Sacral nerve stimulation for the treatment of refractory voiding and bowel dysfunction

Regulation of enteric nervous system via sacral nerve stimulation in opioid-induced constipated rats

Objectives

Sacral nerve stimulation (SNS) has been employed for treating constipation. However, its mechanisms involving enteric nervous system (ENS) and motility are largely unknown. In this study, we investigated the possible ENS involvement of SNS in treating Loperamide-induced constipation in rats.

Methods

Experiment-1 was designed to study the effects of acute SNS on whole colon transit time (CTT). In experiment-2, we induced constipation by Loperamide and then applied daily SNS or sham-SNS for 1 week. Choline acetyltransferase (ChAT), nitric oxide synthase (nNOS), and PGP9.5 in colon tissue were examined at the end of the study. Moreover, survival factors such as phosphorylated AKT (p-AKT) and Glial cell-derived neurotrophic factor (GDNF) were measures by immunohistochemistry (IHC) and western blot (WB).

Key results

(1) SNS with one set of parameters shortened CTT starting at 90 min after phenol red administration (p < 0.05). (2) While Loperamide induced slow transit constipation with a significant reduction in fecal pellet number and feces wet weight, daily SNS for a week resolved constipation. (3) Moreover, SNS was able to shorten whole gut transit time comparing to sham-SNS (p = 0.01). (4) Loperamide reduced the number of PGP9.5 and ChAT positive cells, and downregulated ChAT protein expression and upregulated nNOS protein expression, whereas these detrimental effects were significantly reversed by SNS. (5) Furthermore, SNS increased expressions of both GDNF and p-AKT in colon tissue. (6) Vagal activity was reduced following Loperamide (p < 0.01); yet SNS normalized vagal activity.

Conclusion

SNS with appropriate parameters improves opioid-induced constipation and reversed the detrimental effects of Loperamide on enteric neurons possibly via the GDNF-PI3K/Akt pathway.GRAPHICAL ABSTRACT.

Perioperative and anesthetic considerations for the management of neuromodulation systems

The use of neuromodulation systems is increasing for the treatment of various pathologies ranging from movement disorders to urinary incontinence to chronic pain syndromes. While the type of neuromodulation devices varies, they are largely categorized as intracranial (eg, deep brain stimulation), neuraxial (eg, spinal cord stimulation, dorsal root ganglion stimulation, and intrathecal drug delivery systems), or peripheral (eg, sacral nerve stimulation and peripheral nerve stimulation) systems. Given the increasing prevalence of these systems in the overall population, it is important for anesthesiologists, surgeons, and the perioperative healthcare team to familiarize themselves with these systems and their unique perioperative considerations. In this review, we explore and highlight the various neuromodulation systems, their general perioperative considerations, and notable special circumstances for perioperative management.

Cost-effectiveness of overactive bladder treatments from a US commercial and payer perspective

Aim: The cost-effectiveness of treatment options (anticholinergics, β3-adrenoceptor agonists, onabotulinumtoxinA, sacral nerve stimulation and percutaneous tibial stimulation [the latter two including new rechargeable neurostimulators]) for the management of overactive bladder (OAB) were compared with best supportive care (BSC) using a previously published Markov model. Materials & methods: Cost-effectiveness was evaluated over a 15-year time horizon, and sensitivity analyses were performed using 2- and 5-year horizons. Discontinuation rates, resource utilization, and costs were derived from published sources. Results: Using Medicare and commercial costs over a 15-year time period, onabotulinumtoxinA 100U had incremental cost-effectiveness ratios (ICERs) gained of $39,591/quality-adjusted life-year (QALY) and $42,255/QALY, respectively, versus BSC, which were the lowest ICERs of all assessed treatments. The sensitivity analyses at 2- and 5-year horizons also showed onabotulinumtoxinA to be the most cost-effective of all assessed treatments versus BSC. Conclusion: OnabotulinumtoxinA 100U is currently the most cost-effective treatment for OAB.

A New Medical Device Modeling Framework for Predicting the Performance of Indwelling Continence Care Devices and Improving Patient Care

A computational model of the human torso has been developed to study the stability of implanted leads that are part of a sacral nerve stimulation system. The model was built using presegmented anatomies that were themselves built from imaging of human patients. The sacral leads are represented using beam elements, and their interaction with the tissue is defined using a function that relates frictional force to the amount of slip between the lead and tissue. Displacements to the skin in the sacral region are applied to simulate activities of daily living, and the resulting displacement of the tip of the lead is indicative of its tendency to dislodge in real patients. Validation of the model was performed using experimental results collected in human cadavers. In these experiments, analogous displacements of the skin were applied after implantation of the leads per normal implant procedures. The displacement of the distal tip of the lead was measured using computed tomography (CT) imaging, allowing direct comparison to the predictions of the model. Recognizing that many model inputs were informed by sparse literature values, a novel application of uncertainty quantification methodology was developed wherein all model inputs were treated as uncertain intervals. This allowed an optimization approach to be used for estimating the uncertain interval for the model outputs. The computational model and cadaver results were used to study the performance of a new sacral lead design, relative to a predicate product. The results showed that the reduction in lead axial stiffness in the new design leads to less lead tip displacement, such that the lead is more likely to remain near the therapeutic target in patients.

The Impact of Fluoroscopy During Percutaneous Nerve Evaluation on Subsequent Implantation of a Sacral Neuromodulator Among Women With Pelvic Floor Disorders: A Randomized, Noninferiority Trial

OBJECTIVES

To evaluate whether percutaneous nerve evaluation (PNE) without fluoroscopy is inferior to fluoroscopy use in women undergoing trials of sacral neuromodulation (SNM) for pelvic floor disorders (PFDs).

MATERIALS AND METHODS

In an unblinded noninferiority trial, women undergoing PNE were randomized to fluoroscopy or no fluoroscopy. The primary outcome was "success" and defined as implantation of the permanent SNM device within three months of PNE. At an expected 40% success and a 30% noninferiority threshold, 33 participants in each group were needed for 80% power (α = 0.05). Univariate analyses and a logistic regression model adjusting for univariate variables associated with the primary outcome were performed.

RESULTS

From April 2016 to December 2018, 74 participants underwent PNE of which 36 underwent PNE with fluoroscopy and 38 without. The fluoroscopy group had less baseline mean daily voids compared to the no fluoroscopy group (10.79 ± 6.48 vs. 16.21 ± 10.05, p = 0.01). PNE performed without fluoroscopy had similar success (18/38, 47.4%) compared to fluoroscopy (21/36, 58.3%), meeting our noninferiority definition (difference 10.9%, 90% CI -8% to 30%, p = 0.049). In a logistic regression model adjusting for age, Charlson comorbidity index, stage of prolapse, and number of baseline voids per day, trial success was still similar between the two groups (adjOR 1.82, 95% CI 0.52 to 6.94, p = 0.36).

CONCLUSIONS

PNE performed without fluoroscopy is noninferior to PNE with fluoroscopy use for the outcome of SNM device implantation within three months among women undergoing therapy for PFDs.

Timing of sacral neurostimulation is important for increasing bladder capacity in the anesthetized rat

We assessed the effects of limited application of sacral neurostimulation (SNS) during bladder filling on bladder capacity using our previously published SNS model in rats. Female Sprague-Dawley rats (n = 24) were urethane anesthetized (1.2 g/kg sc) and implanted with jugular venous and transvesical bladder catheters. L6/S1 nerve trunks were isolated bilaterally, and two electrodes were placed on each exposed nerve. True bladder capacity (TBC) was determined using stable single-fill cystometrograms. In the first series of experiments, SNS was applied at the onset of bladder filling for 25%, 50%, 75%, and 100% of the previous control filling cycle duration (n = 10). In the second series of experiments, SNS was applied during the first, second, third, and fourth 25% and the first and second 50% of the control fill. In the first series, a significant increase in TBC was observed only when SNS was applied for 75% or 100% of the control fill duration (30% and 35%, respectively, P < 0.05). In the second series, significant increases in TBC only occurred during the fourth 25% period and second 50% period (32% and 43%, respectively, P < 0.001). Results from the second series also revealed an increase in subsequent single-fill bladder capacities (TBC) only when SNS was applied during the second 50% of the prior fill cycle. These data indicate that the application of SNS during the final 50% of the bladder fill cycle is necessary and sufficient for increasing bladder capacity.

Sacral nerve stimulation with appropriate parameters improves constipation in rats by enhancing colon motility mediated via the autonomic-cholinergic mechanisms

Although sacral nerve stimulation (SNS) has been applied for treating constipation, its parameters were adopted from SNS for fecal incontinence, its effects are limited, and mechanisms are largely unknown. We investigated the effects and mechanism of SNS with appropriate parameters on constipation in rats treated with loperamide. First, using rectal compliance as an outcome measure, an experiment was performed to derive effective SNS parameters. Then, a 7-day SNS was performed in rats with constipation induced by loperamide. Autonomic functions were assessed by spectral analysis of heart rate variability (HRV) derived from an electrocardiogram. Serum levels of pancreatic polypeptide (PP), norepinephrine (NE), and acetylcholine (ACh) in colon were assessed. 1) Acute SNS at 5 Hz, 100 µs was found effective in enhancing rectal compliance and accelerating distal colon transit (P < 0.05 vs. sham SNS). 2) The 7-day SNS normalized loperamide-induced constipation, assessed by the number, weight, and water content of fecal pellets, and accelerated the distal colon transit (29.4 ± 3.7 min with sham SNS vs. 16.4 ± 5.3 min with SNS but not gastric emptying or intestinal transit. 3) SNS significantly increased vagal activity (P = 0.035) and decreased sympathetic activity (P = 0.012), assessed by spectral analysis of HRV as well as by the serum PP. 4) SNS increased ACh in the colon tissue; atropine blocked the accelerative effect of SNS on distal colon transit. We concluded that SNS with appropriate parameters improves constipation induced by loperamide by accelerating distal colon motility, mediated via the autonomic-cholinergic function.NEW & NOTEWORTHY Although sacral nerve stimulation (SNS) has been applied for treating constipation, its parameters were adopted from SNS for fecal incontinence, effects are limited, and mechanisms are largely unknown. This paper shows that SNS with appropriate parameters improves constipation induced by loperamide by accelerating distal colon motility mediated via the autonomic-cholinergic function.

Neuromodulation - a therapeutic option for refractory overactive bladder. A recent literature review

Overactive bladder (OAB) affects approximately 17% of the population. The treatment of this clinical condition is challenging, especially when conservative therapy is not effective. There are limited options for the treatment of recurrent OAB. Neuromodulation has taken a significant place in the therapy of recalcitrant lower urinary tract dysfunctions over the past 20 years. The aim of this study was to review the literature evaluating the different forms of neuromodulation in various urological clinical conditions and to show the future prospects of this treatment method. Further studies are necessary to determine the effectiveness of neuromodulation and to identify the prognostic factors of therapeutic success. This could be helpful in the selection of patients who will be most likely to respond positively to the treatment.

Broken Sacral Neuromodulation Lead Migration Into the Sigmoid Colon: A Case Report

Sacral neuromodulation is an effective treatment of urinary incontinence, fecal incontinence, and idiopathic urinary retention. The procedure is considered low risk with overall low complication rates. This report describes a 40-year-old woman who underwent sacral neuromodulation explant and full-system implant for weaning efficacy of her device. During device removal, the tined lead broke and was left in situ. Four months later, she was diagnosed as having a wound infection at the site of the retained lead. Imaging revealed lead fragment migration into the sigmoid colon. A colocutaneous fistula was noted soon thereafter. The retained lead was removed during a colonoscopy and the fistula healed. A retained lead can result in migration through the peritoneum and into the colon. This can be managed with assistance from colorectal or gastroenterology consultants.

Cost–effectiveness of overactive bladder treatments: from the US payer perspective

Aim: To assess the cost–effectiveness of onabotulinumtoxinA (onabotA), implantable sacral nerve stimulation devices, percutaneous tibial nerve stimulation, anticholinergic medications and mirabegron compared with best supportive care (BSC) for management of refractory overactive bladder (OAB). Methods: A Markov model was developed to compare the cost–effectiveness of treatment options with BSC over a 10-year time horizon. Resource utilization, discontinuation rates and costs were derived from unpublished and published sources. Quality-adjusted life-years (QALYs) and incremental cost–effectiveness ratios were reported. Results: Treatment with onabotA 100U produced the largest gain in QALYs (7.179) and lowest estimated incremental cost–effectiveness ratio ($32,680/QALY) of all assessed treatments compared with BSC. Conclusion: Compared with BSC, onabotA 100U was the most cost-effective treatment option for patients with refractory OAB.

Risk factors for explantation due to infection after sacral neuromodulation: a multicenter retrospective case-control study

BACKGROUND

Sacral neuromodulation is an effective therapy for overactive bladder, urinary retention, and fecal incontinence. Infection after sacral neurostimulation is costly and burdensome. Determining optimal perioperative management strategies to reduce the risk of infection is important to reduce this burden.

OBJECTIVE

We sought to identify risk factors associated with sacral neurostimulator infection requiring explantation, to estimate the incidence of infection requiring explantation, and identify associated microbial pathogens.

STUDY DESIGN

This is a multicenter retrospective case-control study of sacral neuromodulation procedures completed from Jan. 1, 2004, through Dec. 31, 2014. We identified all sacral neuromodulation implantable pulse generator implants as well as explants due to infection at 8 participating institutions. Cases were patients who required implantable pulse generator explantation for infection during the review period. Cases were included if age ≥18 years old, follow-up data were available ≥30 days after implantable pulse generator implant, and the implant was performed at the institution performing the explant. Two controls were matched to each case. These controls were the patients who had an implantable pulse generator implanted by the same surgeon immediately preceding and immediately following the identified case who met inclusion criteria. Controls were included if age ≥18 years old, no infection after implantable pulse generator implant, follow-up data were available ≥180 days after implant, and no explant for any reason <180 days from implant. Controls may have had an explant for reasons other than infection at >180 days after implant. Fisher exact test (for categorical variables) and Student t test (for continuous variables) were used to test the strength of the association between infection and patient and surgery characteristics. Significant variables were then considered in a multivariable logistic regression model to determine risk factors independently associated with infection.

RESULTS

Over a 10-year period at 8 academic institutions, 1930 sacral neuromodulator implants were performed by 17 surgeons. In all, 38 cases requiring device explant for infection and 72 corresponding controls were identified. The incidence of infection requiring explant was 1.97%. Hematoma formation (13% cases, 0% controls; P = .004) and pocket depth of ≥3 cm (21% cases, 0% controls; P = .031) were independently associated with an increased risk of infection requiring explant. On multivariable regression analysis controlling for significant variables, both hematoma formation (P = .006) and pocket depth ≥3 cm (P = .020, odds ratio 3.26; 95% confidence interval, 1.20-8.89) remained significantly associated with infection requiring explant. Of the 38 cases requiring explant, 32 had cultures collected and 24 had positive cultures. All 5 cases with a hematoma had a positive culture (100%). Of the 4 cases with a pocket depth ≥3 cm, 2 had positive cultures, 1 had negative cultures, and 1 had a missing culture result. The most common organism identified was methicillin-resistant Staphylococcus aureus (38%).

CONCLUSION

Infection after sacral neuromodulation requiring device explant is low. The most common infectious pathogen identified was methicillin-resistant S aureus. Demographic and health characteristics did not predict risk of explant due to infection, however, having a postoperative hematoma or a deep pocket ≥3 cm significantly increased the risk of explant due to infection. These findings highlight the importance of meticulous hemostasis as well as ensuring the pocket depth is <3 cm at the time of device implant.

Predictors of outcome in children and adolescents with overactive bladder treated with parasacral transcutaneous electrical nerve stimulation

BACKGROUND

Parasacral transcutaneous electrical nerve stimulation (TENS) has emerged as an effective treatment for overactive bladder (OAB) in view of its high success rates in improving lower urinary tract symptoms and constipation, with no direct side effects. However, the clinical characteristics associated with the outcomes remain to be established.

OBJECTIVE

The aim of this study was to evaluate potential predictors of outcome in children with OAB treated using parasacral TENS.

STUDY DESIGN

This was a prospective study of children with symptoms of isolated OAB, enrolled consecutively to the study and treated with parasacral TENS (figure). Isolated OAB was defined as the presence of urinary urgency with no signs of dysfunctional voiding. The symptoms were considered completely resolved when a patient's parents/guardians or the patients themselves reported a 100% improvement. Parasacral TENS was performed twice weekly for a total of 20 sessions of 20 min each at 10 Hz. The potential predictive factors evaluated were: sex, age, daytime incontinence, nocturia, a prior history of urinary tract infection, the presence of nocturnal enuresis, constipation and holding maneuvers.

RESULTS

Eighty-three patients with a mean age of 7.8 ± 2.8 years were included in the study. Complete resolution of symptoms was achieved in 47 (56.6%). Following parasacral TENS treatment, a significant response was reported in 96.4% of cases. Of the 55 patients with nocturnal enuresis, partial resolution was achieved in 30 cases (54.5%), with a statistically significant association between nocturnal enuresis and the patient's response to treatment (p < 0.004; OR = 4.4, 95% CI 1.5-12.5). No other factor was associated with response to treatment.

DISCUSSION

To the best of our knowledge, this association between nocturnal enuresis and failure to respond to parasacral TENS treatment for lower urinary tract dysfunction has not previously been reported. The identification of factors capable of predicting therapeutic failure may allow professionals to select those specific patients who would benefit from a multimodal approach in the treatment of this pathology, which has such a significant impact on the quality of life of affected patients.

CONCLUSIONS

Nocturnal enuresis was the only symptom associated with a poor outcome following parasacral TENS treatment in children with OAB.

Trends in Surgeon-Level Utilization of Sacral Nerve Stimulator Implantation for Fecal Incontinence in New York State

BACKGROUND

There is a paucity of real-world data regarding surgeon utilization of sacral nerve stimulation for fecal incontinence compared with anal sphincteroplasty.

OBJECTIVE

This study aims to examine trends in sacral nerve stimulation use compared with sphincteroplasty for fecal incontinence and surgeon-level variation in progression to implantation of the pulse generator.

DESIGN

This is a population-based study.

PATIENTS

Patients with fecal incontinence between 2011 and 2014 in New York who underwent stage 1 of the sacral nerve stimulation procedure were selected. For the comparison with sphincteroplasty, patients with fecal incontinence who underwent anal sphincteroplasty between 2008 and 2014 were included.

MAIN OUTCOME MEASURES

The main outcomes after sacral nerve stimulation generator placement were unplanned 30-day admission, emergency department visit within 30 days, revision or explant of leads or generator, and 30-day mortality.

RESULTS

Six hundred twenty-one patients with fecal incontinence underwent a stage 1 procedure with 79.7% progressing to stage 2. There has been an increase in the number of sacral nerve stimulation cases per year as well as the number of surgeons performing the procedure. The rate of progression to stage 2 among patients treated by colorectal surgeons was 80.2% compared with 77.0% among those treated by noncolorectal surgeons. Among those who completed stage 2, there were 3 (0.5%) unplanned 30-day admissions, 24 (4.4%) emergency department visits within 30 days, and 0 mortalities within 30 days. Thirty-two (6.5%) patients had their leads or pulse generator revised or explanted. There was a significant decrease in annual sphincteroplasty cases and the number of providers performing the procedure starting in 2011.

LIMITATIONS

We lacked data regarding patient and physician decision making and the severity of disease.

CONCLUSIONS

Sacral nerve stimulation for fecal incontinence is increasing in popularity with an increasing number of surgeons utilizing sacral nerve stimulation for fecal incontinence rather than sphincteroplasty. See Video Abstract at http://links.lww.com/DCR/A450.

Radiographic Position of the Electrode as a Predictor of the Outcome of InterStim Therapy

Purpose

Sacral neuromodulation (SNM) therapy is indicated for some refractory urological conditions. The electrode lead position in sacral x-rays during routine follow-up may predict the outcome of SNM therapy. To determine whether the radiographic position of the electrode in the sacral foramen predicted the long-term outcome of SNM therapy.

Methods

This was a retrospective study of patients who underwent InterStim SNM at Toronto Western Hospital by 2 surgeons from July 2013 to March 2014. The position of electrodes in relation to the sacral bone was assessed on follow-up sacral x-rays. In the lateral view, we determined the location of the radio-opaque marker of the electrode relative to the inner surface of the sacrum (P3, D3, P2, D2, P1, D1, P0, and D0). In the anteroposterior view, the angle between a line through the spinous process shadow and the electrode was measured (0°–30°, 30°–60°, 60°–90°, >90°, or medial). Dissatisfied patients were defined as those who did not improve based on a voiding diary or those who needed salvage treatment after SNM. The primary endpoint was to determine whether the electrode lead position on sacral x-rays predicted the outcome of SNM therapy.

Results

A total of 69 patients (61 female and 8 male patients) were included, with a median age of 55 years. Forty-two of the patients (60.9%) had refractory overactive bladder, 21 (30.4%) suffered from chronic urinary retention, and 6 (8.7%) had lower urinary tract symptoms and chronic pelvic pain syndrome. The univariate analysis did not show any correlation between SNM response and the electrode position or angle. Dummy regression analysis using response to implantation as the dependent outcome variable did not show any significance for any of the predictors.

Conclusions

Our study did not show a correlation between the long-term response to SNM and the electrode position on follow-up sacral x-rays. In this study, electrode lead position in sacral x-ray at follow-up was not correlated with the outcome of SNM therapy.

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.

Electrical stimulation for the treatment of obstructive sleep apnoea: a review of the evidence

INTRODUCTION

Obstructive sleep apnoea is an increasingly prevalent clinical condition with significant impact on individuals and public health. Continuous positive airway pressure therapy is the standard treatment, but adherence is limited and alternative treatments are needed. In this context, non-invasive and invasive methods for the electrical stimulation of upper airway dilator muscles have been demonstrated to be effective in selected patients. Areas covered: This review will cover investigations on the clinical effects, safety, and tolerability of non-invasive and invasive electrical stimulation of the upper airway for the management of obstructive sleep apnoea. Following a search of the relevant literature published on PubMed this review is focused mainly on data obtained from randomized clinical trials and clinical studies. Expert commentary: The available evidence provides a rationale to consider upper airway electrical stimulation as treatment for selected patients with obstructive sleep apnoea, who have poor adherence or experience difficulties with continuous positive airway pressure therapy. Non-invasive stimulation using transcutaneous electrodes and implantable hypoglossal nerve stimulator technologies may provide an alternative to continuous positive airway pressure for the treatment of obstructive sleep apnoea via restoration of neuromuscular tone and improved upper airway patency.

Evaluation of the axonics modulation technologies sacral neuromodulation system for the treatment of urinary and fecal dysfunction

INTRODUCTION

Sacral neuromodulation (SNM) remains one of the few effective treatments for refractory bladder and bowel dysfunction. However, SNM is associated with frequent need for surgical intervention, in many cases because of a failed battery. A rechargeable SNM system, with a manufacturer-reported battery life of 15 years or more, has entered post-market clinical testing in Europe but has not yet been approved for clinical testing in the United States. Areas covered: We review existing neuromodulation technologies for the treatment of lower urinary tract and bowel dysfunction and explore the limitations of available technology. In addition, we discuss implantation technique and device specifications and programming of the rechargeable SNM system in detail. Lastly, we present existing evidence for the use of SNM in bladder and bowel dysfunction and evaluate the anticipated trajectory of neuromodulation technologies over the next five years. Expert commentary: A rechargeable system for SNM is a welcome technological advance. However surgical revision not related to battery changes is not uncommon. Therefore, while a rechargeable system would be expected to reduce costs, it will not eliminate the ongoing maintenance associated with neuromodulation. No matter the apparent benefits, all new technologies require extensive post-market monitoring to ensure safety and efficacy.

Sacral Neuromodulation in Urological Practice

Sacral neuromodulation (SNM) is a minimally invasive, restorative treatment to improve voiding and elimination functions. We give a historical perspective of SNM and explore the evidence for the use of this therapy for Food and Drug Administration-approved pathologies as well as disease processes that are being treated internationally. Ensuring optimal lead placement increases the potential of a comfortable, durable, and efficacious response. The future of SNM aims to maximize its potential benefit, refine its use, and minimize its risks and cost. Evolution of the therapy includes better device options, better software for patient and clinician use, more programming capabilities, and new nerve targets.

Chronic pudendal neuromodulation using an implantable microstimulator improves voiding function in diabetic rats

Objective

Few studies have investigated the feasibility of using chronic pudendal neuromodulation for improving voiding function in patients with diabetes who are also experiencing urinary retention. The present study investigated the effects of chronic electrical stimulation (ES) of the sensory branch of the pudendal nerve on voiding function in diabetic rats.

Approach

A custom-made implantable microstimulation system was designed and manufactured for chronic implantation in normal control (NC) and diabetic rats. After three or six weeks of pudendal neuromodulation, the intravesical pressure, external urethral sphincter electromyograms (EUS-EMGs), and urine flow rate (UFR) of all rats were simultaneously recorded to assess the effects of chronic pudendal ES on voiding function. Morphological changes in pudendal axons were assessed through hematoxylin and eosin (H&E) staining.

Significance

This study demonstrated the feasibility of using chronic pudendal neuromodulation for improving voiding function in diabetic rats. These results may facilitate the development of an advanced neural prosthesis for restoring bladder function in clinical settings.

Preclinical assessment of potential interactions between botulinum toxin and neuromodulation for bladder micturition reflex

BACKGROUND

While botulinum toxin A (BoNT-A) has become a more commonly used second-line treatment for patients with detrusor overactivity, it remains unknown whether the impacts of this therapy may persist to influence other therapies such as sacral neuromodulation. In this preclinical study we have evaluated urodynamic functions to intradetrusor injection of BoNT-A and the bladder inhibitory effects of spinal nerve stimulation (SNS) following BoNT-A treatment.

METHODS

Female rats were anesthetized with 3 % isoflurane. BoNT-A (2 units, 0.2 ml) or saline were injected into the detrusor. Rats then were housed for 2 days to 1 month before neuromodulation study. Monopolar electrodes were placed under each of the L6 spinal nerve bilaterally under urethane anesthesia. A bladder cannula was inserted via the urethra for saline infusion and intravesical pressure recording.

RESULTS

Intradetrusor injection of BoNT-A for 1-2 weeks or 1 month significantly increased bladder capacity compared with saline injection (p < 0.05, two-way ANOVA). Following BoNT-A, SNS attenuated the frequency of bladder contractions, either eliminating bladder contractions or reducing the contraction frequency during electrical stimulation. Inhibition of the contraction frequency by SNS following BoNT-A treated rats was not different from that measured following saline injection.

CONCLUSIONS

BoNT-A increased the bladder capacity, but compensating for additional saline infusion to the enlarged urinary bladder in BoNT-A pretreated rats, the bladder contractions induced by bladder filling were attenuated by SNS. BoNT-A did not alter the ability of SNS to inhibit bladder contraction following intradetrusor injection of BoNT-A for 2 days, 1-2 weeks or 1 month. These results support further pre-clinical and clinical studies to evaluate potential interactions or combination therapy with neuromodulation and intradetrusor BoNT-A therapeutic approaches.

Upper Airway Stimulation for Obstructive Sleep Apnea: Past, Present, and Future

ABSTRACT

Obstructive sleep apnea (OSA) is an increasingly prevalent clinical problem with significant effects on both personal and public health. Continuous positive airway pressure (CPAP) has demonstrated excellent efficacy and low morbidity; long-term adherence rates approach 50%. Although traditional upper airway surgical procedures target the anatomic component of obstruction, upper airway stimulation tackles the twin goals of improving anatomic and neuromuscular pathology. After decades of trials demonstrating proof of concept of hypoglossal nerve stimulation in animal and human subjects, the results of a large multicenter, prospective trial were recently published. The trial demonstrated that hypoglossal nerve stimulation led to significant improvements in objective and subjective measurements of the severity of OSA. This novel approach is the first to combine sleep surgery techniques with a titratable medical device for the treatment of OSA. Further research is required to define optimal patient selection and device performance and to demonstrate long-term effectiveness.

Physician Use of Sacral Neuromodulation Among Medicare Beneficiaries With Overactive Bladder and Urinary Retention

OBJECTIVE

To identify physician-level factors associated with high rates of sacral neuromodulation testing.

MATERIALS AND METHODS

We performed a retrospective cohort study using a 20% sample of national Medicare claims to identify physicians who performed sacral neuromodulation procedures between 2005 and 2010. Physician-level rates of device testing were determined based on the number of patients seen for overactive bladder and urinary retention diagnoses in the office in each calendar year. These rates were then used to fit a Poisson model to examine factors associated with high rates of device testing.

RESULTS

The number of physicians performing test procedures increased 4-fold from 2005 to 2010. Average rates of test procedures increased from 4.0 to 6.4 procedures per physician per year (P <.001), whereas rates of device implantation remained stable (P = .23). Physicians who had higher rates of device testing were associated with lower rates of device implantation (estimate, -1.76, P <.01). Other predictors of physicians with higher test rates included more recent calendar year, testing done in any setting other than an ambulatory surgery center, gynecology subspecialty, and geographic location in the South and West (all P values <.01).

CONCLUSION

Over time, physicians are testing more patients but are not implanting more devices. Additionally, there is an inverse relationship between rates of device testing and implantation, suggesting opportunities to improve efficiency and resource utilization.

Effective treatment of dyssynergic defecation using sacral neuromodulation in a patient with cerebral palsy

BACKGROUND

Dyssynergic defecation is a complex bowel problem that leads to chronic constipation and abdominal pain. Management is often challenging owing to the incoordination of multiple pelvic floor muscles involved in normal defecation.

CASE

We report a case of dyssynergic defecatory dysfunction in a patient with cerebral palsy treated with sacral neuromodulation. At presentation, Sitz marker study and magnetic resonance defecography showed evidence of chronic functional constipation. Anorectal manometry, rectal anal inhibitory reflex, and rectal sensation study showed intact reflex and decreased first sensation of lower canal at 50 mL. After stage 2 of InterStim implant placement, bowel habits improved to once- to twice-daily soft solid bowel movements from no regular solid bowel movements. Fecal incontinence improved from daily liquid and small solid loss to no stool leakage.

CONCLUSIONS

In patients with systemic medical problems contributing to defecatory dysfunction and bowel incontinence, such as cerebral palsy, sacral neuromodulation was found to provide significant relief of bowel symptoms in addition to associated abdominal pain. As a result of intervention, the patient reported significant improvement in quality of life and less limitations due to dyssynergic defecation.

Active sacral neuromodulator during pregnancy: a unique case report

Sacral neuromodulation with an implanted device is used in patients who experience urinary retention and malfunctioning overactive bladder where conservative treatment is not sufficient. The knowledge of its effect on pregnancy is not known. This article presents the case of a 34-year-old pregnant woman with an implanted device, the use of which was not discontinued during her pregnancy. Full-term pregnancy was achieved, and a healthy child was delivered by cesarean section. Sacral neuromodulation during pregnancy appears to be safe and may be preferable to intermittent bladder catheterizations that increase the chance of urinary infections.