Colonic motor abnormalities in slow transit constipation defined by high resolution, fibre-optic manometry

Ingesting yeast extract causes excitation of neurogenic and myogenic colonic motor patterns in the rat

Fermented foods play a significant role in the human diet for their natural, highly nutritious and healthy attributes. Our aim was to study the effect of yeast extract, a fermented substance extracted from natural yeast, on colonic motility to better understand its potential therapeutic role. A yeast extract was given to rats by gavage for 3 days, and myogenic and neurogenic components of colonic motility were studied using spatiotemporal maps made from video recordings of the whole colon ex vivo. A control group received saline gavages. The yeast extract caused excitation of the musculature by increasing the propagation length and duration of long-distance contractions, the major propulsive activity of the rat colon. The yeast extract also evoked rhythmic propulsive motor complexes (RPMCs) which were antegrade in the proximal and mid-colon and retrograde in the distal colon. RPMC activity was evoked by distention-induced neural activity, but it was myogenic in nature since we showed it to be generated by bethanechol in the presence of tetrodotoxin. In conclusion, ingestion of yeast extract stimulates rat colon motility by exciting neurogenic and myogenic control mechanisms.

The probiotic fermented milk of Lacticaseibacillus paracasei JY062 and Lactobacillus gasseri JM1 alleviates constipation via improving gastrointestinal motility and gut microbiota

Constipation is directly related to the intestinal microenvironment, in which the promotion of gastrointestinal (GI) motility and improvement of gut microbiota distribution are important for alleviating symptoms. Herein, after the intervention of probiotic fermented milk (FMMIX) containing Lacticaseibacillus paracasei JY062 and Lactobacillus gasseri JM1 for 14 d in Kunming mice with loperamide-induced constipation, the results indicated that FMMIX significantly increased the secretion of serum motilin, gastrin and 5-hydroxytryptamine, as well as decreased the secretion of peptide YY, vasoactive intestinal peptide, and nitric oxide in mice. As determined by immunohistochemical analysis, FMMIX promoted an augmentation in the quantity of Cajal interstitial cells. In addition, the mRNA and protein expression of c-kit and stem cell factor (SCF) were upregulated to facilitate intestinal motility. High-throughput sequencing and gas chromatography techniques revealed that FMMIX led to an increase in the relative abundance of beneficial bacteria (Lactobacillus, Oscillospira, Ruminococcus, Coprococcus, and Akkermansia), reduced the presence of harmful bacteria (Prevotella), and resulted in elevated levels of short-chain fatty acids (SCFA) with a superior improvement compared with unfermented milk. Untargeted metabolomics revealed significant upregulation of functional metabolites such as l-pipecolinic acid, dl-phenylalanine, and naringenin in FMMIX, presumably playing a potential role in constipation relief. Overall, our results showed that FMMIX had the potential to alleviate constipation symptoms in mice by improving the secretion of serum GI regulatory peptides and neurotransmitters, increasing the expression of c-kit and SCF proteins, and modulating the gut microbiota structure and SCFA levels, and may be associated with an increase in these functional metabolites. This suggested that FMMIX could be a promising adjunctive strategy for managing constipation symptoms and could contribute to the development of functional foods aimed at improving gut health.

Mechanisms underlying the laxative effect of lactulose: A randomized placebo-controlled trial showing increased small bowel water and motility unaltered by the 5-HT3 receptor antagonist, ondansetron

BACKGROUND

Lactulose is a laxative which accelerates transit and softens stool. Our aim was to investigate its mechanism of action and use this model of diarrhea to investigate the anti-diarrheal actions of ondansetron.

METHODS

A double-blind, randomized, placebo-controlled crossover study of the effect of ondansetron 8 mg in 16 healthy volunteers. Serial MRI scans were performed fasted and 6 h after a meal. Participants then received lactulose 13.6 g twice daily and study drug for a further 36 h. On Day 3, they had further serial MRI scans for 4 h. Measurements included small bowel water content (SBWC), colonic volume, colonic gas, small bowel motility, whole gut transit, and ascending colon relaxation time (T1AC), a measure of colonic water content.

KEY RESULTS

Lactulose increased area under the curve (AUC) of SBWC from 0 to 240 min, mean difference 14.2 L · min (95% CI 4.1, 24.3), p = 0.009, and substantially increased small bowel motility after 4 h (mean (95% CI) 523 (457-646) a.u. to 852 (771-1178) a.u., p = 0.007). There were no changes in T1AC after 36 h treatment. Ondansetron did not significantly alter SBWC, small bowel motility, transit, colonic volumes, colonic gas nor T1AC, with or without lactulose.

CONCLUSION & INFERENCES

Lactulose increases SBWC and stimulates small bowel motility; however, unexpectedly it did not significantly alter colonic water content, suggesting its laxative effect is not osmotic but due to stimulation of motility. Ondansetron's lack of effect on intestinal water suggests its anti-diarrheal effect is not due to inhibition of secretion but more likely altered colonic motility.

Effectiveness, safety and cost-effectiveness of sacral neuromodulation for idiopathic slow-transit constipation: a systematic review

AIM

Sacral neuromodulation (SNM) is a minimally invasive treatment option for functional constipation. Evidence regarding its effectiveness is contradictory, driven by heterogeneous study populations and designs. The aim of this study was to assess the effectiveness, safety and cost-effectiveness of SNM in children and adults with refractory idiopathic slow-transit constipation (STC).

METHOD

OVID Medline, OVID Embase, Cochrane Library, the KSR Evidence Database, the NHS Economic Evaluation Database and the International HTA Database were searched up to 25 May 2023. For effectiveness outcomes, randomized controlled trials (RCTs) were selected. For safety outcomes, all study designs were selected. For cost-effectiveness outcomes, trial- and model-based economic evaluations were selected for review. Study selection, risk of bias and quality assessment, and data extraction were independently performed by two reviewers. For the intervention 'sacral neuromodulation' effectiveness outcomes included defaecation frequency and constipation severity. Safety and cost-effectiveness outcomes were, respectively, adverse events and incremental cost-effectiveness ratios.

RESULTS

Of 1390 records reviewed, 67 studies were selected for full-text screening. For effectiveness, one cross-over and one parallel-group RCT was included, showing contradictory results. Eleven studies on safety were included (four RCTs, three prospective cohort studies and four retrospective cohort studies). Overall infection rates varied between 0% and 22%, whereas reoperation rates varied between 0% and 29%. One trial-based economic evaluation was included, which concluded that SNM was not cost-effective compared with personalized conservative treatment at a time horizon of 6 months. The review findings are limited by the small number of available studies and the heterogeneity in terms of study populations, definitions of refractory idiopathic STC and study designs.

CONCLUSION

Evidence for the (cost-)effectiveness of SNM in children and adults with refractory idiopathic STC is inconclusive. Reoperation rates of up to 29% were reported.

Validation of body surface colonic mapping (BSCM) against high resolution colonic manometry for evaluation of colonic motility

Abnormal cyclic motor pattern (CMP) activity is implicated in colonic dysfunction, but the only tool to evaluate CMP activity, high-resolution colonic manometry (HRCM), remains expensive and not widely accessible. This study aimed to validate body surface colonic mapping (BSCM) through direct correlation with HRCM. Synchronous meal-test recordings were performed in asymptomatic participants with intact colons. A signal processing method for BSCM was developed to detect CMPs. Quantitative temporal analysis was performed comparing the meal responses and motility indices (MI). Spatial heat maps were also compared. Post-study questionnaires evaluated participants' preference and comfort/distress experienced from either test. 11 participants were recruited and 7 had successful synchronous recordings (5 females/2 males; median age: 50 years [range 38-63]). The best-correlating MI temporal analyses achieved a high degree of agreement (median Pearson correlation coefficient (Rp) value: 0.69; range 0.47-0.77). HRCM and BSCM meal response start and end times (Rp = 0.998 and 0.83; both p < 0.05) and durations (Rp = 0.85; p = 0.03) were similar. Heat maps demonstrated good spatial agreement. BSCM is the first non-invasive method to be validated by demonstrating a direct spatio-temporal correlation to manometry in evaluating colonic motility.

Abnormal gastrointestinal motility is a major factor in explaining symptoms and a potential therapeutic target in patients with disorders of gut-brain interaction

The objective of this article is to review the evidence of abnormal gastrointestinal (GI) tract motor functions in the context of disorders of gut-brain interaction (DGBI). These include abnormalities of oesophageal motility, gastric emptying, gastric accommodation, colonic transit, colonic motility, colonic volume and rectal evacuation. For each section regarding GI motor dysfunction, the article describes the preferred methods and the documented motor dysfunctions in DGBI based on those methods. The predominantly non-invasive measurements of gut motility as well as therapeutic interventions directed to abnormalities of motility suggest that such measurements are to be considered in patients with DGBI not responding to first-line approaches to behavioural or empirical dietary or pharmacological treatment.

Characteristics of the Cajal interstitial cells and intestinal microbiota in children with refractory constipation

BACKGROUND

Children with refractory constipation experience intense and persistent symptoms that greatly diminish their quality of life. However, the underlying pathophysiological mechanism responsible for this condition remains uncertain. Our objective was to evaluate characteristics of colonic motor patterns and interstitial cells of Cajal (ICCs) to refractory constipation children, as well as intestinal microbiota compositions.

METHODS

Colonic manometry (CM) was conducted on a cohort of 30 patients with refractory constipation to assess colonic motility, and 7 of them underwent full-thickness colon biopsy specimens. Another 5 colonic specimens from nonconstipation patients were collected to identify the ICCs by immunohistochemistry. Fecal samples from 14 children diagnosed with refractory constipation and subjecting 28 age-matched healthy children to analysis using high-throughput sequencing of 16S rRNA.

RESULTS

According to CM results, dividing 30 children with refractory constipation into 2 groups: normal group (n = 10) and dysmotility group (n = 20). Dysmotility subjects showed lower colonic motility. Antegrade propagating pressure waves, retrograde propagating pressure waves, and periodic colonic motor activity were common in normal subjects and rare in dysmotility subjects (32.7 ± 8.9 vs 20.7 ± 13.0/17 h, P < 0.05, 11.5 ± 2.3 vs 9.6 ± 2.3/17 h, P < 0.05, and 5.2 ± 8.9 vs 3.5 ± 6.8 cpm, P < 0.005, respectively), whereas periodic rectal motor activity was more common in dysmotility subjects (3.4 ± 4.8 vs 3.0 ± 3.1 cpm, P < 0.05). Dysmotility subjects exhibited a significantly greater number of preprandial simultaneous pressure waves compared to the normal subjects (32.3 ± 25.0 vs 23.6 ± 13.2/1 h, P < 0.005). Dysmotility subjects displayed a notable decrease in postprandial count of antegrade propagating pressure waves and high amplitude propagating pressure waves when compared to normal subjects (3.9 ± 2.9 vs 6.9 ± 3.5/1 h and 2.3 ± 1.5 vs 5.4 ± 2.9/1 h, respectively, P < 0.05). The number, distribution, and morphology of ICCs were markedly altered in refractory constipation compared children to the controls (P < 0.05). Children diagnosed with refractory constipation displayed a distinct dissimilarity in composition of their intestinal microbiota comparing with control group (P < 0.005). In genus level, Bacteroidetes represented 34.34% and 43.78% in the refractory constipation and control groups, respectively. Faecalibacterium accounted for 3.35% and 12.56%, respectively (P < 0.005). Furthermore, the relative abundances of Faecalibacterium (P < 0.005), Lachnospira (P < 0.05), and Haemophilus (P < 0.05) significantly decreased, whereas those of Parabacteroides (P < 0.05), Alistipes (P < 0.005), Prevotella_2 (P < 0.005), [Ruminococcus]_torques_group (P < 0.005), Barnesiella (P < 0.05), Ruminococcaceae_UCG-002 (P < 0.005), and Christensensenellaceae_R-7_group (P < 0.05) were markedly increased in children with refractory constipation.

CONCLUSIONS

Dysmotility subjects showed lower colonic motility and an impaired postprandial colonic response. The decreased number and abnormal morphology of colonic ICCs may contribute to the pathogenesis of refractory constipation. Children with refractory constipation exhibited significant variations in microbiota composition across various taxonomic levels compared to the healthy control group. Our findings contribute valuable insights into pathophysiological mechanism underlying refractory constipation and provide evidence to support the exploration of novel therapeutic strategies for affected children.

Haustral rhythmic motor patterns of the human large bowel revealed by ultrasound

Effective and widely available strategies are needed to diagnose colonic motility dysfunction. We investigated whether ultrasonography could generate spatiotemporal maps combined with motor pattern frequency analysis, to become a noninvasive method to characterize human colon motor patterns. Abdominal colonic ultrasonography was performed on healthy subjects (N = 7), focusing on the detailed recording of spontaneous haustral activities. We developed image segmentation and frequency analysis software to analyze the motor patterns captured. Ultrasonography recordings of the ascending, transverse, and descending colon identified three distinct rhythmic motor patterns: the 1 cycle/min and the 3 cycles/min cyclic motor pattern were seen throughout the whole colon, whereas the 12 cycles/min cyclic motor pattern was identified in the ascending colon. The rhythmic motor patterns of the human colon that are associated with interstitial cells of Cajal-associated pacemaking activity can be accurately identified and quantified using ultrasound.NEW & NOTEWORTHY Ultrasonography in the clinical field is an underutilized tool for assessing colonic motility; however, with the addition of frequency analysis techniques, it provides a method to identify human colonic motor patterns. Here we report on the 1, 3, and 12 cpm rhythmic motor patterns. Ultrasound has the potential to become a bedside assessment for colonic dysmotility and may reveal the health of interstitial cells of Cajal (ICC) pacemaker activities.

Subtyping intractable functional constipation in children using clinical and laboratory data in a classification model

Background

Children with intractable functional constipation (IFC) who are refractory to traditional pharmacological intervention develop severe symptoms that can persist even in adulthood, resulting in a substantial deterioration in their quality of life. In order to better manage IFC patients, efficient subtyping of IFC into its three subtypes, normal transit constipation (NTC), outlet obstruction constipation (OOC), and slow transit constipation (STC), at early stages is crucial. With advancements in technology, machine learning can classify IFC early through the use of validated questionnaires and the different serum concentrations of gastrointestinal motility-related hormones.

Method

A hundred and one children with IFC and 50 controls were enrolled in this study. Three supervised machine-learning methods, support vector machine, random forest, and light gradient boosting machine (LGBM), were used to classify children with IFC into the three subtypes based on their symptom severity, self-efficacy, and quality of life which were quantified using certified questionnaires and their serum concentrations of the gastrointestinal hormones evaluated with enzyme-linked immunosorbent assay. The accuracy of machine learning subtyping was evaluated with respect to radiopaque markers.

Results

Of 101 IFC patients, 37 had NTC, 49 had OOC, and 15 had STC. The variables significant for IFC subtype classification, according to SelectKBest, were stool frequency, the satisfaction domain of the Patient Assessment of Constipation Quality of Life questionnaire (PAC-QOL), the emotional self-efficacy for Functional Constipation questionnaire (SEFCQ), motilin serum concentration, and vasoactive intestinal peptide serum concentration. Among the three models, the LGBM model demonstrated an accuracy of 83.8%, a precision of 84.5%, a recall of 83.6%, a f1-score of 83.4%, and an area under the receiver operating characteristic curve (AUROC) of 0.89 in discriminating IFC subtypes.

Conclusion

Using clinical characteristics measured by certified questionnaires and serum concentrations of the gastrointestinal hormones, machine learning can efficiently classify pediatric IFC into its three subtypes. Of the three models tested, the LGBM model is the most accurate model for the classification of IFC, with an accuracy of 83.8%, demonstrating that machine learning is an efficient tool for the management of IFC in children.

Association of sleep duration with chronic constipation among adult men and women: Findings from the National Health and Nutrition Examination Survey (2005-2010)

Background

Previous studies suggested that unhealthy sleep patterns were closely associated with gastrointestinal diseases, but the impact of unhealthy sleep duration on chronic constipation has not been well studied until now. In this study, we aim to explore the association between sleep duration and constipation among males and females.

Methods

We utilized the US National Health and Nutrition Examination Surveys data from 2005 to 2010, and adults (≥20 years old) who completed the sleep and bowel health questionnaires were enrolled in this observational study. Sleep duration was categorized into four groups: very short sleep (<5 h/night), short sleep (5-6 h/night), normal sleep (7-8 h/night), and long sleep (≥9 h/night). Chronic constipation was defined as Bristol Stool Scale Type 1(separate hard lumps, like nuts) or Type 2(sausage-like but lumpy). Controlling demographic, lifestyle, and dietary factors, the logistic regression model in Generalized Linear Model (GLM) function was used to estimate the correlation of sleep duration with constipation among men and women.

Results

Of the 11,785 individuals (51.2% males and 48.8% females), 4.3% of men and 10.2% of women had constipation, respectively. More than half of patients with constipation did not adopt the recommended sleep duration. Compared with normal individuals, male participants with constipation had a higher proportion of shorter sleep duration (41.0 vs. 32.3% in the short sleep group and 6.3 vs. 4.7% in the very short sleep group), and female individuals with constipation had a higher proportion of long sleep duration (12.7 vs. 8.2%). After covariates adjustment, men with short sleep duration (5-6 h/night) correlated with increased odds for constipation (OR:1.54, 95%CI:1.05-2.25), and women with long sleep duration (≥9 h/night) linked to the higher constipation risk (OR:1.58, 95%CI:1.10-2.29). Excessive sleep duration in males or insufficient sleep duration in females was neither linked to increased nor decreased constipation risk.

Conclusions

In this observational study of a nationally representative sample of adults, we demonstrate a differential impact of unhealthy sleep duration on constipation among men and women. Short sleep duration poses a higher risk of constipation in men, and excessive sleep duration correlates with higher constipation risk in women.

Diagnosis of colonic dysmotility associated with autonomic dysfunction in patients with chronic refractory constipation

We report the first study assessing human colon manometric features and their correlations with changes in autonomic functioning in patients with refractory chronic constipation prior to consideration of surgical intervention. High-resolution colonic manometry (HRCM) with simultaneous heart rate variability (HRV) was performed in 14 patients, and the resulting features were compared to healthy subjects. Patients were categorized into three groups that had normal, weak, or no high amplitude propagating pressure waves (HAPWs) to any intervention. We found mild vagal pathway impairment presented as lower HAPW amplitude in the proximal colon in response to proximal colon balloon distention. Left colon dysmotility was observed in 71% of patients, with features of (1) less left colon HAPWs, (2) lower left colon HAPW amplitudes (69.8 vs 102.3 mmHg), (3) impaired coloanal coordination, (4) left colon hypertonicity in patients with coccyx injury. Patients showed the following autonomic dysfunction: (1) high sympathetic tone at baseline, (2) high sympathetic reactivity to active standing and meal, (3) correlation of low parasympathetic reactivity to the meal with absence of the coloanal reflex, (4) lower parasympathetic and higher sympathetic activity during occurrence of HAPWs. In conclusion, left colon dysmotility and high sympathetic tone and reactivity, more so than vagal pathway impairment, play important roles in refractory chronic constipation and suggests sacral neuromodulation as a possible treatment.

Association of Dietary Energy Intake With Constipation Among Men and Women: Results From the National Health and Nutrition Examination Survey

Background

Previous studies supported that dietary factor was associated with constipation, but the relationship between dietary energy intake and constipation has not been well-studied. Therefore, we aimed to evaluate the prevalence and correlation between energy intake and constipation among men and women.

Methods

These observational analyses included 12,587 adults (≥20 years) from the 2005–2010 cycles of the National Health and Nutrition Examination Surveys (NHANES). Constipation was defined as Bristol Stool Scale Type 1 (separate hard lumps, like nuts) or Type 2 (sausage-like but lumpy). Total energy intake was obtained from the two 24-h dietary recalls and averaged. We used the logistic regression model in Generalized Linear Model (GLM) function, controlling demographic, lifestyle, and dietary factors, to estimate the association between energy intake and constipation among men and women.

Results

The overall weighted incidence of constipation in this research was 7.4%, the incidence in women and men was 10.4 and 4.3%, respectively. After multivariable adjustment, middle energy consumption correlated with decreased risk of constipation in men (OR:0.5, 95% CI:0.29–0.84), and lower-middle energy intake increased the constipation risk in women (OR: 1.56, 95% CI: 1.15–2.13). High energy consumption was not associated with increased or decreased constipation risk.

Conclusions

To our knowledge, this is the first research to investigate the association between energy intake and constipation; the study demonstrates that appropriate energy consumption can help reduce the risk of constipation in men, and relatively low energy intake is associated with increased constipation risk in women.

DIAGNOSIS AND MANAGEMENT OF CHRONIC IDIOPATHIC CONSTIPATION: A NARRATIVE REVIEW FROM A BRAZILIAN EXPERT TASK FORCE

ABSTRACT Background Chronic idiopathic constipation (CIC) is a condition that widely affects the global population, represents relevant healthcare resource utilization and costs, and impacts the individual’s well-being. Objective To review the consensus of expert societies and published guidelines on the diagnosis and treatment of CIC in adults, seeking to assist reasoning and decision-making for medical management of patients with CIC and provide a practical reference material. Methods A Brazilian medical task force searched the scientific literature in the following electronic databases: MEDLINE/PubMed, SciELO, EMBASE and Cochrane, using the following descriptors: chronic constipation, diagnosis, management of chronic constipation. In addition, a review of articles on the mechanism of action, safety, and efficacy of therapeutic options available in Brazil was carried out. Results The diagnostic approach and the understanding of the pathophysiology present in CIC are essential items to indicate the appropriate therapy and to understand the ecosystem of the patient’s needs. Conclusion CIC is a common condition in adults, occurring more frequently in the elderly and in women. Proper management is defined by detailed medical history and physical examination, together with appropriate therapeutics, regardless pharmacological or not, and depending on the best moment of indication. This way, the impact on quality of life is also optimized.

Probiotics and Functional Gastrointestinal Disorders in Pediatric Age: A Narrative Review

Assessment and management of pain are essential components of pediatric care. Pain in pediatric age is characterized by relevant health and socio-economic consequences due to parental concern, medicalization, and long-term physical and psychological impact in children. Pathophysiological mechanisms of nociception include several pathways in which also individual perception and gut-brain axis seem to be involved. In this narrative review, we analyze the rational and the current clinical findings of probiotic use in the management of functional gastrointestinal disorders (FGID) in pediatric age, with special focus on infantile colic, irritable bowel syndrome, constipation, and gastroesophageal reflux. Some specific probiotics showed a significant reduction in crying and fussing compared to placebo in breastfed infants with colic, although their exact mechanism of action in this disorder remains poorly understood. In irritable bowel syndrome, a limited number of studies showed that specific strains of probiotics can improve abdominal pain/discomfort and bloating/gassiness, although data are still scarce. As for constipation, whilst some strains appear to reduce the number of hard stools in constipated children, the evidence is not adequate to support the use of probiotics in the management of functional constipation. Similarly, although some probiotic strains could promote gastric emptying with a potential improvement of functional symptoms related to gastroesophageal reflux, current evidence is insufficient to provide any specific recommendation for the prevention or treatment of gastroesophageal reflux. In conclusion, probiotics have been proposed as part of management of pain in functional gastrointestinal disorders in pediatric age, but mechanisms are still poorly understood and evidence to guide clinical practice is currently inadequate.

Interstitial cells of Cajal and human colon motility in health and disease

Our understanding of human colonic motility, and autonomic reflexes that generate motor patterns, has increased markedly through high-resolution manometry. Details of the motor patterns are emerging related to frequency and propagation characteristics that allow linkage to interstitial cells of Cajal (ICC) networks. In studies on colonic motor dysfunction requiring surgery, ICC are almost always abnormal or significantly reduced. However, there are still gaps in our knowledge about the role of ICC in the control of colonic motility and there is little understanding of a mechanistic link between ICC abnormalities and colonic motor dysfunction. This review will outline the various ICC networks in the human colon and their proven and likely associations with the enteric and extrinsic autonomic nervous systems. Based on our extensive knowledge of the role of ICC in the control of gastrointestinal motility of animal models and the human stomach and small intestine, we propose how ICC networks are underlying the motor patterns of the human colon. The role of ICC will be reviewed in the autonomic neural reflexes that evoke essential motor patterns for transit and defecation. Mechanisms underlying ICC injury, maintenance, and repair will be discussed. Hypotheses are formulated as to how ICC dysfunction can lead to motor abnormalities in slow transit constipation, chronic idiopathic pseudo-obstruction, Hirschsprung's disease, fecal incontinence, diverticular disease, and inflammatory conditions. Recent studies on ICC repair after injury hold promise for future therapies.

Intraoperative serosal extracellular mapping of the human distal colon: a feasibility study

BACKGROUND

Cyclic motor patterns (CMP) are the predominant motor pattern in the distal colon, and are important in both health and disease. Their origin, mechanism and relation to bioelectrical slow-waves remain incompletely understood. During abdominal surgery, an increase in the CMP occurs in the distal colon. This study aimed to evaluate the feasibility of detecting propagating slow waves and spike waves in the distal human colon through intraoperative, high-resolution (HR), serosal electrical mapping.

METHODS

HR electrical recordings were obtained from the distal colon using validated flexible PCB arrays (6 × 16 electrodes; 4 mm inter-electrode spacing; 2.4 cm², 0.3 mm diameter) for up to 15 min. Passive unipolar signals were obtained and analysed.

RESULTS

Eleven patients (33-71 years; 6 females) undergoing colorectal surgery under general anaesthesia (4 with epidurals) were recruited. After artefact removal and comprehensive manual and automated analytics, events consistent with regular propagating activity between 2 and 6 cpm were not identified in any patient. Intermittent clusters of spike-like activities lasting 10-180 s with frequencies of each cluster ranging between 24 and 42 cpm, and an average amplitude of 0.54 ± 0.37 mV were recorded.

CONCLUSIONS

Intraoperative colonic serosal mapping in humans is feasible, but unlike in the stomach and small bowel, revealed no regular propagating electrical activity. Although sporadic, synchronous spike-wave events were identifiable. Alternative techniques are required to characterise the mechanisms underlying the hyperactive CMP observed in the intra- and post-operative period.

NEW FINDINGS

The aim of this study was to assess the feasibility of detecting propagating electrical activity that may correlate to the cyclic motor pattern in the distal human colon through intraoperative, high-resolution, serosal electrical mapping. High-resolution electrical mapping of the human colon revealed no regular propagating activity, but does reveal sporadic spike-wave events. These findings indicate that further research into appropriate techniques is required to identify the mechanism of hyperactive cyclic motor pattern observed in the intra- and post-operative period in humans.

The Sphincter of O'Beirne-Part 2: Report of a Case of Chronic Constipation with Autonomous Dyssynergia

BACKGROUND

Chronic constipation can have one or more of many etiologies, and a diagnosis based on symptoms is not sufficient as a basis for treatment, in particular surgery.

AIM

To investigate the cause of chronic constipation in a patient with complete absence of spontaneous bowel movements.

METHODS

High-resolution colonic manometry was performed to assess motor functions of the colon, rectum, the sphincter of O'Beirne and the anal sphincters.

RESULTS

Normal colonic motor patterns were observed, even at baseline, but a prominent high-pressure zone at the rectosigmoid junction, the sphincter of O'Beirne, was consistently present. In response to high-amplitude propagating pressure waves (HAPWs) that were not consciously perceived, the sphincter and the anal sphincters would not relax and paradoxically contract, identified as autonomous dyssynergia. Rectal bisacodyl evoked marked HAPW activity with complete relaxation of the sphincter of O'Beirne and the anal sphincters, indicating that all neural pathways to generate the coloanal reflex were intact but had low sensitivity to physiological stimuli. A retrograde propagating cyclic motor pattern initiated at the sphincter of O'Beirne, likely contributing to failure of content to move into the rectum.

CONCLUSIONS

Chronic constipation without the presence of spontaneous bowel movements can be associated with normal colonic motor patterns but a highly exaggerated pressure at the rectosigmoid junction: the sphincter of O'Beirne, and failure of this sphincter and the anal sphincters to relax associated with propulsive motor patterns. The sphincter of O'Beirne can be an important part of the pathophysiology of chronic constipation.

Luminal Fluid Motion Inside an In Vitro Dissolution Model of the Human Ascending Colon Assessed Using Magnetic Resonance Imaging

Knowledge of luminal flow inside the human colon remains elusive, despite its importance for the design of new colon-targeted drug delivery systems and physiologically relevant in silico models of dissolution mechanics within the colon. This study uses magnetic resonance imaging (MRI) techniques to visualise, measure and differentiate between different motility patterns within an anatomically representative in vitro dissolution model of the human ascending colon: the dynamic colon model (DCM). The segmented architecture and peristalsis-like contractile activity of the DCM generated flow profiles that were distinct from compendial dissolution apparatuses. MRI enabled different motility patterns to be classified by the degree of mixing-related motion using a new tagging method. Different media viscosities could also be differentiated, which is important for an understanding of colonic pathophysiology, the conditions that a colon-targeted dosage form may be subjected to and the effectiveness of treatments. The tagged MRI data showed that the DCM effectively mimicked wall motion, luminal flow patterns and the velocities of the contents of the human ascending colon. Accurate reproduction of in vivo hydrodynamics is an essential capability for a biorelevant mechanical model of the colon to make it suitable for in vitro data generation for in vitro in vivo evaluation (IVIVE) or in vitro in vivo correlation (IVIVC). This work illustrates how the DCM provides new insight into how motion of the colonic walls may control luminal hydrodynamics, driving erosion of a dosage form and subsequent drug release, compared to traditional pharmacopeial methods.

Disruption of Circadian Rhythms and Gut Motility: An Overview of Underlying Mechanisms and Associated Pathologies

Circadian rhythms ensure that physiological processes occur at the most biologically meaningful time. The circadian timing in the gastrointestinal tract involves interlocking transcriptional and translational feedback loops that culminate in the rhythmic expression and activity of a set of clock genes and related hormones. The suprachiasmatic nucleus and peripheral core molecular clocks oscillate every 24 hours and are responsible for the periodic activity of various segments and transit along the gastrointestinal tract. Environmental cues may alter or reset these rhythms to align them with new circumstances. Colonic motility also follows a circadian rhythm with reduced nocturnal activity. Healthy humans have normal bowel motility during the day, frequently following awakening or following a meal, with minimal activity during the night. Maladjusted circadian rhythms in the bowel have been linked to digestive pathologies, including constipation and irritable bowel syndrome. Our advanced knowledge of the link between the circadian clock and gastrointestinal physiology provides potential therapeutic approaches for the treatment of gastrointestinal diseases. This review seeks to establish evidence for the correlation between circadian rhythm, bowel movements and digestive health, and examine the implications of disrupted circadian rhythms on gut physiology.

Chronic constipation in adults: Contemporary perspectives and clinical challenges. 1: Epidemiology, diagnosis, clinical associations, pathophysiology and investigation

BACKGROUND

Chronic constipation is a prevalent disorder that affects patients' quality of life and consumes resources in healthcare systems worldwide. In clinical practice, it is still considered a challenge as clinicians frequently are unsure as to which treatments to use and when. Over a decade ago, a Neurogastroenterology & Motility journal supplement devoted to the investigation and management of constipation was published (2009; 21 (Suppl.2)). This included seven articles, disseminating all themes covered during a preceding 2-day meeting held in London, entitled "Current perspectives in chronic constipation: a scientific and clinical symposium." In October 2018, the 3rd London Masterclass, entitled "Contemporary management of constipation" was held, again over 2 days. All faculty members were invited to author two new review articles, which represent a collective synthesis of talks presented and discussions held during this meeting.

PURPOSE

This article represents the first of these reviews, addressing epidemiology, diagnosis, clinical associations, pathophysiology, and investigation. Clearly, not all aspects of the condition can be covered in adequate detail; hence, there is a focus on particular "hot topics" and themes that are of contemporary interest. The second review addresses management of chronic constipation, covering behavioral, conservative, medical, and surgical therapies.

Control of colonic motility using electrical stimulation to modulate enteric neural activity

Electrical stimulation of the enteric nervous system (ENS) is an attractive approach to modify gastrointestinal transit. Colonic motor complexes (CMCs) occur with a periodic rhythm, but the ability to elicit a premature CMC depends, at least in part, upon the intrinsic refractory properties of the ENS, which are presently unknown. The objectives of this study were to record myoelectric complexes (MCs, the electrical correlates of CMCs) in the smooth muscle and 1) determine the refractory periods of MCs, 2) inform and evaluate closed-loop stimulation to repetitively evoke MCs, and 3) identify stimulation methods to suppress MC propagation. We dissected the colon from male and female C57BL/6 mice, preserving the integrity of intrinsic circuitry while removing the extrinsic nerves, and measured properties of spontaneous and evoked MCs in vitro. Hexamethonium abolished spontaneous and evoked MCs, confirming the necessary involvement of the ENS for electrically evoked MCs. Electrical stimulation reduced the mean interval between evoked and spontaneous CMCs (24.6 ± 3.5 vs. 70.6 ± 15.7 s, P = 0.0002, n = 7). The absolute refractory period was 4.3 s (95% confidence interval (CI) = 2.8-5.7 s, R2 = 0.7315, n = 8). Electrical stimulation applied during fluid distention-evoked MCs led to an arrest of MC propagation, and following stimulation, MC propagation resumed at an increased velocity (n = 9). The timing parameters of electrical stimulation increased the rate of evoked MCs and the duration of entrainment of MCs, and the refractory period provides insight into timing considerations for designing neuromodulation strategies to treat colonic dysmotility.NEW & NOTEWORTHY Maintained physiological distension of the isolated mouse colon induces rhythmic cyclic myoelectric complexes (MCs). MCs evoked repeatedly by closed-loop electrical stimulation entrain MCs more frequently than spontaneously occurring MCs. Electrical stimulation delivered at the onset of a contraction temporarily suppresses the propagation of MC contractions. Controlled electrical stimulation can either evoke MCs or temporarily delay MCs in the isolated mouse colon, depending on timing relative to ongoing activity.

High-Resolution Colonic Manometry Pressure Profiles Are Similar in Asymptomatic Diverticulosis and Controls

BACKGROUND

Elevated colonic pressures and increased colonic activity have been thought to contribute to the pathophysiology of diverticulosis. However, evidence for this has been limited to low-resolution manometry, which is of limited accuracy.

AIMS

This study aimed to evaluate the contraction pressures, counts, and distance of propagation recorded by high-resolution colonic manometry in diverticulosis vs control patients.

METHODS

High-resolution colonic manometry was used to record descending and sigmoid colon activity pre- and post-meal in patients with established, asymptomatic diverticulosis and in healthy controls. Antegrade and retrograde propagating contractions, distance of propagation (mm), and mean contraction pressures (mmHg) in the descending and sigmoid colon were compared between patients and controls for all isolated propagating contractions, the cyclic motor pattern, and high-amplitude propagating contractions independently.

RESULTS

Mean manometry pressures were not different between controls and diverticulosis patients (p > 0.05 for all comparisons). In the descending colon, diverticulosis patients had lower post-meal mean distance of propagation for all propagating contractions [10.8 (SE1.5) mm vs 20.0 (2.0) mm, p = 0.003] and the cyclic motor pattern [6.0 (2.5) mm vs 17.1 (2.8) mm, p = 0.01]. In the sigmoid colon, diverticulosis patients showed lower post-meal mean distance of propagation for all propagating contractions [10.8 (1.5) mm vs 20.2 (5.9) mm, p = 0.01] and a lower post-meal increase in retrograde propagating contractions (p = 0.04).

CONCLUSIONS

In this first high-resolution colonic manometry study of patients with diverticular disease, we did not find evidence for increased manometric pressures or increased colonic activity in patients with diverticular disease.

Automated Analysis Using a Bayesian Functional Mixed-Effects Model With Gaussian Process Responses for Wavelet Spectra of Spatiotemporal Colonic Manometry Signals

Manual analysis of human high-resolution colonic manometry data is time consuming, non-standardized and subject to laboratory bias. In this article we present a technique for spectral analysis and statistical inference of quasiperiodic spatiotemporal signals recorded during colonic manometry procedures. Spectral analysis is achieved by computing the continuous wavelet transform and cross-wavelet transform of these signals. Statistical inference is achieved by modeling the resulting time-averaged amplitudes in the frequency and frequency-phase domains as Gaussian processes over a regular grid, under the influence of categorical and numerical predictors specified by the experimental design as a functional mixed-effects model. Parameters of the model are inferred with Hamiltonian Monte Carlo. Using this method, we re-analyzed our previously published colonic manometry data, comparing healthy controls and patients with slow transit constipation. The output from our automated method, supports and adds to our previous manual analysis. To obtain these results took less than two days. In comparison the manual analysis took 5 weeks. The proposed mixed-effects model approach described here can also be used to gain an appreciation of cyclical activity in individual subjects during control periods and in response to any form of intervention.

Altered colonic motility is associated with low anterior resection syndrome

AIM

Patients frequently suffer from low anterior resection syndrome (LARS) after distal colorectal resection. The pathophysiology of LARS has not been clearly elucidated. We hypothesized that rectosigmoid resection could impair motility patterns in the distal colon, such as the rectosigmoid brake, which contribute to control of stool form and frequency.

METHOD

High-resolution colonic manometry was performed in patients who had previously undergone distal colorectal resection (mean 6.8 years after resection) and non-operative controls before and after a standardized meal. Symptoms were assessed using the LARS score. Propagating contractions were compared between patients with and without LARS, and controls.

RESULTS

Data were analysed from 23 patients (11 no-LARS; 12 LARS) and nine controls. All groups demonstrated a significant meal response. LARS patients had fewer post-prandial antegrade propagating contractions than controls (P = 0.028), and fewer retrograde propagating contractions both pre- (P = 0.005) and post-prandially (P = 0.004). Post-prandially, the LARS group had a significantly lower percentage of propagating contractions that met the criteria for the cyclic motor pattern compared to the control group (26% vs. 58%; P = 0.009). There were significant differences in antegrade and retrograde amplitude (P = 0.049; P = 0.018) and distance of propagation (P = 0.003; P = 0.002) post-prandially between LARS patients and controls.

CONCLUSION

Rectosigmoid resection alters the meal response following anterior resection, including impairment of the rectosigmoid brake cyclic motor pattern. These findings help to quantify the impaired functional motility after rectosigmoid resection and offer new insights into the mechanisms of LARS.

ManoMap: an automated system for characterization of colonic propagating contractions recorded by high-resolution manometry

RATIONALE

Colonic high-resolution manometry (cHRM) is an emerging clinical tool for defining colonic function in health and disease. Current analysis methods are conducted manually, thus being inefficient and open to interpretation bias.

OBJECTIVE

The main objective of the study was to build an automated system to identify propagating contractions and compare the performance to manual marking analysis.

METHODS

cHRM recordings were performed on 5 healthy subjects, 3 subjects with diarrhea-predominant irritable bowel syndrome, and 3 subjects with slow transit constipation. Two experts manually identified propagating contractions, from five randomly selected 10-min segments from each of the 11 subjects (72 channels per dataset, total duration 550 min). An automated signal processing and detection platform was developed to compare its effectiveness to manually identified propagating contractions. In the algorithm, individual pressure events over a threshold were identified and were then grouped into a propagating contraction. The detection platform allowed user-selectable thresholds, and a range of pressure thresholds was evaluated (2 to 20 mmHg).

KEY RESULTS

The automated system was found to be reliable and accurate for analyzing cHRM with a threshold of 15 mmHg, resulting in a positive predictive value of 75%. For 5-h cHRM recordings, the automated method takes 22 ± 2 s for analysis, while manual identification would take many hours.

CONCLUSIONS

An automated framework was developed to filter, detect, quantify, and visualize propagating contractions in cHRM recordings in an efficient manner that is reliable and consistent.

Distinct patterns of myogenic motor activity identified in isolated human distal colon with high-resolution manometry

BACKGROUND

Colonic high-resolution manometry (HRM) has been used to reveal discrete, propagating colonic motor patterns. To help determine mechanisms underlying these patterns, we used HRM to record contractile activity in human distal colon ex vivo.

METHODS

Surgically excised segments of descending (n = 30) or sigmoid colon (n = 4) were immersed in oxygenated Krebs solution at 36°C (n = 34; 16 female; 67.6 ± 12.4 years; length: 24.7 ± 3.5 cm). Contractility was recorded by HRM catheters. After 30 minutes of baseline recording, 0.3 mM lidocaine and/or 1 mM hexamethonium were applied. Ascending neural pathways were activated by electrical field stimulation (EFS; 10 Hz, 0.5 ms, 50 V, 5-s duration) applied to the anal end before and after drug application.

RESULTS

Spontaneous propagating contractions were recorded in all specimens (0.1-1.5 cycles/minute). Most contractions occurred synchronously across all recording sites. In five specimens, rhythmic antegrade contractions propagated across the full length of the preparation. EFS evoked local contractions at the site of stimulation (latency: 5.5 ± 2.4 seconds) with greater amplitude than spontaneous contractions (EFS; 29.3 ± 26.9 vs 12.1 ± 14.8 mm Hg; P = .02). Synchronous or retrograde propagating motor patterns followed EFS; 71% spanned the entire preparation length. Hexamethonium and lidocaine modestly and only temporarily inhibited spontaneous contractions, whereas TTX increased the frequency of contractile activity while inhibiting EFS-evoked contractions.

CONCLUSIONS AND INFERENCES

Our study suggests that the propagated contractions recorded in the organ bath have a myogenic origin which can be regulated by neural input. Once activated at a local site, the contractions do not require the propulsion of fecal content to sustain long-distance propagation.

Novel insight into pressurization of the male and female urethra through application of a multi-channel fibre-optic pressure transducer: Proof of concept and validation

Purpose

To confirm feasibility of recording pressure along the length of the urethra using a multi-sensor fibre-optic pressure catheter; to identify the spatial and temporal features of changes in pressure along the urethra at sites related to specific striated pelvic floor muscles; and to investigate the relationship between urethral pressures and activation of individual pelvic floor muscles estimated from ultrasound imaging.

Materials and Methods

Proof-of-concept study including one male (47 years old) and one female (33 years old). A multi-sensor fibre optic pressure catheter (10 mm sensor separation) was inserted into the urethra. Pressure data were recorded simultaneously with trans-perineal ultrasound imaging measures of pelvic floor muscle activity during sub-maximal and maximal voluntary contractions and evoked coughs.

Results

Pressure changes along the urethra were recorded in all tasks in both participants. Face validity of interpretation of pressure measures with respect to individual muscles was supported by correlation with ultrasound-measured displacements induced by the relevant muscles. Onset of pressure increase occurred in a distal to proximal sequence in the urethra of the male but not the female during voluntary contraction. Peak urethral pressures varied in location, timing and amplitude between tasks. Evoked cough induced in the greatest urethral pressure increase across all tasks for both participants.

Conclusions

The high spatial resolution pressure catheter provide viable and valid recordings of urethral pressure in a male and female. Data provide preliminary evidence of sex differences in spatial and temporal distribution of urethral pressure changes.

The cyclic motor patterns in the human colon

BACKGROUND

High-resolution colonic manometry gives an unprecedented window into motor patterns of the human colon. Our objective was to characterize motor activities throughout the entire colon that possessed persistent rhythmicity and spanning at least 5 cm.

METHODS

High-resolution colonic manometry using an 84-channel water-perfused catheter was performed in 19 healthy volunteers. Rhythmic activity was assessed during baseline, proximal balloon distention, meal, and bisacodyl administration.

KEY RESULTS

Throughout the entire colon, a cyclic motor pattern occurred either in isolation or following a high-amplitude propagating pressure wave (HAPW), consisting of clusters of pressure waves at a frequency centered on 11-13 cycles/min, unrelated to breathing. The cluster duration was 1-6 minutes; the pressure waves traveled for 8-27 cm, lasting 5-8 seconds. The clusters itself could be rhythmic at 0.5-2 cpm. The propagation direction of the individual pressure waves was mixed with >50% occurring simultaneous. This high-frequency cyclic motor pattern co-existed with the well-known low-frequency cyclic motor pattern centered on 3-4 cpm. In the rectum, the low-frequency cyclic motor pattern dominated, propagating predominantly in retrograde direction. Proximal balloon distention, a meal and bisacodyl administration induced HAPWs followed by cyclic motor patterns.

CONCLUSIONS AND INFERENCES

Within cyclic motor patterns, retrograde propagating, low-frequency pressure waves dominate in the rectum, likely keeping the rectum empty; and mixed propagation, high-frequency pressure waves dominate in the colon, likely promoting absorption and storage, hence contributing to continence. Propagation and frequency characteristics are likely determined by network properties of the interstitial cells of Cajal.

Ambulatory assessment of colonic motility using the electromagnetic capsule tracking system: Effect of opioids

BACKGROUND

Opioid treatment often causes debilitating constipation. However, it is not well described how opioids affect colonic motility and whether opioid-induced constipation is due to either a decrease of powerful peristaltic contractions or "uncoordinated" peristalsis. The present study aims to investigate the effect of oxycodone on parameters of colonic motility and to determine whether motility is normalized by the opioid antagonist naloxegol.

METHODS

In two randomized, double-blind crossover trials, oxycodone or placebo was administered to 25 healthy males (Trial A), while another 24 healthy males were administered oxycodone with naloxegol or placebo (Trial B). Colonic motility was assessed by tracking the progression of an electromagnetic capsule throughout the large intestine. Segmental colonic transit times and capsule movements were calculated using displacement distance and velocity.

KEY RESULTS

In Trial A, colonic transit time increased during oxycodone treatment compared with placebo (39 vs 18 hours, P < .01). Displacement during long fast antegrade movements was shorter during oxycodone treatment than with placebo (10 vs 20 cm, P = .03). In Trial B, colonic transit time was faster during oxycodone + naloxegol than during oxycodone + placebo (40 vs 55 hours, P = .049), mainly caused by an increase of the percentwise fraction of distance covered by fast movements in the left colon (P = .001).

CONCLUSION & INFERENCES

Oxycodone treatment impaired colonic motility, manifested as increased transit time, specifically decreased long fast antegrade movements, and addition of naloxegol improved motility dynamics. In humans, the increased transit time during opioid treatment is caused by a decrease in long fast movements rather than uncoordinated peristalsis.

Management of functional constipation in children and adults

Functional constipation is common in children and adults worldwide. Functional constipation shows similarities in children and adults, but important differences also exist regarding epidemiology, symptomatology, pathophysiology, diagnostic workup and therapeutic management. In children, the approach focuses on the behavioural nature of the disorder and the initial therapeutic steps involve toilet training and laxatives. In adults, management focuses on excluding an underlying cause and differentiating between different subtypes of functional constipation - normal transit, slow transit or an evacuation disorder - which has important therapeutic consequences. Treatment of adult functional constipation involves lifestyle interventions, pelvic floor interventions (in the presence of a rectal evacuation disorder) and pharmacological therapy. When conventional treatments fail, children and adults are considered to have intractable functional constipation, a troublesome and distressing condition. Intractable constipation is managed with a stepwise approach and in rare cases requires surgical interventions such as antegrade continence enemas in children or colectomy procedures for adults. New drugs, including prokinetic and prosecretory agents, and surgical strategies, such as sacral nerve stimulation, have the potential to improve the management of children and adults with intractable functional constipation.

Chronic Constipation

Constipation is a common symptom that may be primary (idiopathic or functional) or associated with a number of disorders or medications. Although most constipation is self-managed by patients, 22% seek health care, mostly to primary care physicians (>50%) and gastroenterologists (14%), resulting in large expenditures for diagnostic testing and treatments. There is strong evidence that stimulant and osmotic laxatives, intestinal secretagogues, and peripherally restricted μ-opiate antagonists are effective and safe; the lattermost drugs are a major advance for managing opioid-induced constipation. Constipation that is refractory to available laxatives should be evaluated for defecatory disorders and slow-transit constipation using studies of anorectal function and colonic transit. Defecatory disorders are often responsive to biofeedback therapies, whereas slow-transit constipation may require surgical intervention in selected patients. Both efficacy and cost should guide the choice of treatment for functional constipation and opiate-induced constipation. Currently, no studies have compared inexpensive laxatives with newer drugs that work by other mechanisms.

Effects of Naloxegol on Gastrointestinal Transit and Colonic Fecal Volume in Healthy Participants Receiving Oxycodone

Background/Aims

Opioids cause gastrointestinal (GI) dysmotility, decrease gut secretion, and affect gut sphincters. Symptoms of opioid-induced bowel dysfunction may be alleviated by peripherally acting opioid antagonists like naloxegol, but detailed knowledge on GI effects of this drug is lacking. We hypothesized that naloxegol, compared to placebo, would reduce GI transit time and colonic fecal volume in opioid-treated healthy participants.

Methods

We conducted a randomized, double-blinded, single-center, 2-way cross-over study in 24 healthy males, randomized to a 6 day treatment period of oxycodone (15 mg twice a day) co-administered with either naloxegol (25 mg once a day) or matching placebo. Participants swallowed an electromagnetic capsule which determined GI transit times. Colonic fecal volume was quantified with magnetic resonance imaging both pre-treatment and post-treatment.

Results

Naloxegol reduced total GI transit time by 21% (56 hours vs 71 hours, P = 0.02) and colonic transit time by 23% (45 hours vs 59 hours, P < 0.01), compared to placebo. However, no difference in colonic fecal volume was found (818 mL vs 884 mL, P = 0.20).

Conclusions

Short-term administration of naloxegol in healthy participants reverses the retardation of total GI and colonic transit induced by oxycodone. This supports the use of naloxegol in the treatment of GI side effects to opioid treatment, and add knowledge to the current understanding of mechanisms behind peripherally-acting opioid antagonists.

Intraluminal prucalopride increases propulsive motor activities via luminal 5-HT4 receptors in the rabbit colon

BACKGROUND

Activating luminal 5-HT₄ receptors results in the release of 5-HT from enterochromaffin cells into the lamina propria to modulate colonic motility. Our aim was to evaluate characteristics of colonic motor patterns involved in the prokinetic effects of intraluminal prucalopride in the rabbit colon.

METHODS

Colonic motor patterns were studied ex vivo using simultaneous spatiotemporal diameter mapping and pressure sensing.

KEY RESULTS

Intraluminal prucalopride and intraluminal exogenous 5-HT strongly evoked or enhanced the colonic motor complex at all levels of excitation beginning with generation of clusters of fast propagating contractions (FPCs), then development of long-distance contractions (LDCs) within the clusters, and finally forceful LDCs as the highest level of excitation. Intraluminal prucalopride and intraluminal exogenous 5-HT stimulated propulsive motor activity in a dose-dependent and antagonist-sensitive manner by increasing the contraction amplitude, intraluminal pressure, frequency, velocity, and degree of propagation of the colonic motor complex.

CONCLUSIONS AND INFERENCES

Activating mucosal 5-HT₄ receptors via intraluminal prucalopride or 5-HT increases propulsive motor activity in a graded manner; that is, depending on starting conditions, amplitudes or frequencies of an activity may increase or a new pattern may be initiated. Our data support further studies into delivering 5-HT₄ receptor agonists via colon-targeted drug delivery systems and studies into the role of luminal 5-HT as an essential requirement for normal colon motor pattern generation.

Long-term outcome after segmental colonic resection for slow transit constipation

PURPOSE

Colectomy with ileorectal anastomosis (IRA) is the most common surgical procedure for slow transit constipation (STC). A hemicolectomy has been suggested as an alternative to IRA with good short-term results. However, long-term results are unknown. The aim of this study was to evaluate the long-term results after hemicolectomy as a treatment for STC.

METHODS

Fifty patients with STC were selected for right- or left-sided hemicolectomy after evaluation with colonic scintigraphy from 1993 to 2008. Living patients (n = 43) received a bowel function questionnaire and a questionnaire about patient-reported outcome.

RESULTS

After a median follow-up of 19.8 years, 13 patients had undergone rescue surgery (n = 12) or used irrigation (n = 1) and were classified as failures. In all, 30 were evaluable for functional outcome and questionnaire data for 19 patients (due to 11 non-responding) could be analysed. Two reported deterioration after several years and were also classified as failures. Median stool frequency remained increased from 1 per week at baseline to 5 per week at long-term follow-up (p = 0.001). Preoperatively, all patients used laxatives, whereas 12 managed without laxatives at long-term follow-up (p = 0.002). There was some reduction in other constipation symptoms but not statically significant. In the patients' global assessment, 10 stated a very good result, seven a good result and two a poor result.

CONCLUSIONS

Hemicolectomy for STC increases stool frequency and reduces laxative use. Long-term success rate could range between 17/50 (34%) and 35/50 (70%) depending on outcome among non-responders.

Chronic idiopathic constipation in adults: epidemiology, pathophysiology, diagnosis and clinical management

Chronic idiopathic constipation (CIC) is one of the most common gastrointestinal disorders, with a global prevalence of 14%. It is commoner in women and its prevalence increases with age. There are three subtypes of CIC: dyssynergic defaecation, slow transit constipation and normal transit constipation, which is the most common subtype. Clinical assessment of the patient with constipation requires careful history taking, in order to identify any red flag symptoms that would necessitate further investigation with colonoscopy to exclude colorectal malignancy. Screening for hypercalcaemia, hypothyroidism and coeliac disease with appropriate blood tests should be considered. A digital rectal examination should be performed to assess for evidence of dyssynergic defaecation. If this is suspected, further investigation with high resolution anorectal manometry should be undertaken. Anorectal biofeedback can be offered to patients with dyssynergic defaecation as a means of correcting the associated impairment of pelvic floor, abdominal wall and rectal functioning. Lifestyle modifications, such as increasing dietary fibre, are the first step in managing other causes of CIC. If patients do not respond to these simple changes, then treatment with osmotic and stimulant laxatives should be trialled. Patients not responding to traditional laxatives should be offered treatment with prosecretory agents such as lubiprostone, linaclotide and plecanatide, or the 5-HT4 receptor agonist prucalopride, where available. If there is no response to pharmacological treatment, surgical intervention can be considered, but it is only suitable for a carefully selected subset of patients with proven slow transit constipation.

Spatio-temporal motility MRI analysis of the stomach and colon

BACKGROUND

MRI is increasingly used to objectively assess gastrointestinal motility. However, motility metrics often do not offer insights into the nature of contractile action. This study introduces a systematic method of making spatio-temporal measurements of contractions, based on changes in bowel lumen diameter.

METHODS

Two heterogeneous cohorts of subjects were selected displaying gastric (n = 15) and colonic motility (n = 20) on which to test the spatio-temporal motility MRI (STMM) technique. STMM involved delineating the bowel lumen along with inner and outer bowel wall along a section of the gastrointestinal tract. A series of diameter measurements were made automatically across the central axis of the lumen. Measurements were automatically propagated through the time series using a previously validated algorithm. Contractions were quantitatively summarized with two methods measuring (a) normalized contraction plot (NCP) and (b) combined velocity distance (CVD) both of which can be visualized as spatio-temporal motility maps. Both metrics were correlated against subjective visual scoring systems.

KEY RESULTS

Good correlation was seen between reader scores and both motility metrics (NCP, R = 0.85, P < 0.001, CVD, R = 0.93, R < 0.001) in the gastric data. Good correlation was also seen between the reader scores and the two metrics in the colonic data (NCP, R = 0.82, P < 0.001, CVD, R = 0.78, R < 0.001).

CONCLUSIONS AND INFERENCES

Spatio-temporal motility MRI analysis of the stomach and colon correlates well with reader scores in a range of datasets and provides both a quantitative and qualitative means of assessing contractile activity in the gastrointestinal tract.

Ambulatory assessment of colonic motility using the electromagnetic capsule tracking system

BACKGROUND

The Motilis 3D-Transit system tracks electromagnetic capsules as they traverse the gastrointestinal tract. The method is minimally invasive and ambulatory. Analysis has previously been limited to regional gut transit times, but new methods may allow detailed analysis of colonic motility.

METHODS

Parameters of colonic motility were analyzed from 34 3D-Transit recordings performed in healthy volunteers (median age 28 years; 8 F). Characteristic propulsive velocities and lengths of movement were determined to quantify common movement patterns. Data from seven patients with severe chronic diarrhea were included for comparison.

KEY RESULTS

Lack of capsule motion accounted for 82% (75%-87%) of total colonic transit time. Propulsive velocities were distributed with peaks at 0.5 cm/min (antegrade or retrograde) and 50 cm/min (antegrade). Based on velocity and length of propagation, five motor patterns were identified; (a) long fast antegrade, (b) fast antegrade, (c) slow antegrade, (d) slow retrograde, and (e) fast retrograde movements. Long fast antegrade movements were median 21 cm (10-96 cm). Capsule progression was faster during daytime than at night (5.9 cm/h vs 0.8 cm/h; P < 0.01). Colonic transit was faster in patients with chronic diarrhea than in healthy volunteers (5.4 h vs 18.2 h; P = 0.04), with higher capsule velocity (20.4 cm/h vs 4.4 cm/h; P < 0.01).

CONCLUSIONS AND INFERENCES

The 3D-Transit system now allows detailed description of colonic motility and our results are supported by those previously suggested by manometry. It holds promise for future assessment of movement patterns to characterize different diseases and effects of treatment.

More movement with evaluating colonic transit in humans

BACKGROUND

Colonic functions (ie, absorption of fluids and electrolytes, digestion of selected nutrients, harbor for microbes, and elimination of excreta) necessitate complex patterns of storage and transit. Indeed, colonic transit accounts for a major part of the mouth-to-anus transit time. Colonic transit assessments are useful for understanding the pathophysiology of disease, the pharmacodynamic effects of new medications and to diagnose slow transit constipation. Currently, radiopaque markers, scintigraphy, and a colonic pH-pressure capsule are used to measure overall colonic transit. Radioopaque markers, scintigraphy, and the electromagnetic capsule, which is a newer technique, also evaluate regional colonic transit. The pH-pressure capsule also measures colonic pressures. Magnetic resonance imaging and a radio-frequency identification-based device are evolving methods for assessing colonic transit.

PURPOSE

This mini-review, which accompanies a study evaluating the assessment of colon transit with the electromagnetic capsule, evaluates and compares existing and evolving methods for evaluating colonic transit in humans (Neurogastroenterol Motil. 2018; in press). In addition to overall and regional colonic transit, the electromagnetic capsule evaluates colonic motor patterns without radiation exposure. These patterns are summarized by analyzing the characteristics (ie, distance and velocity) of discrete antegrade and retrograde capsule movements as they travel in the colon. However, the electromagnetic capsule does not measure pressure or colonic wall movement (ie, contractions). The motor patterns identified by this capsule should be compared with motor patterns identified with manometry. The next challenge is to harness different techniques to evaluate the relationships between colonic pressures and transit or, even better, the trifecta of colonic contractions, pressure events, and transit.

A new understanding of the physiology and pathophysiology of colonic motility?

BACKGROUND

In recent years, high-resolution manometry has been used in an attempt to gain a greater insight into the physiology/pathophysiology of colonic contractile activity in healthy adults and patients with colonic motility disorders. New colonic motor patterns have been identified and characterized, however, the clinical significance of these findings remains undetermined.

PURPOSE

This review will assess the current literature on colonic high-resolution manometry and determine if this procedure has advanced our understanding of colonic motility. The limitations, future directions, and the potential of this technique to assess the effects of treatment upon colonic motor patterns will also be discussed.

The evolution of magnetic resonance enterography in the assessment of motility disorders in children

Gastrointestinal symptoms including constipation, diarrhoea, pain and bloating represent some of the most common clinical problems for patients. These symptoms can often be managed with cheap, widely available medication or will spontaneously resolve. However, for many patients, chronic GI symptoms persist and frequently come to dominate their lives. At one end of the spectrum there is Inflammatory Bowel Disease (IBD) with a clearly defined but expensive treatment pathway. Contrasting with this is Irritable Bowel Syndrome (IBS), likely a collection of pathologies, has a poorly standardised pathway with unsatisfactory clinical outcomes. Managing GI symptoms in adult populations is a challenge. The clinical burden of gastrointestinal disease is also prevalent in paediatric populations and perhaps even harder to treat. In this review we explore some of the recent advances in magnetic resonance imaging (MRI) to study the gastrointestinal tract. Complex in both its anatomical structure and its physiology we are likely missing key physiological markers of disease through relying on symptomatic descriptors of gut function. Using MRI we might be able to characterise previously opaque processes, such as non-propulsive contractility, that could lead to changes in how we understand even common symptoms like constipation. This review explores recent advances in the field in adult populations and examines how this safe, objective and increasingly available modality might be applied to paediatric populations.

Motility of the left colon in children and adolescents with functional constpation; a retrospective comparison between solid-state and water-perfused colonic manometry

BACKGROUND

Using water-perfused (WP) high-resolution manometry, we recently demonstrated that children with functional constipation (FC) lacked the postprandial increase in distal colonic cyclic motor patterns that was observed in healthy adults. Our aim was to determine if similar results could be detected using a solid-state (SS) manometry catheter.

METHODS

We performed a retrospective analysis of 19 children with FC (median age 11.1 years, 58% male) who underwent colonic manometry with a SS catheter (36 sensors, 3 cm apart). Data were compared with previously published data using a WP catheter (36 sensors, 1.5 cm apart) recorded from 18 children with FC (median age 15 years; 28% male).

KEY RESULTS

The cyclic motor patterns recorded by the SS catheter did not differ from those previously recorded by the WP catheter. There was no detected increase in this activity in response to the meal in either group. Long-single motor patterns were recorded in most patients (n = 16, 84%) with the SS catheter. The number of these events did not differ from the WP recordings. In the SS data, HAPCs were observed in 4 children prior to the meal, in 5 after the meal. This did not differ significantly from the WP data.

CONCLUSIONS & INFERENCES

These data recorded by SS manometry did not differ from WP manometry data. Regardless of the catheter used, both studies revealed an abnormal colonic response to a meal, indicating a pathology which is not related to the catheter used to record these data.

Gastrointestinal Transit Time in Parkinson's Disease Using a Magnetic Tracking System

BACKGROUND

Symptoms from the gastrointestinal tract are highly prevalent in Parkinson's disease (PD), but knowledge of the underlying pathology is incomplete and valid objective markers on regional gastrointestinal function are limited.

OBJECTIVE

The aims were to evaluate gastrointestinal transit time and motility in PD patients and controls.

METHODS

Twenty-two PD patients and 15 controls were included. Gastric-, small intestinal-, and caecum-ascending colonic transit times as well as colonic motility, defined as mass- and fast movements, were performed using the ambulatory 3D-Transit system. Gastrointestinal transit time with radio opaque markers, gastric emptying scintigraphy, and subjective non-motor symptoms were also evaluated.

RESULTS

Using the 3D-Transit system, the patient group displayed significantly longer small intestinal- and caecum-ascending transit times (p = 0.030 and p = 0.0063). No between-group difference was seen in gastric transit time (p = 0.91). Time to first mass- and fast colonic movement were significantly increased in PD (p = 0.023 and p = 0.006). Radio opaque marker gastrointestinal transit time was significantly increased in the patient group (p < 0.0001), whereas no difference was seen in scintigraphic gastric emptying time (p = 0.68). Prevalence of constipation symptoms on the NMSQuest was 41% in PD and 7% in controls.

CONCLUSIONS

Significantly increased small intestinal- and caecum-ascending 3D-Transit times were detected in PD patients. Also, time to first propagating colonic movement was increased. Radio opaque marker gastrointestinal transit time was significantly delayed, but no difference was seen in gastric transit time and gastric emptying time. The present findings highlight widespread intestinal involvement in PD increasing throughout the gastrointestinal tract.

Colonic motor response to wakening is blunted in slow transit constipation as detected by wireless motility capsule

Background

Chronic constipation may be categorized as normal transit (NTC), slow transit (STC), or outlet obstruction. Colonic wake response is a relative increase in colonic motility upon awakening. Colonic manometry studies have demonstrated attenuated wake response in STC. We sought to evaluate wake response among healthy (H), NTC, and STC patients using wireless motility capsule (WMC).

Methods

A retrospective study of WMC data from a multicenter clinical trial and a tertiary gastroenterology clinic was performed. WMC motility parameters of contraction frequency (Ct) and area under the contraction curve (AUC) were analyzed in 20-min windows 1-h before and after awakening. T-tests compared parameters between H, NTC, and STC. Linear regression analysis was performed to determine if outlet obstruction confounded data. A receiver operating characteristic curve demonstrated optimal Ct cut-offs to define blunted wake response.

Results

A total of 62 H, 53 NTC and 75 STC subjects were analyzed. At 20, 40, and 60 min after awakening, STC subjects had significantly lower mean Ct when compared to H (p < 0.001) and NTC (p < 0.01). Linear regression demonstrated that outlet obstruction was not associated with a decreased wake response (β = 3.94, (CI −3.12–1.00), P = 0.27). Defined at the Ct threshold of 64 at 20-min post-wake, blunted wake response sensitivity was 84% and specificity was 32% for chronic constipation.

Conclusion

Findings of an impaired wake response in subjects with STC and not NTC adds further evidence to neuronal dysfunction as an etiology of STC, and identifies a possible temporal target for pharmacologic intervention.

Hyperactive cyclic motor activity in the distal colon after colonic surgery as defined by high-resolution colonic manometry

BACKGROUND

Recovery after colonic surgery is invariably delayed by disturbed gut motility. It is commonly assumed that colonic motility becomes quiescent after surgery, but this hypothesis has not been evaluated rigorously. This study quantified colonic motility through the early postoperative period using high-resolution colonic manometry.

METHODS

Fibre-optic colonic manometry was performed continuously before, during and after surgery in the left colon and rectum of patients undergoing right hemicolectomy, and in healthy controls. Motor events were characterized by pattern, frequency, direction, velocity, amplitude and distance propagated.

RESULTS

Eight patients undergoing hemicolectomy and nine healthy controls were included in the study. Colonic motility became markedly hyperactive in all operated patients, consistently dominated by cyclic motor patterns. Onset of cyclic motor patterns began to a minor extent before operation, occurring with increasing intensity nearer the time of surgery; the mean(s.d.) active duration was 12(7) per cent over 3 h before operation and 43(17) per cent within 1 h before surgery (P = 0.024); in fasted controls it was 2(4) per cent (P < 0·001). After surgery, cyclic motor patterns increased markedly in extent and intensity, becoming nearly continuous (active duration 94(13) per cent; P < 0·001), with peak frequency 2-4 cycles per min in the sigmoid colon. This postoperative cyclic pattern was substantially more prominent than in non-operative controls, including in the fed state (active duration 27(20) per cent; P < 0·001), and also showed higher antegrade velocity (P < 0·001).

CONCLUSION

Distal gut motility becomes markedly hyperactive with colonic surgery, dominated by cyclic motor patterns. This hyperactivity likely represents a novel pathophysiological aspect of the surgical stress response. Hyperactive motility may contribute to gut dysfunction after surgery, potentially offering a new therapeutic target to enhance recovery.

The "rectosigmoid brake": Review of an emerging neuromodulation target for colorectal functional disorders

The regulation of gastrointestinal motility encompasses several overlapping mechanisms including highly regulated and coordinated neurohormonal circuits. Various feedback mechanisms or "brakes" have been proposed. While duodenal, jejunal, and ileal brakes are well described, a putative distal colonic brake is less well defined. Despite the high prevalence of colonic motility disorders, there is little knowledge of colonic motility owing to difficulties with organ access and technical difficulties in recording detailed motor patterns along its entire length. The motility of the colon is not under voluntary control. A wide range of motor patterns is seen, with long intervals of intestinal quiescence between them. In addition, the use of traditional manometric catheters to record contractile activity of the colon has been limited by the low number of widely spaced sensors, which has resulted in the misinterpretation of colonic motor patterns. The recent advent of high-resolution (HR) manometry is revolutionising the understanding of gastrointestinal motor patterns. It has now been observed that the most common motor patterns in the colon are repetitive two to six cycles per minute (cpm) propagating events in the distal colon. These motor patterns are prominent soon after a meal, originate most frequently in the rectosigmoid region, and travel in the retrograde direction. The distal prominence and the origin of these motor patterns raise the possibility of them serving as a braking mechanism, or the "rectosigmoid brake," to limit rectal filling. This review aims to describe what is known about the "rectosigmoid brake," including its physiological and clinical significance and potential therapeutic applications.

Prokinetics in the Management of Functional Gastrointestinal Disorders

PURPOSE OF REVIEW

The goal of this review is to review the current status of prokinetics and to place it in historical context. Impaired motility and thus propulsion have long been thought to play important roles in the pathogenesis of a number of gastrointestinal disorders including gastroesophageal reflux disease (GERD), gastroparesis, chronic idiopathic pseudo-obstruction, and constipation. Historically, disordered motility was also thought to contribute to a number of functional gastrointestinal disorders such as functional dyspepsia (FD) and irritable bowel syndrome (IBS).

RECENT FINDINGS

As we learn more of the pathophysiology of FD, IBS, GERD, constipation, and gastroparesis, the limitations of a therapeutic strategy based on the stimulation of motility (i.e., the use of a prokinetic) have become apparent and the disappointments of the past explained. The development of prokinetic drugs has also been hampered by the non-selective nature of many of the agents studied to date which resulted in some unexpected side effects. There is still an unmet need for an effective and safe prokinetic, but drug development in this area must be mindful of the challenges of the area and the need for selectivity for a given target receptor.

Assessment of colorectal length using the electromagnetic capsule tracking system: a comparative validation study in healthy subjects

AIM

We aimed to determine colorectal length with the 3D-Transit system by describing a 'centreline' of capsule movement and comparing it with known anatomy, as determined by magnetic resonance imaging (MRI). Further, we aimed to test the day-to-day variation of colorectal length assessed with the system.

METHOD

The 3D-Transit system consists of electromagnetic capsules that can be tracked as they traverse the gastrointestinal tract. Twenty-five healthy subjects were examined with both 3D-Transit and MRI. Another 21 healthy subjects were examined with 3D-Transit on two consecutive days.

RESULTS

Computation of colorectal length from capsule passage was possible for 60 of the 67 3D-Transit recordings. The length of the colorectum measured with MRI and 3D-Transit was 95 (75-153) cm and 99 (77-147) cm, respectively (P = 0.15). The coefficient of variation (CV) between MRI and 3D-Transit was 7.8%. Apart from the caecum/ascending colon being 26% (P = 0.002) shorter on MRI, there were no other differences in total or segmental colorectal lengths between methods (all P > 0.05). The length of the colorectum measured with 3D-Transit on two consecutive days was 102 (73-119) cm and 103 (75-123) cm (P = 0.67). The CV between days was 7.3%.

CONCLUSION

The 3D-Transit system allows accurate and reliable determination of colorectal length compared with MRI-derived colorectal length and between days. Antegrade or retrograde capsule movement relative to this centreline, as well as the length and speed of movements, may be determined by future studies to allow better classification and treatment in patients with dysmotility.