Cortico-anorectal, Spino-anorectal, and Cortico-spinal Nerve Conduction and Locus of Neuronal Injury in Patients With Fecal Incontinence

Electroceuticals and Magnetoceuticals in Gastroenterology

In the realm of gastroenterology, the inadequacy of current medical treatments for gastrointestinal (GI) motility disorders and inflammatory bowel disease (IBD), coupled with their potential side effects, necessitates novel therapeutic approaches. Neuromodulation, targeting the nervous system's control of GI functions, emerges as a promising alternative. This review explores the promising effects of vagal nerve stimulation (VNS), magnetic neuromodulation, and acupuncture in managing these challenging conditions. VNS offers targeted modulation of GI motility and inflammation, presenting a potential solution for patients not fully relieved from traditional medications. Magnetic neuromodulation, through non-invasive means, aims to enhance neurophysiological processes, showing promise in improving GI function and reducing inflammation. Acupuncture and electroacupuncture, grounded in traditional medicine yet validated by modern science, exert comprehensive effects on GI physiology via neuro-immune-endocrine mechanisms, offering relief from motility and inflammatory symptoms. This review highlights the need for further research to refine these interventions, emphasizing their prospective role in advancing patient-specific management strategies for GI motility disorders and IBD, thus paving the way for a new therapeutic paradigm.

Evaluation of bidirectional gut-brain axis and anorectal function in Parkinson's disease with constipation

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative movement disorder with prodromal and highly prevalent gastrointestinal (GI) symptoms, especially constipation. Although PD models suggest gut-brain axis dysfunction, the mechanistic underpinnings and their correlation with GI symptoms are poorly understood.

AIM

To examine the bidirectional gut-brain axis function in PD and correlate it with constipation severity, PD duration, and severity.

METHODS

Rectal sensory thresholds and afferent cortical evoked potentials (CEP) were assessed using a 4-ring EMG electrode probe. Efferent anal and rectal motor evoked potentials (MEPs) were obtained following transcranial and lumbosacral magnetic stimulation. Bowel symptoms were assessed by prospective stool diary. The CEP and MEP latencies, rectal sensory thresholds, and anorectal sensorimotor data were compared between PD subjects and age-adjusted healthy subjects.

KEY RESULTS

Twenty-five PD subjects with constipation (F/M = 6/19) and 20 healthy subjects (F/M = 14/6) were enrolled. The first and pain sensation thresholds were higher in PD subjects than healthy subjects (p < 0.002) but lost significance after adjustment for age. Age-adjusted rectal CEP and right-sided cortico-anal MEP latencies were prolonged in PD subjects compared to healthy subjects (p < 0.04). Also, half (4 of 8) age-adjusted spino-anal and rectal MEP latencies in PD subjects were significantly longer. In multivariate linear analysis, first rectal sensation and right-sided MEP latencies showed moderate correlation with constipation severity.

CONCLUSIONS & INFERENCES

Parkinson's disease is associated with significant bidirectional gut-brain axis dysfunction as evidenced by prolonged afferent and efferent neuronal signaling. Constipation severity in PD is correlated to abnormal rectal sensation and lateralized disturbance of efferent brain-gut signaling.

Clinical utility of trans-sacral magnetic stimulation-evoked sphincter potentials and high-density electromyography in pelvic floor assessment: Technical evaluation

AIM

Faecal incontinence is common and of multifactorial aetiologies, yet current diagnostic tools are unable to assess nerve and sphincter function objectively. We developed an anorectal high-density electromyography (HD-EMG) probe to evaluate motor-evoked potentials induced via trans-sacral magnetic stimulation (TSMS).

METHOD

Anorectal probes with an 8 × 8 array of electrodes spaced 1 cm apart were developed for recording HD-EMG of the external anal sphincter. These HD-EMG probes were used to map MEP amplitudes and latencies evoked via TSMS delivered through the Magstim Rapid2 (MagStim Company). Patients undergoing pelvic floor investigations were recruited for this IDEAL Stage 2a pilot study.

RESULTS

Eight participants (median age 49 years; five female) were recruited. Methodological viability, safety and diagnostic workflow were established. The test was well tolerated with median discomfort scores ≤2.5/10, median pain scores ≤1/10 and no adverse events. Higher Faecal Incontinence Severity Index scores correlated with longer MEP latencies (r = 0.58, p < 0.001) and lower MEP amplitudes (r = -0.32, p = 0.046), as did St. Mark's Incontinence Scores with both MEP latencies (r = 0.49, p = 0.001) and MEP amplitudes (r = -0.47, p = 0.002).

CONCLUSION

This HD-EMG probe in conjunction with TSMS presents a novel diagnostic tool for anorectal function assessment. Spatiotemporal assessment of magnetically stimulated MEPs correlated well with symptoms and offers a feasible, safe and patient-tolerable method of evaluating pudendal nerve and external anal sphincter function. Further clinical development and evaluation of these techniques is justified.

Faecal incontinence in adults

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

Translumbosacral Anorectal Magnetic Stimulation Test for Fecal Incontinence

BACKGROUND

Neuropathy may cause fecal incontinence and mixed fecal incontinence/constipation, but its prevalence is unclear, partly due to the lack of comprehensive testing of spino-anorectal innervation.

OBJECTIVE

This study aimed to develop and determine the clinical usefulness of a novel test, translumbosacral anorectal magnetic stimulation for fecal incontinence.

DESIGN

This observational cohort study was conducted from 2012 to 2018.

SETTINGS

This study was performed at a tertiary referral center.

PATIENTS

Patients with fecal incontinence, patients with mixed fecal incontinence/constipation, and healthy controls were included.

INTERVENTIONS

A translumbosacral anorectal magnetic stimulation test was performed by using an anorectal probe with 4 ring electrodes and magnetic coil, and by stimulating bilateral lumbar and sacral plexuses, uses and recording 8 motor-evoked potentials at anal and rectal sites.

MAIN OUTCOME MEASURES

The prevalence of lumbar and/or sacral neuropathy was examined. Secondary outcomes were correlation of neuropathy with anorectal sensorimotor function(s) and morphological changes.

RESULTS

We evaluated 220 patients: 144 with fecal incontinence, 76 with mixed fecal incontinence/constipation, and 31 healthy controls. All 8 lumbar and sacral motor-evoked potential latencies were significantly prolonged (p < 0.01) in fecal incontinence and mixed fecal incontinence/constipation groups compared with controls. Neuropathy was patchy and involved 4.0 (3.0) (median (interquartile range)) sites. Lumbar neuropathy was seen in 29% to 65% of the patients in the fecal incontinence group and 22% to 61% of the patients in the mixed fecal incontinence/constipation group, and sacral neuropathy was seen in 24% to 64% and 29% to 61% of these patients. Anal neuropathy was significantly more (p < 0.001) prevalent than rectal neuropathy in both groups. There was no correlation between motor-evoked potential latencies and anal sphincter pressures, rectal sensation, or anal sphincter defects.

LIMITATIONS

No comparative analysis with electromyography was performed.

CONCLUSION

Lumbar or sacral plexus neuropathy was detected in 40% to 75% of patients with fecal incontinence with a 2-fold greater prevalence at the anal region than the rectum. Lumbosacral neuropathy appears to be an independent mechanism in the pathogenesis of fecal incontinence, unassociated with other sensorimotor dysfunctions. Translumbosacral anorectal magnetic stimulation has a high yield and is a safe and clinically useful neurophysiological test. See Video Abstract at http://links.lww.com/DCR/B728.

PRUEBA DE ESTIMULACIN MAGNTICA TRANSLUMBOSACRAL ANORECTAL PARA LA INCONTINENCIA FECAL

ANTECEDENTES:La neuropatía puede causar incontinencia fecal y una combinación de incontinencia fe-cal/estreñimiento, pero su prevalencia no está clara, en parte debido a la falta de pruebas comple-tas de inervación espino-anorrectal.OBJETIVO:Desarrollar y determinar la utilidad clínica de una nueva prueba, estimulación magnética trans-lumbosacral anorrectal para la incontinencia fecal.DISEÑO:Estudio de cohorte observacional del 2012 al 2018.ENTORNO CLINICO:Centro de referencia terciario.PACIENTES:Pacientes con incontinencia fecal, combinación de incontinencia fecal/estreñimiento y controles sanos.INTERVENCIONES:Se realizó una prueba de estimulación magnética translumbosacral anorrectal utilizando una sonda anorrectal con 4 electrodos anulares y bobina magnética, y estimulando los plexos lumbares y sacros bilaterales y registrando ocho potenciales evocados motores las regiones anal y rectal.PRINCIPALES MEDIDAS DE RESULTADO:Se examinó la prevalencia de neuropatía lumbar y/o sacra. Los resultados secundarios fueron la correlación de la neuropatía con las funciones sensitivomotoras anorrectales y cambios morfológi-cos.RESULTADOS:Evaluamos 220 pacientes, 144 con incontinencia fecal, 76 con combinación de incontinencia fe-cal/estreñimiento y 31 sujetos sanos. Las ocho latencias de los potenciales evocadas motoras lum-bares y sacras se prolongaron significativamente (p <0,01) en la incontinencia fecal y el grupo mixto en comparación con los controles. La neuropatía fue irregular y afectaba 4,0 (3,0) (mediana (rango intercuartílico) sitios. Se observó neuropatía lumbar en 29-65% en la incontinencia fecal y 22-61% en el grupo mixto, y neuropatía sacra en 24-64% y 29-61 % de pacientes respectivamen-te. La neuropatía anal fue significativamente más prevalente (p <0,001) que la rectal en ambos grupos. No hubo correlación entre las latencias de los potenciales evocadas motoras y las presio-nes del esfínter anal, la sensación rectal o los defectos del esfínter anal.LIMITACIONES:Sin análisis comparativo con electromiografía.CONCLUSIÓNES:Se detectó neuropatía del plexo lumbar o sacro en el 40-75% de los pacientes con incontinencia fecal con una prevalencia dos veces mayor en la región anal que en el recto. La neuropatía lumbo-sacra parece ser un mecanismo independiente en la patogenia de la incontinencia fecal, no asocia-do con otras disfunciones sensitivomotoras. La estimulación magnética translumbosacral anorrec-tal tiene un alto rendimiento, es una prueba neurofisiológica segura y clínicamente útil. Consulte Video Resumen en http://links.lww.com/DCR/B728.

Effects of Translumbosacral Neuromodulation Therapy on Gut and Brain Interactions and Anorectal Neuropathy in Fecal Incontinence: A Randomized Study

OBJECTIVES

Translumbosacral neuromodulation therapy (TNT) improves symptoms of fecal incontinence (FI), but its mechanism of action is unknown. We tested the hypothesis that TNT at one or more frequency will significantly improve underlying pathophysiology of FI through modulation of ascending and/or descending signaling pathways in the gut and brain axis and anorectal sensorimotor function.

MATERIALS AND METHODS

We assessed afferent anorectal-cortical evoked potentials (CEP) following electrical stimulation of anorectum, efferent cortico-anorectal and lumbo-anorectal and sacro-anorectal motor evoked potentials (MEP) after transcranial and lumbosacral magnetic stimulations, and anorectal manometry before and after six weekly TNT sessions in FI subjects, randomized to 1, 5, or 15 Hz repetitive magnetic stimulations. Neurophysiology, anorectal sensorimotor function, and symptoms were compared to examine mechanistic effects. Co-primary measures were ano-cortical CEPs, cortico-anal MEPs, and lumbosacral-anal MEPs. Baseline and post-treatment data were compared with Wilcoxon signed-rank test and changes between the three frequencies with one-way ANOVA.

RESULTS

Thirty-three FI patients participated. After TNT, the afferent anal CEP latencies significantly decreased in the 1 Hz group compared to baseline (p = 0.0029) and 5 Hz or 15 Hz groups (p = 0.032). Cortico-anal MEPs were unchanged in all three groups. Bilateral lumbo-anal and sacro-anal MEP latencies significantly decreased with 1 Hz, lumbo-anal with 15 Hz, and sacro-anal with 5 Hz compared to baseline but without group differences. The 1 Hz group showed significant increase in anal squeeze sphincter pressure (p < 0.005) and maximum tolerable volume (p < 0.019) and demonstrated higher FI responder rate (p < 0.04) compared to the other two groups. The MEP responders were significantly correlated with FI responders (p = 0.006) in 1 Hz group.

CONCLUSIONS

TNT significantly improves afferent ano-cortical signaling, efferent lumbo-anal and sacro-anal neuropathy and anorectal sensorimotor function. These neurobiologic effects were most prominent with 1 Hz frequency. TNT improves FI by modifying the underlying pathophysiology possibly through neuromodulation.

Translumbosacral Neuromodulation Therapy for Fecal Incontinence: A Randomized Frequency Response Trial

INTRODUCTION

Treatments for fecal incontinence (FI) remain unsatisfactory because they do not remedy the underlying multifactorial dysfunction(s) including anorectal neuropathy. The aim of this study was to investigate the optimal dose frequency, clinical effects, and safety of a novel treatment, translumbosacral neuromodulation therapy (TNT), aimed at improving neuropathy.

METHODS

Patients with FI were randomized to receive 6 sessions of weekly TNT treatments consisting of 600 repetitive magnetic stimulations over each of 2 lumbar and 2 sacral sites with either 1, 5, or 15 Hz frequency. Stool diaries, FI severity indices, anorectal neurophysiology and sensorimotor function, and quality of life were compared. Primary outcome measure was the change in FI episodes/week. Responders were patients with ≥50% decrease in weekly FI episodes.

RESULTS

Thirty-three patients with FI participated. FI episodes decreased significantly (∆ ±95% confidence interval, 4.2 ± 2.8 (1 Hz); 2 ± 1.7 (5 Hz); 3.4 ± 2.5 (15 Hz); P < 0.02) in all 3 groups when compared with baseline. The 1 Hz group showed a significantly higher (P = 0.04) responder rate (91 ± 9.1%) when compared with the 5 Hz group (36 ± 18.2%) or 15 Hz (55 ± 18.2%); no difference was found between the 5 and 15 Hz groups (P = 0.667). Anal neuropathy, squeeze pressure, and rectal capacity improved significantly only in the 1 Hz (P < 0.05) group compared with baseline, but not in other groups. Quality of life domains improved significantly (P < 0.05) with 1 and 5 Hz groups. No device-related serious adverse events were noted.

DISCUSSION

TNT significantly improves FI symptoms in the short term, and the 1 Hz frequency was overall better than 5 and 15 Hz. Both anorectal neuropathy and physiology significantly improved, demonstrating mechanistic improvement. TNT is a promising, novel, safe, efficacious, and noninvasive treatment for FI (see Visual Abstract, Supplementary Digital Content 3, http://links.lww.com/AJG/B598).

Assessing Anorectal Function in Constipation and Fecal Incontinence

Constipation and fecal incontinence are commonly encountered complaints in the gastrointestinal clinic. Assessment of anorectal function includes comprehensive history, rectal examination, and prospective stool diary or electronic App diary that accurately captures bowel symptoms, evaluation of severity, and quality of life of measure. Evaluation of a suspected patient with dyssynergic constipation includes anorectal manometry, balloon expulsion test, and defecography. Investigation of a suspected patient with fecal incontinence includes high-resolution anorectal manometry; anal ultrasound or MRI; and neurophysiology tests, such as translumbosacral anorectal magnetic stimulation or pudendal nerve latency. This article provides an approach to the assessment of anorectal function.

A Novel High-Density Electromyography Probe for Evaluating Anorectal Neurophysiology: Design, Human Feasibility Study, and Validation with Trans-Sacral Magnetic Stimulation

Fecal incontinence (FI) substantially impairs quality of life and imparts a major socioeconomic burden. Anal sphincter injury and possibly pudendal nerve damage are considered common causes, however, current clinical methods for evaluating their function remain suboptimal. Electromyography (EMG) and pudendal nerve terminal latencies have been applied with some success, but are not considered standard practice due to uncertain accuracy and clinical value. In this study we developed and applied a novel anorectal high-density (HD) EMG probe in humans and pigs to acquire quantitative electrophysiological metrics of the anorectum. In the human trial we assessed somatic pathways and showed that EMG amplitude was greater for tight voluntary squeezes than light voluntary squeezes (0.03 ± 0.02 mV vs. 0.05 ± 0.03 mV). In a porcine model we applied trans-sacral magnetic stimulation to evoke extrinsically activated involuntary pathways and the resulting motor evoked potentials (MEP) were captured using the HD-EMG probe. The mean MEP amplitude at 50% magnetic stimulation intensity output (MSO) was significantly lower that the MEP amplitude at 85, 95 and 100% MSO (1.52 ± 0.50 mV vs. 3.10 ± 0.60 mV). In conclusion, the use of HD-EMG probe in conjunction with trans-sacral magnetic stimulation, for spatiotemporal mapping of anorectal EMG and MEP activity is anticipated to achieve new insights into FI and could offer improved diagnostic and prognostic biomarkers for anorectal dysfunction.

A novel combined anorectal biofeedback and percutaneous tibial nerve stimulation protocol for treating fecal incontinence

BACKGROUND/AIMS

Fecal incontinence (FI) is a common, debilitating condition that causes major impact on quality of life for those affected. Non-surgical treatment options include anorectal biofeedback therapy (BF) and percutaneous tibial nerve stimulation (PTNS), usually performed separately. The aims of the current study were to determine the feasibility, tolerability, safety, and efficacy of performing a combined BF and PTNS treatment protocol.

METHODS

Female patients with urge FI were offered a novel pilot program combining BF with PTNS. The treatment protocol consisted of 13 weekly sessions: an educational session, followed by 5 combined BF and PTNS sessions, 6 PTNS and a final combined session. Anorectal physiology and clinical outcomes were assessed throughout the program. For efficacy, patients were compared with BF only historical FI patients matched for age, parity, and severity of symptoms.

RESULTS

A total of 12/13 (93%) patients completed the full program. Overall attendance rate was 93% (157/169 sessions). Patient comfort score with treatment was rated high at 9.8/10 (SD 0.7) for PTNS and 8.6/10 (SD 1.7) for the BF component. No major side effects were reported. A reduction of at least 50% in FI episodes/week was achieved by 58% of patients by visit 6, and 92% by visit 13. No physiology changes were evident immediately following PTNS compared with before, but pressure during sustained anal squeeze improved by the end of the treatment course. Comparing outcomes with historical matched controls, reductions in weekly FI episodes were more pronounced in the BF only group at visit 6, but not week 13.

CONCLUSIONS

In this pilot study, concurrent PTNS and anorectal biofeedback therapy has been shown to be feasible, comfortable, and low risk. The combined protocol is likely to be an effective treatment for FI, but future research could focus on optimizing patient selection.

Randomised clinical trial: linaclotide vs placebo-a study of bi-directional gut and brain axis

BACKGROUND

Linaclotide, a guanylate cyclase C agonist relieves irritable bowel syndrome with predominant constipation (IBS-C) symptoms, but how it improves pain in humans is unknown.

AIMS

To investigate the effects of linaclotide and placebo on the afferent and efferent gut-brain-gut signalling in IBS-C patients, in a randomised clinical trial.

METHODS

Patients with IBS-C (Rome III) and rectal hypersensitivity were randomised (2:1) to receive linaclotide (290 µg) or placebo for 10 weeks and undergo bi-directional gut and brain axis assessment using anorectal electrical stimulations and transcranial/transspinal-anorectal magnetic stimulations. Rectal sensations were examined by balloon distention. Assessments included abdominal pain, bowel symptoms and quality of life (QOL) scores. Primary outcomes were latencies of recto-cortical and cortico-rectal evoked potentials.

RESULTS

Thirty-nine patients participated; 26 received linaclotide and 13 received placebo. Rectal cortical evoked potentials latencies (milliseconds) were significantly prolonged with linaclotide compared to baseline (P1:Δ 19 ± 6, P < 0.005; N1:Δ 20 ± 7, P < 0.02) but not with placebo (P1:Δ 3 ± 5; N1:Δ 4.7 ± 5,P = 0.3) or between groups. The efferent cortico-anorectal and spino-anorectal latencies were unchanged. The maximum tolerable rectal volume (cc) increased significantly with linaclotide compared to baseline (P < 0.001) and placebo (Δ 29 ± 10 vs 4 ± 20, (P < 0.03). Abdominal pain decreased (P < 0.001) with linaclotide but not between groups. Complete spontaneous bowel movement frequency increased (P < 0.001), and IBS-QOL scores improved (P = 0.01) with linaclotide compared to baseline and placebo. There was no difference in overall responders between linaclotide and placebo (54% vs 23%, P = 0.13).

CONCLUSIONS

Linaclotide prolongs afferent gut-brain signalling from baseline but both afferent and efferent signalling were unaffected compared to placebo. Linaclotide significantly improves rectal hypersensitivity, IBS-C symptoms and QOL compared to placebo. These mechanisms may explain the effects of linaclotide on pain relief in IBS-C patients. ClinicalTrials.Gov: Registered at Clinical trials.gov no NCT02078323.

Epidemiologic Trends and Diagnostic Evaluation of Fecal Incontinence

Fecal incontinence (FI) is a prevalent condition that occurs in up to 15% of the Western population and significantly impairs quality of life. The current understanding of the epidemiology of FI is shifting because of an increasing recognition of FI in men, better appreciation for the impact of changing obstetric practices on FI in women, and comprehension of the effect of modifiable risk factors on the development of FI over time. The pathophysiology of FI is complex and multifactorial, which necessitates the use of multiple diagnostic tests, including tests of anorectal sensorimotor function, peripheral nerve function, and anatomic structure. Translumbosacral anorectal magnetic stimulation is an emerging noninvasive diagnostic test for assessing lumbosacral neuropathy. This article is not intended as a comprehensive recitation of the literature, but rather focuses on recent developments in the understanding of the epidemiology of FI, as well as on the diagnostic evaluation of this condition. This article aims to increase awareness of FI and to outline an initial diagnostic approach to affected patients.

Current perspectives on the diagnosis and management of functional anorectal disorders in patients with inflammatory bowel disease

Despite advances in inflammatory bowel disease (IBD) therapies, a significant proportion of patients with quiescent disease experience persistent, debilitating symptoms of faecal incontinence (FI), urgency and defaecatory disorders due to anorectal dysfunction. Such symptoms are often underreported or misdiagnosed and can lead to potentially premature treatment 'escalation' and under-utilisation of pelvic floor investigations. In this review article, we consider putative pathophysiological post-inflammatory changes resulting in altered anorectal sensitivity, motility and neuromuscular coordination and how this may drive symptoms in quiescent IBD. Finally, we discuss a pragmatic approach to investigating and managing anorectal dysfunction and highlight areas for future research for this often-neglected group of patients.