How does neuromodulation work

Considerations and discussions on the clear definition and definite scope of brain-computer interfaces

Brain-computer interface (BCI) is a revolutionizing human-computer interaction with potential applications in both medical and non-medical fields, emerging as a cutting-edge and trending research direction. Increasing numbers of groups are engaging in BCI research and development. However, in recent years, there has been some confusion regarding BCI, including misleading and hyped propaganda about BCI, and even non-BCI technologies being labeled as BCI. Therefore, a clear definition and a definite scope for BCI are thoroughly considered and discussed in the paper, based on the existing definitions of BCI, including the six key or essential components of BCI. In the review, different from previous definitions of BCI, BCI paradigms and neural coding are explicitly included in the clear definition of BCI provided, and the BCI user (the brain) is clearly identified as a key component of the BCI system. Different people may have different viewpoints on the definition and scope of BCI, as well as some related issues, which are discussed in the article. This review argues that a clear definition and definite scope of BCI will benefit future research and commercial applications. It is hoped that this review will reduce some of the confusion surrounding BCI and promote sustainable development in this field.

Sacral neuromodulation for constipation and fecal incontinence in children and adolescents - study protocol of a prospective, randomized trial on the application of invasive vs. non-invasive technique

BACKGROUND

A therapeutic effect of sacral neuromodulation (SNM) on fecal incontinence (FI) and quality of life has been proven in adults. SNM is, however, rarely used in pediatric cases. The aim of the study is to investigate effects of SNM in pediatric constipation in a prospective parallel-group trial.

METHODS

A monocentric, randomized, unblinded, parallel-group trial is conducted. SNM is conducted in the invasive variant and in an innovative, external approach with adhesive electrodes (enteral neuromodulation, ENM). We include patients with constipation according to the ROME IV criteria and refractory to conventional options. Patients with functional constipation and Hirschsprung's disease are able to participate. Participants are allocated in a 1:1 ratio to either SNM or ENM group. Clinical data and quality of life is evaluated in regular check-ups. Neuromodulation is applied continuously for 3 months (end point of the study) with follow-up-points at 6 and 12 months. Findings are analyzed statistically considering a 5% significance level (p ≤ 0.05). Outcome variables are defined as change in (1) episodes of abdominal pain, (2) episodes of FI, (3) defecation frequency, (4) stool consistency. Improvement of proprioception, influence on urinary incontinence, quality of life and safety of treatment are assessed as secondary outcome variables. We expect a relevant improvement in both study groups.

DISCUSSION

This is the first trial, evaluating effects of neuromodulation for constipation in children and adolescents and comparing effects of the invasive and non-invasive application (SNM vs. ENM).

TRIAL REGISTRATION

The study is registered with clinicaltrials.gov, Identifier NCT04713085 (date of registration 01/14/2021).

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Effects of percutaneous neuromodulation in neuromusculoskeletal pathologies: A systematic review

BACKGROUND

Percutaneous neuromodulation (PNM) consists in using electrical stimulation on a peripheral nerve by using a needle as an electrode in order to lessen the pain and restore both neuromuscular and nervous system functions. The aims of the present study were to evaluate the current scientific evidence of the effects of PNM on pain and physical capabilities in neuromusculoskeletal injuries.

METHODS

Data sources: There was used the PRISMA protocol. In order to do the literature research, there were used the PubMed, Cochrane, Scopus, and Web of Science databases. Study selection or eligibility criteria: There were also included experimental clinical trials published between 2010 and nowadays, tested on humans, which feature treatment based on needles with electrical stimulation in order to treat neuromusculoskeletal injuries. Study appraisal and synthesis methods: A quality assessment was performed according to the PEDro scale and reviewed the impact factor and quartile of the journal.

RESULTS

The treatment resulted in significant improvement in terms of pain intensity, pressure pain threshold, balance, muscular endurance, functionality/disability, subjective improvement, function of the descending pain modulatory system, and intake of drugs. Limitations: the lack of previous research studies on the subject and the lack of data on opioid intake in the selected studies.

CONCLUSION

Treatment based on PNM may be an alternative when treating injuries in soft tissues without significant side effects. However, there are few articles investigating the effects of PNM so more evidence is needed to draw solid conclusions.

Noninvasive spinal neuromodulation mitigates symptoms of idiopathic overactive bladder

Background

Overactive bladder (OAB) affects 12 to 30% of the world’s population. The accompanying urinary urgency, frequency and incontinence can have a profound effect on quality of life, leading to depression, social isolation, avoidance of sexual activity and loss of productivity. Conservative measures such as lifestyle modification and pelvic floor physical therapy are the first line of treatment for overactive bladder. Patients who fail these may go on to take medications, undergo neuromodulation or receive injection of botulinum toxin into the bladder wall. While effective, medications have side effects and suffer from poor adherence. Neuromodulation and botulinum toxin injection are also effective but are invasive and not acceptable to some patients.

Methods

We have developed a novel transcutaneous spinal cord neuromodulator (SCONE™^,) that delivers multifrequency electrical stimulation to the spinal cord without the need for insertion or implantation of stimulating electrodes. Previously, multifrequency transcutaneous stimulation has been demonstrated to penetrate to the spinal cord and lead to motor activation of detrusor and external urethral sphincter muscles. Here, we report on eight patients with idiopathic overactive bladder, who underwent 12 weeks of SCONE™ therapy.

Results

All patients reported statistically significant clinical improvement in multiple symptoms of overactive bladder, such as urinary urgency, frequency and urge incontinence. In addition, patients reported significant symptomatic improvements as captured by validated clinical surveys.

Conclusion

SCONE™ therapy represents the first of its kind therapy to treat symptoms of urgency, frequency and urge urinary incontinence in patients with OAB.

Trial registration

The study was listed on clinicaltrials.gov (NCT03753750).

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.

Pelvic floor rehabilitation in the treatment of mixed urinary incontinence among women

Background

Mixed urinary incontinence (MUI) is a common underreported problem among females; it has a major effect on patients’ quality of life. Treatment may be difficult since a single modality cannot be enough to alleviate both the urge and the stress symptoms. Biofeedback-assisted pelvic floor muscle training (PFMT) has a great role in strengthening the pelvic floor muscles especially when accompanied by electrical stimulation. Neuromodulation is another safe well-tolerated method that may improve symptoms of female voiding dysfunction. There are no previous studies that assessed the efficacy of biofeedback-assisted pelvic floor muscle training versus two different types of peripheral neuromodulation which are transcutaneous posterior tibial nerve stimulation (TPTNS) and anogenital neuromodulation in the treatment of mixed urinary incontinence among women. The aim of this work is to study the effectiveness of biofeedback-assisted pelvic floor muscle training with electrostimulation versus two different methods of peripheral neuromodulation techniques in the treatment of women with MUI. Patients were subjected to history taking, assessment questionnaires (Questionnaire for female Urinary Incontinence Diagnosis (QUID), Australian Pelvic Floor Questionnaire (PFQ), and International Consultation on Incontinence Questionnaire-Urinary Incontinence-Short Form (ICIQ-UI-SF)), clinical examination, and manometric pressure assessment. The patients were allocated randomly into three groups. Group I received biofeedback-assisted pelvic floor muscle training and faradic electrical stimulation, group II received posterior tibial neuromodulation, and group III received anogenital neuromodulation.

Results

The present study included 68 non-virgin female patients with mixed urinary incontinence. Significant improvement was noticed in the three studied groups on the subjective and objective levels. No statistically significant difference was reported between the studied groups following the different types of intervention.

Conclusions

Biofeedback-assisted pelvic floor muscle training with electrostimulation is as effective as anogenital neuromodulation and posterior tibial neuromodulation in the treatment of mixed urinary incontinence among females.

Trial registration

PACTR, PACTR202107816829078. Registered 29 July 2021 - Retrospectively registered.

Cost-Effectiveness Analysis Between Sacral Neuromodulation and OnabotulinumtoxinA for the Treatment of Refractory Overactive Bladder in Women: A Systematic Review

OBJECTIVE

We summarized the evidence evaluating the cost-effectiveness of sacral neuromodulation (SNM) versus onabotulinumtoxinA (BONT/A) in the treatment of refractory overactive bladder (OAB) among women.

METHODS

We searched PubMed Medline (1946-2019), EMBASE (1947-2019), Web of Science (1900-2019), Clinical Trials.gov, reviewed references of included studies, and Cochrane subsets of CDSR, DARE, CENTRAL, and NHSEED. We included cost-utility and cost-effectiveness analyses or decision analysis comparing SNM versus BONT/A in women with nonneurogenic refractory OAB. Primary outcomes included incremental cost-effectiveness ratios (ICERs), reported as cost per quality-adjusted life year (QALY), which were abstracted or calculated.

RESULTS

Five studies met the inclusion criteria. Three studies were industry supported. Two studies of high quality found BONT/A to be dominant over SNM (ICER range of $415,571/QALY at 5 years and $236,370/QALY at 10 years). This trend was further supported by a third study of high quality that favored BONT/A because SNM was not cost-effective (ICER, $116,427/QALY at 2 years). In contrast, 2 other studies of lower quality found that SNM was cost-effective or dominant in comparison to BONT/A (ICER range, $3,717/QALY to €15,226/QALY at 10 years). In general, models were sensitive to treatment duration, intervention setting, and lacked robust data on long-term outcomes.

CONCLUSIONS

OnabotulinumtoxinA is more cost-effective for managing refractory OAB when compared with SNM. However, it remains unclear whether this finding holds true long term for what is considered a lifelong condition.

Kegel Exercises, Biofeedback, Electrostimulation, and Peripheral Neuromodulation Improve Clinical Symptoms of Fecal Incontinence and Affect Specific Physiological Targets: An Randomized Controlled Trial

Background/Aims

Fecal incontinence (FI) is a prevalent condition among community-dwelling women, and has a major impact on quality of life (QoL). Research on treatments commonly used in clinical practice—Kegel exercises, biofeedback, electrostimulation, and transcutaneous neuromodulation—give discordant results and some lack methodological rigor, making scientific evidence weak. The aim is to assess the clinical efficacy of these 4 treatments on community-dwelling women with FI and their impact on severity, QoL and anorectal physiology.

Methods

A randomized controlled trial was conducted on 150 females with FI assessed with anorectal manometry and endoanal ultrasonography, and pudendal nerve terminal motor latency, anal/rectal sensory-evoked-potentials, clinical severity, and QoL were determined. Patients were randomly assigned to one of the following groups Kegel (control), biofeedback + Kegel, electrostimulation + Kegel, and neuromodulation + Kegel, treated for 3 months and re-evaluated, then followed up after 6 months.

Results

Mean age was 61.09 ± 12.17. Severity of FI and QoL was significantly improved in a similar way after all treatments. The effect on physiology was treatment-specific Kegel and electrostimulation + Kegel, increased resting pressure (P < 0.05). Squeeze pressures strongly augmented with biofeedback + Kegel, electrostimulation + Kegel and neuromodulation + Kegel (P < 0.01). Endurance of squeeze increased in biofeedback + Kegel and electrostimulation + Kegel (P < 0.01). Rectal perception threshold was reduced in the biofeedback + Kegel, electrostimulation + Kegel, and neuromodulation + Kegel (P < 0.05); anal sensory-evoked-potentials latency shortened in patients with electrostimulation + Kegel (P < 0.05).

Conclusions

The treatments for FI assessed have a strong and similar efficacy on severity and QoL but affect specific pathophysiological mechanisms. This therapeutic specificity can help to develop more efficient multimodal algorithm treatments for FI based on pathophysiological phenotypes.

Predictive factors of PNE success in a contemporary series: A single institution experience

PURPOSE

Peripheral nerve evaluation (PNE) permits a trial of sacral neuromodulation to determine candidates for single stage implant. Before routine fluoroscopy, PNE success rates were 40%-50% compared to approximately 77% with staged procedures. There are limited data on PNE success rates with the use of fluoroscopy and improved techniques. We evaluated a contemporary series of PNE patients to determine predictors of PNE success and persistent functional response following permanent implantation.

METHODS

A retrospective review of PNE patients at a large academic center from 2015 to 2019 was performed. Patients with urgency-frequency, urge incontinence, and/or fecal incontinence (FI) were included. Rates of permanent implant after successful PNE trial and continued improvement at ≥1 month were reviewed. Multivariable logistic regression determined predictors of PNE success and continued response at follow-up.

RESULTS

A total of 102 PNE patients were included. A total of 78 patients (76.5%) were PNE responders. Predictors of PNE success included younger age (p = .014), urgency incontinence (p = .021), FI (p = .017), absence of a neurologic diagnosis (p = .04), presence of bellows and toe responses (p = .038), and perineal sensation (p = .027). A total of 68 of 78 PNE responders (87.2%) maintained optimal responses at ≥1 month. Absence of a neurologic diagnosis was predictive of persistent success at follow-up (p = .013).

CONCLUSIONS

This contemporary PNE series revealed screening success equivalent to a two-staged approach. A small proportion of patients demonstrate suboptimal responses following permanent implant. Conversion from testing to permanent implant may not be the ideal outcome as it may overestimate success, and evaluation for persistent improvement should be investigated further as a more reliable indicator of successful screening.

Functional segregation within the pelvic nerve of male rats: a meso- and microscopic analysis

The pelvic splanchnic nerves are essential for pelvic organ function and have been proposed as targets for neuromodulation. We have focused on the rodent homologue of these nerves, the pelvic nerves. Our goal was to define within the pelvic nerve the projections of organ-specific sensory axons labelled by microinjection of neural tracer (cholera toxin, subunit B) into the bladder, urethra or rectum. We also examined the location of peptidergic sensory axons within the pelvic nerves to determine whether they aggregated separately from sacral preganglionic and paravertebral sympathetic postganglionic axons travelling in the same nerve. To address these aims, microscopy was performed on the major pelvic ganglion (MPG) with attached pelvic nerves, microdissected from young adult male Sprague-Dawley rats (6-8 weeks old) and processed as whole mounts for fluorescence immunohistochemistry. The pelvic nerves were typically composed of five discrete fascicles. Each fascicle contained peptidergic sensory, cholinergic preganglionic and noradrenergic postganglionic axons. Sensory axons innervating the lower urinary tract (LUT) consistently projected in specific fascicles within the pelvic nerves, whereas sensory axons innervating the rectum projected in a complementary group of fascicles. These discrete aggregations of organ-specific sensory projections could be followed along the full length of the pelvic nerves. From the junction of the pelvic nerve with the MPG, sensory axons immunoreactive for calcitonin gene-related peptide (CGRP) showed several distinct patterns of projection: some projected directly to the cavernous nerve, others projected directly across the surface of the MPG to the accessory nerves and a third class entered the MPG, encircling specific cholinergic neurons projecting to the LUT. A subpopulation of preganglionic inputs to noradrenergic MPG neurons also showed CGRP immunoreactivity. Together, these studies reveal new molecular and structural features of the pelvic nerves and suggest functional targets of sensory nerves in the MPG. These anatomical data will facilitate the design of experimental bioengineering strategies to specifically modulate each axon class.

Outcomes of Intradetrusor Onabotulinum Toxin A Therapy in Overactive Bladder Refractory to Sacral Neuromodulation

Purpose

Intradetrusor onabotulinum toxin A (BTXA) and sacral neuromodulation (SNM) are effective third-line therapies for overactive bladder (OAB). We aimed to measure the outcomes of BTXA for treatment of OAB refractory to initial SNM and identify patient characteristics associated with these outcomes.

Methods

This retrospective cohort study included patients who failed to respond to initial SNM treatment for OAB and subsequently received BTXA at a single provider’s clinic between January 2013 and December 2016. Treatment successes were defined as patients willing to continue BTXA or who found symptom relief whereas treatment failures discontinued BTXA due to adverse effects or lack of symptom relief. Symptoms and patient-reported outcomes on validated questionnaires were compared before the initial BTXA trial to 2 months after the last BTXA treatment. The SNM failure BTXA groups were also compared to BTXA SNM naïve groups.

Results

Of 18 patients who received BTXA after failed SNM treatment, 7 (39%) achieved treatment success. Successfully treated patients demonstrated decreased urinary frequency from a median 11 voids/day pre-BTXA to 8 voids/day with BTXA (P=0.042). Patients whose treatment failed reported increased complaints of a weak urinary stream (P=0.03) and higher frequency of straining to urinate (P=0.016) than the successful treatment group pre-BTXA. Compared to BTXA patients without prior SNM, the odds of failing BTXA after initial SNM were 3.6 times higher (P=0.016).

Conclusions

BTXA appears effective for OAB refractory to SNM, although the success rate is lower compared to BTXA patients without SNM exposure.

Refractory Sexual Arousal Subsequent to Sacral Neuromodulation

Background

Sacral neuromodulation has become a widely used treatment for lower urinary tract symptom and dysfunction. It has been observed to benefit sexual function in the domains of arousal and desire. Studies have yet to report markedly increased arousal symptoms as an adverse effect.

Case

We present the case of a 57-year-old woman who developed symptomatic persistent genital arousal following implantation of a neuromodulator. Despite device reprogramming, a trial of the device being shut off, and eventual device removal, she continued to have residual new-onset undesired genital hyper-arousal symptoms.

Conclusion

Our patient demonstrated markedly increased and persistent arousal symptoms that may be the result of upregulated or alternative activation of sacral nerve pathways. While other case reports describe improvement in persistent genital arousal disorder symptoms through neuromodulation, no studies mention hyperarousal symptoms as an adverse side effect after sacral neuromodulator placement nor persistence despite removal of the implant.

Audiovisual stimulus during urodynamics to provoke detrusor overactivity: A randomized trial

OBJECTIVE

This study estimated the effect of adding an audiovisual (AV) intervention during urodynamic evaluation (UDE) on increasing detrusor contractions (DO) versus routine UDE testing without AV cues.

METHODS

A randomized trial was conducted of women with overactive bladder (OAB) undergoing UDE with and without AV intervention. The AV intervention was a 1-minute video on continuous loop showing common OAB triggers. A continuous running waterfall provided auditory stimulation. The primary outcome was the proportion of patients who had DO on UDE, interpreted by masked clinicians. Secondary outcomes included the number, amplitude, and duration of DO and urinary leakage associated with DO. A sample size of 109 per group was calculated to have 80% power to detect a 20% difference with a significance level of 0.05.

RESULTS

In all, 109 women each were randomized to standard UDE and to the AV intervention. There was no difference in the proportion of patients with DO on UDE between the intervention and control groups (35% vs 32%, respectively; P = 0.8). Furthermore, there were no differences between the intervention and control groups in leakage with DO on UDE (24% vs 21%, respectively), mean duration of detrusor contractions (23.9 vs 25.3 s, respectively), or mean maximum detrusor pressure during involuntary contractions (18.1 vs 20.6 cm H₂ O, respectively). Clinical severity of OAB symptoms was not associated with the detection of DO or other UDE parameters.

CONCLUSIONS

Addition of AV intervention during UDE did not increase the finding of detrusor contractions. The relationship between OAB triggers, urge incontinence, and urodynamic findings remains unclear.

Effect of Early Sacral Neuromodulation on Bladder Function in a Rat Model of Incomplete Spinal Cord Injury Due to Focal Contusion

OBJECTIVES

Incomplete spinal cord injury (SCI) accounts for two-thirds of all SCIs in clinical practice. Preclinical research on the effect of sacral neuromodulation (SNM) on bladder function, however, has been focused only on animal models of complete SCI. We aimed to evaluate the effect of early SNM on bladder responses in a rat model of incomplete SCI.

MATERIALS AND METHODS

Altogether, 21 female Sprague-Dawley rats were equally assigned to control (CTR), SCI + sham stimulation (SHAM), and SCI + SNM (SNM) groups. In the SHAM and SNM groups, incomplete SCI was created by producing a moderate contusion with an NYU-MASCIS impactor at the T9-T10 level of the spine, with needle electrodes implanted bilaterally into the S2 or S3 sacral foramen. Only SNM group underwent electrical stimulation for 28 days, beginning on day 7 after SCI. Cystometry was performed 35 days after SCI.

RESULTS

Although the interval between voiding contractions was significantly longer in the SHAM group than the CTR group (25.5 ± 1.4 vs. 12.5 ± 1.7 min; p < 0.05), there were no significant differences between the SNM group (16.5 ± 1.5 min) and the CTR group. Maximum voiding contraction pressure did not differ among the groups. The SNM group had a significantly lower frequency (3.5 ± 0.5 vs. 14.6 ± 2.0; p < 0.05) and maximum pressure (11.4 ± 6.2 vs. 21.3 ± 1.8 cmH₂ O; p < 0.05) of nonvoiding contractions than the SHAM group.

CONCLUSIONS

Our results provide experimental evidence that early SNM treatment may prevent or diminish bladder dysfunctions (e.g., detrusor overactivity, abnormal micturition reflex) in a clinical condition of incomplete SCI.

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.

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.

Urogenital Symptoms in Neurologic Patients

PURPOSE OF REVIEW

Lower urinary tract and sexual dysfunction are commonly reported sequelae of neurologic disease and have a significant impact on quality of life. This article presents an up-to-date summary of the clinical presentation, investigations, and treatment options for urogenital dysfunction in patients with neurologic disease.

RECENT FINDINGS

The pattern of lower urinary tract dysfunction is influenced by the site of the neurologic lesion. The risk for developing upper urinary tract damage is considerably less in patients with slowly progressive nontraumatic neurologic disorders, as compared to those with spinal cord injury or spina bifida. Investigations such as urinalysis, ultrasonography, and urodynamics provide further information about the cause and nature of lower urinary tract dysfunction. Antimuscarinic agents are the first-line management of urinary incontinence; however, side effect profile and anticholinergic burden should be considered when prescribing medications. β3-Adrenergic receptor agonists are a promising alternative oral medication. Tibial and sacral neuromodulation have been shown to be effective for managing incontinence, as well as urinary retention due to Fowler syndrome. Intradetrusor injections of onabotulinumtoxinA have revolutionized the management of neurogenic detrusor overactivity.

SUMMARY

Neurologic patients reporting urogenital symptoms require a comprehensive evaluation for planning a patient-tailored approach to management. Neurologists are increasingly inquiring about lower urinary tract and sexual functions and becoming involved in the management of these disorders.

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.

Parasacral transcutaneous electrical stimulation for overactive bladder in children: An assessment per session

OBJECTIVE

Neuromodulation has emerged as an effective therapeutic option for treatment of OAB in children. However, to our knowledge, no study has yet evaluated the results of neuromodulation on a session-by-session basis. The aim of this study was to evaluate the rate of complete response of overactive bladder (OAB) symptoms for each session of transcutaneous electrical stimulation (TENS), in a protocol of 20 sessions of therapy.

METHOD

This is a prospective study of the improvement of LUTS in children with isolated OAB. Included in this study were children over the age of 4 years who complained of urinary urgency, had bell-or tower-shaped uroflowmetry patterns, and post-void residual <10% of expected capacity for their age and/or less than 20 mL. No patient was treated with an anticholinergic. Children were excluded with lower urinary tract symptoms (LUTS) secondary to urinary tract abnormalities. All patients underwent parasacral transcutaneous neurostimulation (TENS). The development of symptoms was observed right before each session using a visual analog scale (VAS) in which 0 means the absence of improvement and 10 represents maximum improvement of symptoms.

RESULTS

We noted a complete resolution of symptoms (urgency, urge incontinence, frequency, and holding maneuvers) in some patients starting after the third session. In the 10th and 20th (last) sessions, 12 (17.4%) and 38 (55.1%) patients reported a complete resolution of symptoms. After complete resolution, 12 (17.4%) patients reported that their symptoms worsened to a minimum level of 40% improvement, but this was temporary and all returned to 100% improvement. Children who showed an improvement level greater than 50% in the fifth treatment session were 4.18 (p = 0.007) times more likely to have success in the last treatment session.

CONCLUSION

We found that a patient can experience complete symptom resolution as quickly as following the third session of TENS. The complete response rate progressively increases with the number of sessions, slowly until the 12th session and more rapidly after that. When symptom improvement of at least 50% is reported in the fifth session, there is a higher chance that the patient will have full resolution of symptoms at the end of treatment.

An Intermediate Animal Model of Spinal Cord Stimulation

Spinal cord injuries (SCI) result in the loss of movement and sensory feedback as well as organs dysfunctions. For example, nearly all SCI subjects loose their bladder control and are prone to kidney failure if they do not proceed to intermittent (self-) catheterization. Electrical stimulation of the sacral spinal roots with an implantable neuroprosthesis is a promising approach, with commercialized products, to restore continence and control micturition. However, many persons do not ask for this intervention since a surgical deafferentation is needed and the loss of sensory functions and reflexes become serious side effects of this procedure. Recent results renewed interest in spinal cord stimulation. Stimulation of existing pre-cabled neural networks involved in physiological processes regulation is suspected to enable synergic recruitment of spinal fibers. The development of direct spinal stimulation strategies aiming at bladder and bowel functions restoration would therefore appear as a credible alternative to existent solutions. However, a lack of suitable large animal model complicates these kinds of studies. In this article, we propose a new animal model of spinal stimulation -pig- and will briefly introduce results from one first acute experimental validation session.

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.

Lower urinary tract dysfunction in the neurological patient: clinical assessment and management

Lower urinary tract (LUT) dysfunction is a common sequela of neurological disease, resulting in symptoms that have a pronounced effect on quality of life. The site and nature of the neurological lesion affect the pattern of dysfunction. The risk of developing upper urinary tract damage and renal failure is much lower in patients with slowly progressive non-traumatic neurological disorders than in those with spinal cord injury or spina bifida; this difference in morbidity is taken into account in the development of appropriate management algorithms. Clinical assessment might include tests such as uroflowmetry, post-void residual volume measurement, renal ultrasound, (video-)urodynamics, neurophysiology, and urethrocystoscopy, depending on the indication. Incomplete bladder emptying is most often managed by intermittent catheterisation, and storage dysfunction by antimuscarinic drugs. Intradetrusor injections of onabotulinumtoxinA have transformed the management of neurogenic detrusor overactivity. Neuromodulation offers promise for managing both storage and voiding dysfunction. An individualised, patient-tailored approach is required for the management of LUT dysfunction associated with neurological disorders.

The technique of sacral nerve modulation

AIM

The aim of this review was to summarize current knowledge and recommendations regarding the technique of implantation of the electrode in performing sacroneuromodulation (SNM) and the available information on programming parameters and implantation algorithms.

METHOD

All English-language articles published from January 1985 to December 2013 that reported the SNM surgical technique and results were considered for inclusion. Data were considered useful for the present review only if related to: (i) peripheral nerve evaluation; (ii) temporary nerve stimulation; (iii) definitive impulse generator placement; and (iv) parameters programming.

RESULTS

The literature search revealed 193 potentially relevant studies from initial electronic search terms and eligibility criteria, and these studies were evaluated in detail. In total, 41 studies were included in the final analysis. Of the studies reviewed, the majority (n = 37) were prospective or retrospective case series. Only three randomized clinical trials were eligible for inclusion.

CONCLUSION

Although the technique seems to be standardized, several steps still need to be clarified in order to define the best way to perform the procedure and then to maximize the outcome.

[Physiotherapy and neurogenic lower urinary tract dysfunction in multiple sclerosis patients: a randomized controlled trial]

AIM

This randomized controlled trial compare the efficacy of pelvic floor muscle training vs. transcutaneous posterior tibial nerve stimulation.

PATIENTS AND METHODS

Inclusion criteria were EDSS score<7 and presence of lower urinary tract symptoms. Exclusion criteria were multiple sclerosis relapse during the study, active urinary tract infection and pregnancy. The primary outcome was quality of life (SF-Qualiveen questionnaire). Secondary outcomes included overactive bladder (USP questionnaire) score and frequency of urgency episodes (3-day bladder diary). Sample size was calculated after 18 patients were included. Data analysis was blinded. Each patient received 9 sessions of 30 minutes weekly. Patients were randomized in pelvic floor muscles exercises with biofeedback group (muscle endurance and relaxation) or transcutaneous posterior tibial nerve stimulation group (rectangular alternative biphasic current with low frequency).

RESULTS

A total of 31 patients were included. No difference appeared between groups for quality of life, overactive bladder and frequency of urgency episodes (respectively P=0.197, P=0.532 et P=0.788). These parameters were significantly improved in pelvic floor muscle training group (n=16) (respectively P=0.004, P=0.002 et P=0.006) and in transcutaneous posterior tibial nerve stimulation group (n=15) (respectively P=0.001, P=0.001 et P=0.031).

CONCLUSIONS

Pelvic floor muscle training and transcutaneous posterior tibial nerve stimulation improved in the same way symptoms related to urgency in MS patients with mild disability.

LEVEL OF EVIDENCE

2.

The Three Axial Perineal Evaluation (TAPE) score: a new scoring system for comprehensive evaluation of pelvic floor function

AIM

Abnormalities of one pelvic floor compartment are usually associated with anomalies in the other compartments. Therapies which specifically address one clinical problem may potentially adversely affect other pelvic floor activities. A new comprehensive holistic scoring system defining global pelvic function is presented.

METHOD

A novel scoring system with a software program is presented expressing faecal, urinary and gynaecological functions as a geometric polygon based on symptom-specific questionnaires [the three axial pelvic evaluation (TAPE) score] where differences in overall geometric area vary from normal. After validation in healthy volunteers, its clinical performance was tested on patients with obstructed defaecation, genital prolapse and urinary/faecal incontinence treated by the stapled transanal rectal resection (STARR) procedure, colpo-hysterectomy and sacral nerve modulation, respectively. The TAPE score was correlated with the Pelvic Floor Impact Questionnaire 7 quality of life score.

RESULTS

There was good inter-observer variation and internal consistency between two observers recording the TAPE score in normal volunteers. In the STARR patients, constipation improved but the TAPE score was unchanged because of deterioration in other pelvic floor functions leading to an unchanged overall postoperative recorded quality of life. Conversely, incontinent patients treated with sacral nerve stimulation improved their function showing concomitant improvements in TAPE scores and quality of life indices. Similar correlative improvements were noted in patients undergoing hysterectomy for genital prolapse.

CONCLUSION

The TAPE score defines the impact of symptom-specific treatments on the pelvic floor and may provide an opportunity for comparison of clinical data between units and in clinical trials of specific medical and surgical pelvic floor management.

Long-term follow-up of sacral neuromodulation for lower urinary tract dysfunction

OBJECTIVE

To report our long-term experience of sacral neuromodulation (SNM) for various lower urinary tract dysfunctions but with a focus on efficacy, safety, re-interventions and degree of success.

PATIENTS AND METHODS

This is a single tertiary referral centre study that included 217 patients (86% female) who received an implantable pulse generator (IPG) (Interstim™, Medtronic, Minneapolis, USA) between 1996 and 2010. Success was considered if the initial ≥50% improvement in any of primary voiding diary variables persisted compared with baseline, but was further stratified.

RESULTS

The mean duration of follow-up was 46.88 months. Success and cure rates were ≈70% and 20% for urgency incontinence, 68% and 33% for urgency frequency syndrome and 73% and 58% for idiopathic retention. In those patients with an unsuccessful therapy outcome, the mean time to failure was 24.6 months after implantation. There were 88 (41%) patients who had at least one device or treatment related surgical re-intervention. The re-intervention rate was 1.7 per patient with most of them (47%) occurring ≤2 years of follow-up.

CONCLUSIONS

SNM appears effective in the long-term with a success rate after definitive IPG implant of ≈70% and complete cure rates ranging between 20% and 58% depending on indication. Patients with idiopathic retention appear to do best. The re-intervention rate is high with most occurring ≤2 years of implantation. It is likely that with the newer techniques used, efficacy and re-intervention rates will improve.

Electrical and mechanical office-based neuromodulation

Overactive bladder (OAB) is commonly encountered in urologic practice. Treatment algorithms begin with conservative therapy and pharmacotherapy with antimuscarinics. Some patients do not receive adequate relief from these methods or they do not tolerate side effects from pharmacotherapy. A test stimulation for sacral neuromodulation and percutaneous tibial nerve stimulation are office-based techniques that are commonly used as the next step in the algorithm of care in patients with OAB. These techniques are efficacious and approved by the Food and Drug Administration for treatment of overactive bladder and its associated symptoms.

Neural pathways involved in sacral neuromodulation of reflex bladder activity in cats

This study examined the mechanisms underlying the effects of sacral neuromodulation on reflex bladder activity in chloralose-anesthetized cats. Bladder activity was recorded during cystometrograms (CMGs) or under isovolumetric conditions. An S1-S3 dorsal (DRT) or ventral root (VRT) was electrically stimulated at a range of frequencies (1-30 Hz) and at intensities relative to threshold (0.25-2T) for evoking anal/toe twitches. Stimulation of DRTs but not VRTs at 1T intensity and frequencies of 1-30 Hz inhibited isovolumetric rhythmic bladder contractions. A 5-Hz DRT stimulation during CMGs was optimal for increasing (P < 0.05) bladder capacity (BC), but stimulation at 15 and 30 Hz was ineffective. Stimulation of the S1 DRT was more effective (increases BC to 144% and 164% of control at 1T and 2T, respectively) than S2 DRT stimulation (increases BC to 132% and 150% of control). Bilateral transection of the hypogastric or pudendal nerves did not change the inhibitory effect induced by S1 DRT stimulation. Repeated stimulation of S1 and S2 DRTs during multiple CMGs elicited a significant (P < 0.05) increase in BC (to 155 ± 11% of control) that persisted after termination of the stimulation. These results in cats suggest that the inhibition of reflex bladder activity by sacral neuromodulation occurs primarily in the central nervous system by inhibiting the ascending or descending pathways of the spinobulbospinal micturition reflex.

Turning off sacral nerve stimulation does not affect gastric and small intestinal motility in patients treated for faecal incontinence

AIM

Sacral nerve stimulation (SNS) reduces symptoms in up to 80% of patients with faecal incontinence (FI). Its effects are not limited to the distal colon and the pelvic floor. Accordingly, spinal or supraspinal neuromodulation have been suggested as part of the mode of action. The effect of SNS on gastric and small-intestinal motility was studied.

METHOD

Using the magnet tracking system, MTS-1, a small magnetic pill was tracked twice through the upper gastrointestinal tract of eight patients with FI successfully treated with SNS. Following a randomized double-blind crossover design, the stimulator was either left active or was turned off for 1 week before investigations with MTS-1.

RESULTS

The median (range) frequency of gastric con-tractions was 3.05 (2.83-3.40) per min during SNS and 3.04 (2.79?-3.76) per min without (P=NS). The median (range) frequency of contractions in the small intestine during the first 2h after pyloric passage was 10.005 (9.68-10.70) per min during SNS and 10.09 (9.79-10.29) per min without SNS (P=NS). The median (range) velocity of the magnetic pill during the first 2h in the small intestine was 1.6 (1.2-2.8) cm/min during SNS and 1.7 (0.8-3.7) cm/min without SNS (P=NS). Small-intestinal propagation mainly occurred during very fast movements (>15cm/min), accounting for 51% (42-60%) of the distance 3% (2-4%) of the time during SNS and for 53% (18-73%) of the distance 3% (1-8%) of the time without SNS (P=NS).

CONCLUSION

Turning off SNS for 1week did not affect gastric or small-intestinal motility patterns.