cortex (each p <0.05). No new brain regions showed increased activity after sacral neuromodulation. Pretreatment brain activity levels in the bilateral anterior cingulate cortex, the right insula, the bilateral dorsolateral prefrontal cortex, the right orbitofrontal cortex, the right supplementary motor area and the right sensorimotor cortex were higher in women who underwent successful treatment (each p <0.05).

CONCLUSIONS

Brain activity during urgency changes after successful sacral neuromodulation. Sacral neuromodulation may be more effective in women with higher levels of pretreatment brain activity during urgency.

Electrical neuromodulation in the management of lower urinary tract dysfunction: evidence, experience and future prospects

Lower urinary tract dysfunction (LUTD) is common and causes a spectrum of morbidity and decreased quality of life (QoL) for patients. LUTD can range from urinary retention to urge incontinence, and includes a variety of syndromes, with the most common and widely recognized being overactive bladder (OAB). The classic treatments of LUTD and OAB comprise different strategies including behavioral therapies, medications and minimally invasive or invasive surgical procedures. Generally, once patients have tried behavioral modifications and oral medical therapy, and have not experienced adequate relief of their symptoms, the next step is to consider minimally invasive therapies. In the last two decades since FDA approval, sacral nerve stimulation (SNS) has become an accepted intervention, with increasing use and evidence of effectiveness for LUTD, specifically OAB and non-obstructive urinary retention. SNS has shown both objective and subjective improvement in voiding symptoms in several randomized controlled trials (RCTs) when compared to sham or standard medical therapy. The main limitations for more extensive use include relatively high cost, implantation of a device and possibly reoperation secondary to adverse events (AE). Percutaneous tibial nerve stimulation (PTNS) is a less invasive, less direct and less expensive method for neuromodulation, which has also shown effectiveness in several randomized and non-randomized trials, including comparable improvement rates to anticholinergics in OAB management. However, the efficacy of PTNS is only maintained for a short period after the stimulation is delivered. This technique has a much lower rate of AE compared to SNS, but with the inconvenience of weekly visits for stimulation, although implantable devices are on the horizon. In this article we review the mechanism of action, indications, effectiveness and complications related to SNS and PTNS therapy for LUTD.

A Sub-millimeter, Inductively Powered Neural Stimulator

Wireless neural stimulators are being developed to address problems associated with traditional lead-based implants. However, designing wireless stimulators on the sub-millimeter scale (<1 mm³) is challenging. As device size shrinks, it becomes difficult to deliver sufficient wireless power to operate the device. Here, we present a sub-millimeter, inductively powered neural stimulator consisting only of a coil to receive power, a capacitor to tune the resonant frequency of the receiver, and a diode to rectify the radio-frequency signal to produce neural excitation. By replacing any complex receiver circuitry with a simple rectifier, we have reduced the required voltage levels that are needed to operate the device from 0.5 to 1 V (e.g., for CMOS) to ~0.25–0.5 V. This reduced voltage allows the use of smaller receive antennas for power, resulting in a device volume of 0.3–0.5 mm³. The device was encapsulated in epoxy, and successfully passed accelerated lifetime tests in 80°C saline for 2 weeks. We demonstrate a basic proof-of-concept using stimulation with tens of microamps of current delivered to the sciatic nerve in rat to produce a motor response.

Real-Time Changes in Brain Activity during Sacral Neuromodulation for Overactive Bladder

PURPOSE

We performed functional magnetic resonance imaging to identify changes in brain activity during sacral neuromodulation in women with overactive bladder who were responsive to therapy.

MATERIALS AND METHODS

Women recruited into the study had nonneurogenic refractory overactive bladder, responded to sacral neuromodulation and had had a stable program for at least 3 months with no subsequent overactive bladder treatment. Enrolled patients completed validated symptom and quality of life instruments before functional magnetic resonance imaging. Stimulus settings were recorded, devices were switched off for a 5-day washout and instruments were repeated. Three functional magnetic resonance imaging scans with simultaneous sacral neuromodulation stimulation were performed below, at and above stimulus sensory threshold using a block design. This yielded brain activity maps represented by changes in blood oxygenation level dependence. A total of 5 stimulator off and 4 stimulator on cycles of 42 seconds each were imaged. Group analysis was done using a single voxel p value of 0.05 with a false-positive error of 0.05 on cluster analysis.

RESULTS

Six of the 13 patients enrolled completed functional magnetic resonance imaging. Median age was 52 years (range 36 to 64). Urinary symptoms and voiding diary data worsened with washout. Overall brain activation generally progressed with increasing stimulation amplitude. However, activation of the right inferior frontal gyrus remained stable while deactivation of the pons and the periacqueductal gray matter only occurred with subsensory stimulation. Sensory stimulation activated the insula but deactivated the medial and superior parietal lobes. Suprasensory stimulation activated multiple structures and the expected S3 somatosensory region. All devices had normal impedance after functional magnetic resonance imaging.

CONCLUSIONS

Functional magnetic resonance imaging confirmed that sacral neuromodulation influences brain activity in women with overactive bladder who responded to therapy. These changes varied with stimulus intensity.

A New Implanted Posterior Tibial Nerve Stimulator for the Treatment of Overactive Bladder Syndrome: 3-Month Results of a Novel Therapy at a Single Center

PURPOSE

This study was designed to investigate the safety and performance of a new implantable system for tibial nerve stimulation for overactive bladder symptoms.

MATERIALS AND METHODS

A battery-free stimulation device for tibial nerve stimulation (BlueWind Medical, Herzliya, Israel) was implanted in 15 patients. Safety and efficacy assessments were done at 3 months after activation with a 3-day bladder diary, a 24-hour pad test and 2 quality of life questionnaires.

RESULTS

Two males and 13 females were enrolled in the study. Mean age was 54 years (range 19 to 72). Five of 15 patients were previously treated with percutaneous tibial nerve stimulation and 12 experienced urgency urinary incontinence. Median operative time was 34 minutes. At 3 months of followup a significant change was seen in 24-hour frequency from a mean ± SD of 11.8 ± 3.5 to 8.1 ± 2.0 times per day (p = 0.002), the number of severe urinary urgency episodes from 6.5 ± 5.1 to 2.0 ± 2.1 times per day (p = 0.002), the number of severe incontinence episodes from 2.8 ± 5.2 to 0.3 ± 0.4 episodes per day (p = 0.017), urinary loss per day from 243 ± 388 to 39 ± 55 gm (p = 0.038) and improvement in quality of life. After implantation, 3 patients received prolonged antibiotic treatment and 3 received pain medication for 1 week. In 1 patient the device was explanted due to pain and swelling suspicious for infection, although tissue cultures did not reveal a bacterial infection.

CONCLUSIONS

This novel posterior tibial nerve stimulator is safe and easy to implant with good clinical results.

Outcomes of Sacral Neuromodulation in a Privately Insured Population

OBJECTIVE

In this study, we analyzed claims data from the Ingenix data base to analyze outcomes of sacral neuromodulation with respect to both provider and patient factors.

MATERIALS AND METHODS

We used the Ingenix (I3) data base to determine demographic, diagnosis, and procedure success information for years 2002-2007 for privately insured patients. Demographic information was obtained, as were the diagnoses given and procedures performed, based on ICD-9 diagnosis codes and Current Procedural Terminology procedure codes. Multivariate analysis was performed to identify specific predictors of success, as measured by progression to implantation of a pulse generator.

RESULTS

Overall success, as defined by battery placement, was 49.1%. Fifty-one percent of staged procedures were followed by battery placement compared with 24.1% of percutaneous cases (p < 0.0001). Among the patient variables analyzed, women were more likely than men to progress to battery placement. After Stage I testing, patients treated by urologists were overall more likely than gynecologists to proceed to battery placement (I3: 54% vs. 47%, p < 0.0001). Unlike previous findings in other claims-based data sets, we did not observe a provider-volume relationship in the i3 data set.

CONCLUSIONS

Success of sacral neuromodulation, as defined by proceeding to battery placement, was much better after formal staged procedures, which leads us to question the utility of percutaneous techniques. Outcomes were also better among female patients and among those treated by a urologist. Specialty differences will likely diminish over time as more gynecologists adopt sacral neuromodulation.

Inhibition and Excitation of Bladder Function by Tibial Nerve Stimulation Using a Wirelessly Powered Implant: An Acute Study in Anesthetized Cats

PURPOSE

Tibial nerve stimulation is a minimally invasive neuromodulation treatment of overactive bladder. However, in addition to our limited understanding of the underlying mechanisms, there are also questions regarding the long-term delivery of tibial nerve stimulation therapy in patients. We aimed to characterize the effects of stimulation frequency using a wirelessly powered implantable stimulation device.

METHODS AND MATERIALS

Six α-chloralose anesthetized adult male cats were used in this study. A multicontact lead was surgically implanted subcutaneously in the hind limb and used to stimulate the tibial nerve. Using an isovolumetric bladder a short duration of electrical pulses was applied at amplitudes 3 times the motor threshold and at frequencies from 2 to 20 Hz.

RESULTS

Implant driven stimulation of the tibial nerve resulted in frequency dependent activation of bladder reflexes. Low frequency tibial nerve stimulation (2 Hz) consistently evoked excitatory responses (mean ± SE 32.9% ± 3.8%). In contrast, higher frequency tibial nerve stimulation (6 to 20 Hz) inhibited bladder function (overall mean 14.9% ± 2.4%). Although low foot motor thresholds were achieved at initial implantation (mean 0.83 ± 0.05 mA), a notable elevation in threshold amplitude was observed 5 hours after implantation.

CONCLUSIONS

To our knowledge this study provides the first evidence of frequency dependent modulation of bladder function in anesthetized cats. The inhibitory influence of tibial nerve stimulation at frequencies above 6 Hz transitioned to an excitatory effect at 2 Hz. Taken together these preclinical data support the feasibility of using a wirelessly powered implantable device to potentially modulate bladder function in patients.

Neuromodulation in neurogenic bladder

While neuromodulation is a well-established treatment option for patients with non-neurogenic overactive bladder and urinary retention, its applicability to the neurogenic bladder population has only recently been examined more in depth. In this article we will discuss the outcomes, contraindications, and special considerations of sacral and percutaneous tibial nerve stimulation (PTNS) in patients with neurogenic lower urinary tract dysfunction.

Implantable Neurostimulation for Headache Disorders: Effect on Healthcare Utilization and Expenditures

OBJECTIVES

Chronic daily headache is a considerable source of morbidity for patients and also carries an enormous economic burden. Patients who fail standard medication regimens lack well-defined therapies, and neurostimulation is an emerging option for these patients. The purpose of this study was to analyze the cost utility of implantable neurostimulation for treatment of headache.

METHODS

We utilized the Thompson Reuters Marketscan Data base to identify individuals diagnosed with headache disorders who underwent percutaneous neurostimulation. Healthcare expenditures for individuals who subsequently received permanent, surgically implanted neurostimulatory devices were compared to those who did not. Only individuals who sought implantable neurostimulation were included to account for headache severity. The cohorts were adjusted for comorbidity and prior headache-related expenses. Costs were modeled longitudinally using a generalized estimating equation.

RESULTS

A total of 579 patients who underwent percutaneous trial of neurostimulation were included, of which 324 (55.96%) converted to permanent neurostimulation within one year. Unadjusted expenditures were greater for patients who underwent conversion to the permanent neurostimulation device, as expected. Costs grew at a lower rate for patients who converted to permanent device implantation. Cost neutrality for patients receiving the permanent device was reached in less than five years after the enrollment date. The mean cost of conversion to a permanent implantation was $18,607.53 (SD $26,441.34).

CONCLUSIONS

Our study suggests that implantable neurostimulation reduces healthcare expenditures within a relatively short time period in patients with severe refractory headache.

Long-Term Cost-Effectiveness of Upper Airway Stimulation for the Treatment of Obstructive Sleep Apnea: A Model-Based Projection Based on the STAR Trial

STUDY OBJECTIVES

Upper airway stimulation (UAS) is a new approach to treat moderate-to-severe obstructive sleep apnea. Recently, 12-month data from the Stimulation Treatment for Apnea Reduction (STAR) trial were reported, evaluating the effectiveness of UAS in patients intolerant or non-adherent to continuous positive airway pressure therapy. Our objective was to assess the cost-effectiveness of UAS from a U.S. payer perspective.

DESIGN

A 5-state Markov model was used to predict cardiovascular endpoints (myocardial infarction [MI], stroke, hypertension), motor vehicle collisions (MVC), mortality, quality-adjusted life years (QALYs), and costs. We computed 10-year relative event risks and the lifetime incremental cost-effectiveness ratio (ICER) in $/QALY, comparing UAS therapy to no treatment under the assumption that the STAR trial-observed reduction in mean apnea-hypopnea index from 32.0 to 15.3 events/h was maintained. Costs and effects were discounted at 3% per year.

SETTING

U.S. healthcare system; third-party payer perspective.

PARTICIPANTS

83% male cohort with mean age of 54.5 years.

INTERVENTIONS

UAS vs. no treatment.

MEASUREMENTS AND RESULTS

UAS substantially reduced event probabilities over 10 years (relative risks: MI 0.63; stroke 0.75; MVC 0.34), and was projected to add 1.09 QALYs over the patient's lifetime. Costs were estimated to increase by $42,953, resulting in a lifetime ICER of $39,471/QALY.

CONCLUSIONS

Relative to the acknowledged willingness-to-pay threshold of $50,000-$100,000/QALY, our results indicate upper airway stimulation is a cost-effective therapy in the U.S. healthcare system.

Sudden loss of the deep brain stimulation effect with high impedance without macroscopic fracture: a case report and review of the published literature

The number of deep brain stimulation (DBS) hardware complications has increased during the past decade. In cases of abnormally high lead impedance with no evidence of a macroscopic fracture, optimal treatment options have not yet been established. Here, we present the case of a 49-year-old woman with a 12-year history of Parkinson's disease who received bilateral subthalamic nucleus DBS in March 2006. The patient showed good control of parkinsonism until December 24, 2010, when she awoke with abrupt worsening of parkinsonian symptoms. At telemetric testing, lead impedances were found at >2,000 Ω in all four leads on the left side. Fracture of a lead or an extension wire was suspected. However, radiological screening and palpation revealed no macroscopic fracture. In June 2011, the implantable pulse generator (IPG) was changed under local anesthesia without any complications. Postoperatively, her parkinsonism immediately improved to the previous level, and the lead impedance readings by telemetry were also normalized. The disconnection of the neurostimulator connector block and the hybrid circuit board of the IPG was confirmed by destructive analysis. The present report illustrates that a staged approach that starts with simple IPG replacement can be an option for some cases of acute DBS effect loss with high impedance, when radiological findings are normal, thereby sparing the intact electrodes and extension wires.