Electro‐Neuromodulation for Colonic Disorders—Review of Meta‐Analyses, Systematic Reviews, and RCTs

Neuromodulation and Functional Gastrointestinal Disease

INTRODUCTION

Functional gastrointestinal disorders (FGIDs) are common, and they severely impair an individual's quality of life. The mechanism of pathogenesis and the effective treatments for FGIDs remain elusive. Neuromodulation-a relatively new treatment-has exhibited a good therapeutic effect on FGIDs, although there are different methods for different symptoms of FGIDs.

MATERIALS AND METHODS

We used PubMed to review the history of neuromodulation for the treatment of FGIDs and to review several recently proposed neuromodulation approaches with improved effects on FGIDs.

CONCLUSION

Electroacupuncture, transcutaneous electroacupuncture, transcutaneous auricular vagal nerve stimulation, sacral nerve stimulation (SNS) (which relies on vagal nerve stimulation), and gastric electrical stimulation (which works through the modulation of slow waves generated by the interstitial cells of Cajal), in addition to the noninvasive neurostimulation alternative approach method of SNS-tibial nerve stimulation and transcutaneous electrical stimulation (which is still in its infancy), are some of the proposed neuromodulation approaches with improved effects on FGIDs. This review has discussed some critical issues related to the selection of stimulation parameters and the underlying mechanism and attempts to outline future research directions backed by the existing literature.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Strategies used for childhood chronic functional constipation: the SUCCESS evidence synthesis

Background

Up to 30% of children have constipation at some stage in their life. Although often short-lived, in one-third of children it progresses to chronic functional constipation, potentially with overflow incontinence. Optimal management strategies remain unclear.

Objective

To determine the most effective interventions, and combinations and sequences of interventions, for childhood chronic functional constipation, and understand how they can best be implemented.

Methods

Key stakeholders, comprising two parents of children with chronic functional constipation, two adults who experienced childhood chronic functional constipation and four health professional/continence experts, contributed throughout the research. We conducted pragmatic mixed-method reviews. For all reviews, included studies focused on any interventions/strategies, delivered in any setting, to improve any outcomes in children (0-18 years) with a clinical diagnosis of chronic functional constipation (excluding studies of diagnosis/assessment) included. Dual reviewers applied inclusion criteria and assessed risk of bias. One reviewer extracted data, checked by a second reviewer. Scoping review: We systematically searched electronic databases (including Medical Literature Analysis and Retrieval System Online, Excerpta Medica Database, Cumulative Index to Nursing and Allied Health Literature) (January 2011 to March 2020) and grey literature, including studies (any design) reporting any intervention/strategy. Data were coded, tabulated and mapped. Research quality was not evaluated. Systematic reviews of the evidence of effectiveness: For each different intervention, we included existing systematic reviews judged to be low risk of bias (using the Risk of Bias Assessment Tool for Systematic Reviews), updating any meta-analyses with new randomised controlled trials. Where there was no existing low risk of bias systematic reviews, we included randomised controlled trials and other primary studies. The risk of bias was judged using design-specific tools. Evidence was synthesised narratively, and a process of considered judgement was used to judge certainty in the evidence as high, moderate, low, very low or insufficient evidence. Economic synthesis: Included studies (any design, English-language) detailed intervention-related costs. Studies were categorised as cost-consequence, cost-effectiveness, cost-utility or cost-benefit, and reporting quality evaluated using the consensus health economic criteria checklist. Systematic review of implementation factors: Included studies reported data relating to implementation barriers or facilitators. Using a best-fit framework synthesis approach, factors were synthesised around the consolidated framework for implementation research domains.

Results

Stakeholders prioritised outcomes, developed a model which informed evidence synthesis and identified evidence gaps.

Scoping review

651 studies, including 190 randomised controlled trials and 236 primary studies, conservatively reported 48 interventions/intervention combinations.

Effectiveness systematic reviews

studies explored service delivery models (n = 15); interventions delivered by families/carers (n = 32), wider children's workforce (n = 21), continence teams (n = 31) and specialist consultant-led teams (n = 42); complementary therapies (n = 15); and psychosocial interventions (n = 4). One intervention (probiotics) had moderate-quality evidence; all others had low to very-low-quality evidence. Thirty-one studies reported evidence relating to cost or resource use; data were insufficient to support generalisable conclusions. One hundred and six studies described implementation barriers and facilitators.

Conclusions

Management of childhood chronic functional constipation is complex. The available evidence remains limited, with small, poorly conducted and reported studies. Many evidence gaps were identified. Treatment recommendations within current clinical guidelines remain largely unchanged, but there is a need for research to move away from considering effectiveness of single interventions. Clinical care and future studies must consider the individual characteristics of children.

Study registration

This study is registered as PROSPERO CRD42019159008.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 128470) and is published in full in Health Technology Assessment; Vol. 28, No. 5. See the NIHR Funding and Awards website for further award information.

Efficacy and safety of electroacupuncture for secondary constipation: a systematic review and meta-analysis

OBJECTIVE

Secondary constipation refers to constipation that occurs after certain diseases or medications, such as acute stroke or opioids, and the efficacy of electroacupuncture for secondary constipation is controversial. So, this study aimed to explore the efficacy and safety of electroacupuncture for secondary constipation through a meta-analysis and systematic review.

METHOD

We retrieved articles from PubMed, Embase, Cochrane Library, Web of Science, CNKI, Wanfang, and VIP databases up to 28 February 2023. The study was screened strictly according to inclusion and exclusion criteria. Revman5.4 was used for quality evaluation; grade rating was used for index evaluation, and stata15.0 was used for data consolidation analysis.

RESULT

Thirteen randomized controlled studies, involving a total of 1437 people (722 electroacupuncture and 715 control groups), were included in this review. Meta-analysis results indicated that electroacupuncture significantly improved constipation overall response (RR = 1.31, 95%CI: 1.11, 1.55, P < 0.001), reduced defecation straining score (MD =  - 0.46, 95%CI: - 0.67, - 0.251, P < 0.001), increased weekly complete spontaneous bowel movements (MD = 0.41, 95%CI: 0.20, 0.63, P = 0.002), and increased in the weekly spontaneous bowel movements (MD = 0.80, 95%CI (0.49, 01.11), P < 0.001), and electroacupuncture had no effect on change stool consistency score compared (MD =  - 0.03, 95%CI (- 0.38, 0.33), P = 0.88) and did not increase adverse events (RR = 0.50, 95%CI: 0.18, 1.44, P = 0.20).

CONCLUSION

According to the current studies, the overall relief rate of patients with secondary constipation after electroacupuncture treatment was improved, the defecation pressure score was reduced, the weekly natural defecation was more complete, and adverse reactions were not increased. Electroacupuncture therefore shows potential for treating constipation, but more high-quality studies are needed to confirm these findings.

Neurophysiological Effects of Electrical Stimulation on a Patient with Neurogenic Bowel Dysfunction and Cauda Equina Syndrome after Spinal Anesthesia: A Case Report

Neurogenic bowel dysfunction (NBD) is common in patients with cauda equina syndrome (CES). Previous studies have reported that electrical stimulation (ES) improves NBD but more neurophysiologic evidence is required. This case report describes a patient who experienced difficulty with defecation as a result of cauda equina syndrome (CES) that developed after a cesarean section performed 12 years ago under spinal anesthesia. The neurophysiological effects were assessed using the bulbocavernosus reflex (BCR) and electromyography (EMG). Two ES treatments, interferential current therapy and transcutaneous electrical stimulation, were used to stimulate the intestine and the external anal sphincter, respectively. The BCR results showed right-side delayed latency and no response on the left side. Needle EMG revealed abnormal spontaneous activities of the bilateral bulbocavernosus (BC) muscles. Electrodiagnostic testing revealed chronic bilateral sacral polyradiculopathy, compatible with CES. After treatment, the patient reported an improved perianal sensation, less strain and time for defecation than before, and satisfaction with her bowel condition. At the follow-up electrodiagnosis, the BCR latency was normal on the right side—needle EMG revealed reductions in the abnormal spontaneous activities of both BC muscles and re-innervation of the right BC muscle. Electrodiagnostic testing can offer insight into the neurophysiological effects of ES, which can help in understanding the mechanism of action and optimizing the therapy for patients with NBD.

Transcutaneous Electrical Acustimulation Improves Constipation by Enhancing Rectal Sensation in Patients With Functional Constipation and Lack of Rectal Sensation

INTRODUCTION

Reduced rectal sensation is involved in the pathophysiology of constipation. The aim of this study was to investigate the effects of transcutaneous electrical acustimulation (TEA) at acupuncture point ST36 on constipation and rectal sensation as well as autonomic functions in patients with constipation and reduced rectal sensation.

METHODS

In an acute study, anorectal motility and sensation tests were performed in constipation patients (N = 53) who were treated with TEA at ST36 or sham points. In a chronic study, patients (N = 18) underwent 2 weeks of TEA or sham-TEA in a crossover design.

RESULTS

Chronic TEA increased spontaneous bowel movements (3.72 vs 2.00 per week with sham-TEA, P < 0.0001) and significantly reduced constipation symptoms and increased quality of life in comparison with sham-TEA (P < 0.05). Acute TEA reduced the sensation threshold in response to rectal distention for the urge of defecation and maximum tolerable volume (P < 0.05, vs baseline); chronic TEA reduced the sensation thresholds for first sensation and desire of defecation, and decreased the threshold volume to an elicit rectal anal inhibitory reflex (P < 0.05). Both acute and chronic TEA increased parasympathetic activity (P < 0.05).

DISCUSSION

TEA at ST36 improves chronic constipation by enhancing rectal sensation possibly mediated by the reinforcement of parasympathetic activity in patients with functional constipation and reported lack/absence of rectal sensation.

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

INTRODUCTION

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

RESULTS

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

CONCLUSION

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

Efficacy of acupuncture based on acupoint combination theory for irritable bowel syndrome: a study protocol for a multicenter randomized controlled trial

Background

Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder characterized by abdominal pain, diarrhea or constipation, and changes in defecation patterns. No organic disease is found to explain these symptoms by routine clinical examination. This study aims to investigate the efficacy and safety of acupuncture therapy for IBS patients compared with those of conventional treatments. We also aim to identify the optimal acupoint combination recommended for IBS and to clarify the clinical advantage of the “multiacupoint co-effect and synergistic effect.”

Methods and analysis

A total of 204 eligible patients who meet the Rome IV criteria for IBS will be randomly stratified into acupuncture group A, acupuncture group B, or the control group in a 1:1:1 ratio with a central web-based randomization system. The prespecified acupoints used in the control group will include bilateral Tianshu (ST25), Shangjuxu (ST37), Neiguan (PC6), and Zusanli (ST36). The prespecified acupoints used in experimental group A will include bilateral Tianshu (ST25), Shangjuxu (ST37), and Neiguan (PC6). The prespecified acupoints used in experimental group B will include bilateral Tianshu (ST25), Shangjuxu (ST37), and Zusanli (ST36). Each patient will receive 12 acupuncture treatments over 4 weeks and will be followed up for 4 weeks. The primary outcome is the IBS-Symptom Severity Scale (IBS-SSS) score. The secondary outcomes include the Bristol Stool Form Scale (BSFS), Work and Social Adjustment Score (WSAS), IBS-Quality of Life (IBS-QOL), Self-Rating Anxiety Scale (SAS), and Self-Rating Depression Scale (SDS) scores. Both the primary outcome and the secondary outcome measures will be collected at baseline, at 2 and 4 weeks during the intervention, and at 6 weeks and 8 weeks after the intervention.

Ethics and dissemination

The entire project has been approved by the ethics committee of the Beijing University of Chinese Medicine (2020BZYLL0903).

Discussion

This is a multicenter randomized controlled trial for IBS in China. The findings may shed light on the efficacy of acupuncture as an alternative to conventional IBS treatment. The results of the trial will be disseminated in peer-reviewed publications.

Trial registration

Chinese Clinical Trials Register ChiCTR2000041215. First registered on 12 December 2020. http://www.chictr.org.cn/.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The effect of colonic tissue electrical stimulation and celiac branch of the abdominal vagus nerve neuromodulation on colonic motility in anesthetized pigs

BACKGROUND

Knowledge on optimal electrical stimulation (ES) modalities and region-specific functional effects of colonic neuromodulation is lacking. We aimed to map the regional colonic motility in response to ES of (a) the colonic tissue and (b) celiac branch of the abdominal vagus nerve (CBVN) in an anesthetized porcine model.

METHODS

In male Yucatan pigs, direct ES (10 Hz, 2 ms, 15 mA) of proximal (pC), transverse (tC), or distal (dC) colon was done using planar flexible multi-electrode array panels and CBVN ES (2 Hz, 0.3-4 ms, 5 mA) using pulse train (PT), continuous (10 min), or square-wave (SW) modalities, with or without afferent nerve block (200 Hz, 0.1 ms, 2 mA). The regional luminal manometric changes were quantified as area under the curve of contractions (AUC) and luminal pressure maps generated. Contractions frequency power spectral analysis was performed. Contraction propagation was assessed using video animation of motility changes.

KEY RESULTS

Direct colon ES caused visible local circular (pC, tC) or longitudinal (dC) muscle contractions and increased luminal pressure AUC in pC, tC, and dC (143.0 ± 40.7%, 135.8 ± 59.7%, and 142.0 ± 62%, respectively). The colon displayed prominent phasic pressure frequencies ranging from 1 to 12 cpm. Direct pC and tC ES increased the dominant contraction frequency band (1-6 cpm) power locally. Pulse train CBVN ES (2 Hz, 4 ms, 5 mA) triggered pancolonic contractions, reduced by concurrent afferent block. Colon contractions propagated both orally and aborally in short distances.

CONCLUSION AND INFERENCES

In anesthetized pigs, the dominant contraction frequency band is 1-6 cpm. Direct colonic ES causes primarily local contractions. The CBVN ES-induced pancolonic contractions involve central neural network.

Assessment of Needs in Children Suffering From Refractory Non-neurogenic Urinary and Fecal Incontinence and Their Caregivers' Needs and Attitudes Toward Alternative Therapies (SNM, TENS)

Background: Non-neurogenic urinary and fecal incontinence (UI, FI) affects approximately 6% of North American children with 1% of cases becoming refractory (nonresponsive to standard therapies). Incontinence has major potential long-term physiological and psychological implications for patients and their families. While Sacral Neuromodulation (SNM) and Transcutaneous Nerve Stimulation (TENS) are alternative therapies available for the treatment of refractory UI/FI, these are not approved for use in children in Canada. The present study assessed participants' perception of current treatments, incontinence burden, and attitudes toward novel therapies in a single pediatric institution. Methods: Multiple validated questionnaires including Dysfunctional Voiding Scoring System (DVSS), Bristol Stool Chart (BSC), Pediatric Incontinence measurement (PinQ), and Time-Driven Activity Based Costing were used to perform a needs assessment for patients with non-neurogenic refractory incontinence, and to determine patients' and caregivers' attitudes toward alternative therapies. Results: 75% of patients and 89% of caregivers reported a moderate to severe impact of incontinence on QoL with diminished social interactions among the primary concerns. Caregivers were frustrated with current treatments and were open to trying alternative therapies (SNM and TENS), which, at least in the case of SNM, seems to be less expensive, possibly less burdensome and more effective than current surgical options. Conclusion: Pediatric refractory UI/FI has a large impact on patients' and caregivers' QoL and alternative therapies with the potential to improve QoL of patients and caregivers should be further investigated as a substitute for surgery.