Novel diagnostics and therapy of colonic motor disorders

Analysis of Intestinal Movements with Spatiotemporal Maps: Beyond Anatomy and Physiology

Over 150 years ago, methods for quantitative analysis of gastrointestinal motor patterns first appeared. Graphic representations of physiological variables were recorded with the kymograph after the mid-1800s. Changes in force or length of intestinal muscles could be quantified, however most recordings were limited to a single point along the digestive tract.In parallel, photography and cinematography with X-Rays visualised changes in intestinal shape, but were hard to quantify. More recently, the ability to record physiological events at many sites along the gut in combination with computer processing allowed construction of spatiotemporal maps. These included diameter maps (DMaps), constructed from video recordings of intestinal movements and pressure maps (PMaps), constructed using data from high-resolution manometry catheters. Combining different kinds of spatiotemporal maps revealed additional details about gut wall status, including compliance, which relates forces to changes in length. Plotting compliance values along the intestine enabled combined DPMaps to be constructed, which can distinguish active contractions and relaxations from passive changes. From combinations of spatiotemporal maps, it is possible to deduce the role of enteric circuits and pacemaker cells in the generation of complex motor patterns. Development and application of spatiotemporal methods to normal and abnormal motor patterns in animals and humans is ongoing, with further technical improvements arising from their combination with impedance manometry, magnetic resonance imaging, electrophysiology, and ultrasonography.

Simultaneous assessment of colon motility in children with functional constipation by cine-MRI and colonic manometry: a feasibility study

BACKGROUND

Colonic manometry is the current reference standard for assessing colonic neuromuscular function in children with intractable functional constipation (FC). Recently, cine magnetic resonance imaging (cine-MRI) has been proposed as a non-invasive alternative. We compared colonic motility patterns on cine-MRI with those obtained by manometry in children, by stimulating high-amplitude propagating contractions (HAPCs) with bisacodyl under manometric control while simultaneously acquiring cine-MRI.

METHODS

After Institutional Review Board approval, adolescents with FC scheduled to undergo colonic manometry were included. A water-perfused 8-lumen catheter was used for colonic manometry recordings. After an intraluminal bisacodyl infusion, cine-MRI sequences of the descending colon were acquired for about 30 min simultaneously with colonic manometry. Manometry recordings were analysed for HAPCs. MRI images were processed with spatiotemporal motility MRI techniques. The anonymised motility results of both techniques were visually compared for the identification of HAPCs in the descending colon.

RESULTS

Data regarding six patients (three males) were analysed (median age 14 years, range 12-17). After bisacodyl infusion, three patients showed a total of eleven HAPCs with colonic manometry. Corresponding cine-MRI recorded high colonic activity during two of these HAPCs, minimal activity during seven HAPCs, while two HAPCs were not recorded. In two of three patients with absent HAPCs on manometry, colonic activity was recorded with cine-MRI.

CONCLUSIONS

Simultaneous acquisition of colonic cine-MRI and manometry in children with FC is feasible. Their motility results did not completely overlap in the identification of HAPCs. Research is needed to unravel the role of cine-MRI in this setting.

Regional gastrointestinal contractility parameters using the wireless motility capsule: inter-observer reproducibility and influence of age, gender and study country

BACKGROUND

The wireless motility capsule concurrently measures temperature, pH and pressure as it traverses the gastrointestinal tract.

AIMS

To describe normative values for motility/contractility parameters across age, gender and testing centres.

METHODS

Healthy participants underwent a standardised wireless motility capsule assessment following an overnight fast and consumption of a meal of known nutritional content. Traces were divided into regions of interest and analysed using 2 software packages (MotiliGI and GIMS Data Viewer). Inter-observer agreement was independently assessed by 2 investigators.

RESULTS

Normative data for motility/contractility parameters (maximum amplitude, mean peak amplitude, contraction frequency and motility index) are presented for 107 individuals (62 male, median age 40 years, range 18-78). MotiliGI-Gastric, small bowel and colonic maximal contraction amplitude correlated with age (r = .24, P = .01; r = .22, P = .02; and r = .2, P = .04 respectively). Small bowel motility index was higher in females than males (150.4 ± 12 vs 122 ± 7.6, P = .04). Inter-observer agreement was excellent for transit times, pH and contractility/motility parameters. GIMS Data viewer-Gastric, small bowel and colonic log_e motility index correlated with the respective area under the contraction curve, total contractions, sum of amplitudes and contraction frequency (all r>.35, P < .0003) but not with transit times.

CONCLUSIONS

Our analysis provides normative data for motility/contractility parameters. Log motility index summarises a number of measures. In future, the measurement of contractile activity with the wireless motility capsule may potentially aid in the diagnosis of disease states such as visceral myopathic disorders.

Neuromodulation via Interferential Electrical Stimulation as a Novel Therapy in Gastrointestinal Motility Disorders

The concept of therapeutic percutaneous neuromodulation has, until recently, been limited by the ability to penetrate deeply enough to stimulate internal organs. By utilizing 2 medium frequency, slightly out of phase electrical currents passing diagonally through the abdomen, a third, low frequency current is created at the point of bisection. This interferential current appears to stimulate nerve fibers in the target organs and may have a therapeutic action. The aim of the study is to review the use of transcutaneous interferential electrical stimulation with a focus on its application in gastroenterology, particularly in motility disorders. Studies involving use of interferential current therapy were searched from Medline, PubMed, and Scopus databases, and articles pertaining to history, its application and all those treating abdominal and gastrointestinal disorders were retrieved. Seventeen studies were identified, 13 involved children only. Eleven of these were randomised controlled trials (3 in adults). Four trials were from the one center, where each paper reported on different outcomes such as soiling, defecation frequency, quality of life, and colon transit studies from the one pool of children. All studies found statistically significant improvement in symptom reduction. However, weaknesses in study design were apparent in some. In particular, finding an adequate placebo to interferential current therapy has been difficult. Interferential current therapy shows potential as a novel, non-pharmacological and economical means of treating gastrointestinal dysfunction such as constipation. More studies are needed particularly in the adult population. However, the design of a suitable placebo is challenging.

From clinical uncertainties to precision medicine: the emerging role of the gut barrier and microbiome in small bowel functional diseases

Over the last decade, remarkable progress has been made in the understanding of disease pathophysiology. Many new theories expound on the importance of emerging factors such as microbiome influences, genomics/omics, stem cells, innate intestinal immunity or mucosal barrier complexities. This has introduced a further dimension of uncertainty into clinical decision-making, but equally, may shed some light on less well-understood and difficult to manage conditions. Areas covered: Comprehensive review of the literature on gut barrier and microbiome relevant to small bowel pathology. A PubMed/Medline search from 1990 to April 2017 was undertaken and papers from this range were included. Expert commentary: The scenario of clinical uncertainty is well-illustrated by functional gastrointestinal disorders (FGIDs). The movement towards achieving a better understanding of FGIDs is expressed in the Rome IV guidelines. Novel diagnostic and therapeutic protocols focused on the GB and SB microbiome can facilitate diagnosis, management and improve our understanding of the underlying pathological mechanisms in FGIDs.

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.

Postoperative ileus: mechanisms and future directions for research

Postoperative ileus (POI) is an abnormal pattern of gastrointestinal motility characterized by nausea, vomiting, abdominal distension and/or delayed passage of flatus or stool, which may occur following surgery. Postoperative ileus slows recovery, increases the risk of developing postoperative complications and confers a significant financial load on healthcare institutions. The aim of the present review is to provide a succinct overview of the clinical features and pathophysiological mechanisms of POI, with final comment on selected directions for future research.Terminology used when describing POI is inconsistent, with little differentiation made between the obligatory period of gut dysfunction seen after surgery ('normal POI') and the more clinically and pathologically significant entity of a 'prolonged POI'. Both normal and prolonged POI represent a fundamentally similar pathophysiological phenomenon. The aetiology of POI is postulated to be multifactorial, with principal mediators being inflammatory cell activation, autonomic dysfunction (both primarily and as part of the surgical stress response), agonism at gut opioid receptors, modulation of gastrointestinal hormone activity and electrolyte derangements. A final common pathway for these effectors is impaired contractility and motility and gut wall oedema. There are many potential directions for future research. In particular, there remains scope to accurately characterize the gastrointestinal dysfunction that underscores an ileus, development of an accurate risk stratification tool will facilitate early implementation of preventive measures and clinical appraisal of novel therapeutic strategies that target individual pathways in the pathogenesis of ileus warrant further investigation.

High resolution colonic manometry--what have we learnt?--A review of the literature 2012

Despite its size and physiological importance, the human colon is one of the least understood organs of the body. Many disorders arise from suspected abnormalities in colonic contractions, yet, due largely to technical constraints, investigation of human colonic motor function still remains relatively primitive. Most measures of colonic motility focus upon the transit speed (radiology, scintigraphy and, more recently, "smart pills"); however, only colonic manometry can measure pressure/force from multiple regions within the colon in real time (Dinning and Scott (Curr Opin Pharmacol 11:624-629, 2011)). Based upon data from colonic manometry studies, a number of different colonic motor patterns have been distinguished: (1) antegrade high amplitude propagating sequences (contractions), (2) low amplitude propagating sequences, (3) non-propagating contractions, and (4) and rarely episodes of retrograde (oral) propagating pressure waves (Dining and Di Lorenzo (Best Pract Res Clin Gastrolenterol 25(1): 89-101, 2011)). Abnormalities in the characteristics of these motor patterns should help to characterize dysmotility in a patient populations, and in both adults and children colonic motor abnormalities have been identified with manometry studies (Rao et al. Am J Gastroenterol 99(12):2405-2416, (2004), Di Lorenzo et al. Gut. 34(1): 803-807, (1993)). Yet, despite more than two decades of such studies, the clinical utility of colonic manometry remains marginal with no specific manometric biomarkers of colonic dysfunction being established ([Camilleri et al. Neurogastroenterol Motil. 20(12): 1269-1282, 2008). This has been highlighted recently in a colonic manometry study by Singh et al. (2013), in which 41 % of 80 patients, with confirmed slow transit constipation, were reported to have normal motility. While this may suggest that no motor abnormalities exist in a proportion of such patients, the finding may also reflect technical constraints in our ability to detail colonic motility patterns.

Exogenous interleukin-6 facilitated the contraction of the colon in a depression rat model

BACKGROUND

Gut dysmotility is closely associated with proinflammatory cytokines both in irritable bowel syndrome and inflammatory bowel disease. There is a dose-response relationship between depression and these inflammatory cytokines.

AIMS

In the present study, we aimed to investigate the effect of Interleukin-6 (IL-6) on colon motility in a rat model of depression induced by chronic unpredictable mild stress (CUMS).

METHODS

The contraction of the circular muscle strips of proximal colon was monitored by a polygraph. IL-6 and IL-6 receptor (IL-6R) mRNA was assayed by real-time quantitative PCR. Immunohistochemistry staining was used to locate the IL-6 and IL-6R in the rat colon.

RESULTS

IL-6 and IL-6R were expressed in the mucosal layer, smooth muscle cells, and myenteric plexus of the colon. Exogenous IL-6 (20 ng/ml) increased the contraction of the circular muscle strip. Pretreatment of tetrodotoxin (blocker of voltage-dependent Na(+) channel on nerve fiber) blocks the excitatory effect of IL-6 on the contraction of the colon in non-stressed rats, but partially inhibited IL-6-induced excitatory effect on the muscle strips in CUMS-treated rats.

CONCLUSIONS

These results suggest that IL-6-induced the contraction of the colonic strip by acting on the gut's nervous system and acting directly on the smooth muscle in rats with depression.

Drug development for the irritable bowel syndrome: current challenges and future perspectives

Medications are frequently used for the treatment of patients with the irritable bowel syndrome (IBS), although their actual benefit is often debated. In fact, the recent progress in our understanding of the pathophysiology of IBS, accompanied by a large number of preclinical and clinical studies of new drugs, has not been matched by a significant improvement of the armamentarium of medications available to treat IBS. The aim of this review is to outline the current challenges in drug development for IBS, taking advantage of what we have learnt through the Rome process (Rome I, Rome II, and Rome III). The key questions that will be addressed are: (a) do we still believe in the "magic bullet," i.e., a very selective drug displaying a single receptor mechanism capable of controlling IBS symptoms? (b) IBS is a "functional disorder" where complex neuroimmune and brain-gut interactions occur and minimal inflammation is often documented: do we need to target gut motility, visceral sensitivity, or minimal inflammation? (c) are there validated biomarkers (accepted by regulatory agencies) for studies of sensation and motility with experimental medications in humans? (d) do animal models have predictive and translational value? (e) in the era of personalized medicine, does pharmacogenomics applied to these medications already play a role? Finally, this review will briefly outline medications currently used or in development for IBS. It is anticipated that a more focused interaction between basic science investigators, pharmacologists, and clinicians will lead to better treatment of IBS.