Characterization of a hyperactive segment at the rectosigmoid junction

The Sphincter of O'Beirne - Part 1: Study of 18 Normal Subjects

BACKGROUND

Gastroenterologists have ignored or emphasized the importance of the rectosigmoid junction in continence or constipation on and off for 200 years. Here, we revisit its significance using high-resolution colonic manometry.

METHODS

Manometry, using an 84-channel water-perfused catheter, was performed in 18 healthy volunteers.

RESULTS

The rectosigmoid junction registers as an intermittent pressure band of 26.2 ± 7.2 mmHg, or intermittent phasic transient pressure increases at a dominant frequency of 3 cpm and an amplitude of 28.6 ± 8.6 mmHg; or a combination of tone and transient pressures, at a single sensor, 10-17 cm above the anal verge. Features are its relaxation or contraction in concert with relaxation or contraction of the anal sphincters when a motor pattern such as a high-amplitude propagating pressure wave or a simultaneous pressure wave comes down, indicating that such pressure increases or decreases at the rectosigmoid junction are part of neurally driven programs. We show that the junction is a site where motor patterns end, or where they start; e.g. retrogradely propagating cyclic motor patterns emerge from the junction.

CONCLUSIONS

The rectosigmoid junction is a functional sphincter that should be referred to as the sphincter of O'Beirne; it is part of the "braking mechanism," contributing to continence by keeping content away from the rectum. In an accompanying case report, we show that its excessive presence in a patient with severe constipation can be a primary pathophysiology.

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.

Characterization of haustral activity in the human colon

Contraction patterns of the human colon are rarely discussed from the perspective of its haustra. Colonic motility was analyzed in 21 healthy subjects using 84-sensor manometry catheters with 1-cm sensor spacing. Capsule endoscopy and manometry showed evidence of narrow rhythmic circular muscle contractions. X-ray images of haustra and sensor locations allowed us to identify manometry motor activity as intrahaustral activity. Two common motor patterns were observed that we infer to be associated with individual haustra: rhythmic pressure activity confined to a single sensor, and activity confined to a section of the colon of 3-6 cm length. Intrahaustral activity was observed by 3-4 sensors. Approximately 50% of the haustra were intermittently active for ∼30% of the time; 2,402 periods of haustral activity were analyzed. Intrahaustral activity showed rhythmic pressure waves, propagating in mixed direction, 5-30 mmHg in amplitude at a frequency of ∼3 cpm (range 2-6) or ∼12 cpm (range 7-15), or exhibiting a checkerboard segmentation pattern. Boundaries of the haustra showed rhythmic pressure activity with or without elevated baseline pressure. Active haustra often showed no boundary activity probably allowing transit to neighboring haustra. Haustral boundaries were seen at the same sensor for the 6- to 8-h study duration, indicating that they did not propagate, thereby likely contributing to continence. The present study elucidates the motility characteristics of haustral boundaries and the nature of intrahaustral motor patterns and paves the way for investigating their possible role in pathophysiology of defecation disorders.NEW & NOTEWORTHY Here, we present the first full characterization and quantification of motor patterns that we infer to be confined to single haustra, both intrahaustral activity and haustral boundary activity, in the human colon using high-resolution manometry. Haustral activity is intermittent but consistently present in about half of the haustra. Intrahaustral activity presents as a cyclic motor pattern of mixed propagation direction dominated by simultaneous pressure waves that can resolve into checkerboard segmentation, allowing for mixing, absorption, and stool formation.

Central nervous system plus autonomic nervous system disorders responsible for gastrointestinal and pancreatobiliary diseases

Clinical digestive disorders depend on the non-adequate coupling of functioning of the gastrointestinal tract with that of its affluent systems, namely, the pancreatic exocrine and the hepato-biliary secretions. The secretion of gastrointestinal hormones is monitored by the peripheral autonomic nervous system. However, the latter is regulated by the central nervous system (CNS) circuitry localized at the medullary pontine segment of the CNS. In turn, both parasympathetic and adrenergic medullary circuitries are regulated by the pontine A5 noradrenergic (NA) and the dorsal raphe serotonergic nuclei, respectively. DR-5HT is positively correlated with the C1-Ad medullary nuclei (responsible for adrenal gland secretion), whereas the MR-5HT nucleus is positively correlated with the A5-NA pontomedullary nucleus. The latter is responsible for neural sympathetic activity (sympathetic nerves). Both types of sympathetic activities maintain an alternation with the peripheral parasympathetic branch, which is positively correlated with the enterochromaffin cells that secrete serotonin. Serotonin displays hormonal antagonism to the circulating catecholamines.

Constipation: evaluation and treatment of colonic and anorectal motility disorders

This article focuses on the colonic and anorectal motility disturbances that are associated with chronic constipation and their management. Functional chronic constipation consists of three overlapping subtypes: slow transit constipation, dyssynergic defecation, and irritable bowel syndrome with constipation. The Rome criteria may serve as a useful guide for making a clinical diagnosis of functional constipation. Today, an evidence-based approach can be used to treat patients with chronic constipation. The availability of specific drugs for the treatment of chronic constipation, such as tegaserod and lubiprostone, has enhanced the therapeutic armamentarium for managing these patients. Randomized controlled trials have also established the efficacy of biofeedback therapy in the treatment of dyssynergic defecation.

Constipation: evaluation and treatment of colonic and anorectal motility disorders

This article focuses on the colonic and anorectal motility disturbances that are associated with chronic constipation and their management. Functional chronic constipation consists of three overlapping subtypes: slow transit constipation, dyssynergic defecation, and irritable bowel syndrome with constipation. The Rome criteria may serve as a useful guide for making a clinical diagnosis of functional constipation. Today, an evidence-based approach can be used to treat patients with chronic constipation. The availability of specific drugs for the treatment of chronic constipation, such as tegaserod and lubiprostone, has enhanced the therapeutic armamentarium for managing these patients. Randomized controlled trials have also established the efficacy of biofeedback therapy in the treatment of dyssynergic defecation.

Mortality due to constipation and short-segment Hirschsprung's disease

We report a case of mortality secondary to constipation. A 12-year-old child with a history of constipation from the age of 9 years presented in moribund condition with intestinal obstruction secondary to idiopathic constipation. He underwent laparotomy and died within 24 h of operation. At postmortem there was no evidence of abnormalities of the enteric nervous system. A 2nd case of early neonatal death from Hirschsprung's disease is presented to demonstrate that short-segment aganglionosis can be detected at postmortem. Enterocolitis can rapidly progress and be fatal in short-segment Hirschsprung's disease.

Results of 24-h manometric recording of colonic motor activity with endoluminal instillation of bisacodyl in patients with severe chronic slow transit constipation

The aims of this study were to assess the prevalence of manometric colonic abnormalities and to evaluate the motor effect of intraluminal bisacodyl in a cohort of refractory constipated patients. Twenty-four hour colonic motility recordings were performed in 40 patients referred for a severe intractable chronic constipation. At the end of each recording session the motor effects of the endoluminal instillation of 10 mg bisacodyl were assessed. These patients were compared with 20 healthy subjects. The number of high-amplitude propagating contractions (HAPC) was significantly decreased in patients with slow transit constipation (12 +/- 11.6 vs 1 +/- 8.6, P < 0.001). Based on manometric patterns four groups of patients were isolated. Ten patients had no spontaneous HAPC, no food-induced colonic motor response and significantly lower colonic activity in transverse colon (374 +/- 1220 vs 3249 +/- 3458, P < 0.05). Five patients had significantly increased sigmoid segmental motility (20298 +/- 6364 vs 88780 +/- 3643, P < 0.001) and eight patients had significantly lower number of HAPC without other manometric abnormalities while 17 patients had normal colonic motility recordings. Endoluminal bisacodyl was able to induce HAPCs in all groups of patients. Patients with severe slow transit refractory constipation represented a heterogeneous group and endoluminal bisacodyl was able to promote a propagated motor activity in a majority of patients even in those suspected of having an inert colon.

Colonic regular contractile frequency patterns in irritable bowel syndrome: the 'spastic colon' revisited

BACKGROUND

Irritable bowel syndrome is a frequent gastrointestinal disorder of which the pathophysiological basis is still not completely understood. Among the various proposed mechanisms, colonic motility may play a role, at least in a subset of patients.

AIMS

To investigate the regular colonic contractile patterns in patients with irritable bowel syndrome. Our working hypothesis was that an increase of these patterns in such condition might represent a motility equivalent of the so-called 'spastic colon'.

PATIENTS AND METHODS

Twelve patients of both genders were investigated by means of 24 h colonic manometry, and the results were compared to those from 20 healthy controls. Regular contractile patterns (with frequencies ranging from 2 to 8 per min) were calculated for the entire recording period and in single colonic segments.

RESULTS

Overall, colonic frequency patterns were significantly more frequent in patients than controls (12.6% vs 6.4% of the total contractile activity, P < 0.001); in both groups, the 3 cycles/min frequency was predominant, especially in the sigmoid colon. More than 40% patients displayed a correlation between abdominal pain and occurrence of regular contractile frequencies.

CONCLUSIONS

Abnormal colonic motility may play some role in the pathogenesis of symptoms related to irritable bowel syndrome, with an excess of regular contractile activity related to the so-called 'spastic colon'.

Colonic motor activity in slow-transit idiopathic constipation as identified by 24-h pancolonic ambulatory manometry

Colorectal motor activity in slow-transit idiopathic constipation has not been fully evaluated under physiological conditions. The aim of this study was to evaluate colorectal motor activity in chronic idiopathic constipation using 24-h ambulant pancolonic manometry. Ten healthy volunteers (six females) 19-31 years of age, and eight females 25-46 years of age with slow-transit idiopathic constipation were studied. Motor activity was measured using two custom-made silicone-coated catheters, each with five solid-state pressure transducers. Bowel preparation or sedation was not used. Frequency of high-amplitude propagated contractions was reduced in chronic idiopathic constipation, median 1.9/24 h vs 6/24 h (P = 0.01). Contractile frequency of low-amplitude complexes was reduced throughout the colon in slow-transit idiopathic constipation (P < 0.0001). The interval between contractile complexes was reduced in the transverse colon and splenic flexure (P < 0.0001). This study demonstrates that colonic motor activity is abnormal in slow-transit idiopathic constipation; decreased motor activity leads to a reduction in propulsion of intraluminal contents.

Automated quantitative analysis of nocturnal jejunal motor activity identifies abnormalities in individuals and subgroups of patients with slow transit constipation

OBJECTIVE

Small bowel dysmotility has previously been demonstrated in some patients with slow transit constipation (STC), suggesting a generalized intestinal disorder. However, no study has addressed whether the incidence of small intestinal dysfunction differs between subgroups of patients in this heterogeneous population. Using appropriate methodology, we aimed to determine prospectively the proportion of individuals with abnormal small bowel motility, and to assess whether heterogeneity in terms of pattern of colonic transit delay (based on (111)In diethylene-triamine-pentaacetic acid (DTPA) isotope scintigraphy), or mode of onset (based on clinical history) is of importance.

METHODS

Thirty-seven patients with STC underwent 24-h ambulatory jejunal manometry; data were compared with those obtained in 38 healthy controls. Automated quantitative analysis of seven variables of the nocturnal migrating motor complex was performed, to assess whether differences existed between groups, and whether individual patients had evidence of small intestinal dysmotility, defined as two or more measures of migrating motor complex variables outside the normal range. Four variables differed significantly between STC patients and controls: in phase III, propagation was slower, duration was longer, and contraction amplitude was higher; in phase II, contraction frequency was increased. Seven of 24 patients with a generalized pattern of colonic transit delay had abnormal small bowel motility compared with none of 13 with a left-sided delay (p < 0.04). These included four patients with chronic idiopathic symptoms and three with acquired symptoms. Approximately one third of patients with a generalized delay in colonic transit had evidence of jejunal enteric neuromuscular dysfunction. Individual patients with a left-sided colonic delay did not satisfy the criteria for nocturnal small bowel dysmotility, but as a group, some differences were noted from controls. In contrast to previous reports, evidence of generalized enteric dysmotility may be present irrespective of the mode of onset.

Effects of polyethylene glycol 4000 on 24-h manometric recordings of left colonic motor activity

BACKGROUND

It has been shown that low doses of polyethylene glycol (PEG) 4000 are effective in the treatment of chronic constipation. The aim of this study was to describe the effects on colonic motility of oral PEG 4000 treatment and intraluminal instillation of PEG 4000.

METHODS

Left colonic and rectosigmoid manometric recordings were performed for 27 h in six constipated patients and in six healthy volunteers. At the end of the recording, bisacodyl and PEG 4000 were instilled into the lumen of the colon. To assess the effects of oral administration of PEG 4000 on colonic motility, manometric recordings were also performed in constipated patients after 4 weeks of treatment with PEG 4000.

RESULTS

All patients had significantly more stools during than before PEG treatment. There was no significant difference between the number and the characteristics of high-amplitude propagating contractions (HAPC) or the area under the curve (AUC) before or during treatment with PEG 4000. Intraluminal instillation of PEG induced HAPC in only one patient and in no controls.

CONCLUSION

This study shows that PEG 4000 has no effect on left colonic and rectosigmoid motor activity during oral treatment, despite its clinical effectiveness, or after local instillation.

Existence of a high pressure zone at the rectosigmoid junction in normal Indian men

PURPOSE

A hypertonic, electrically hyperactive segment has been described in the rectosigmoid region mainly in constipated persons. Anatomic or manometric evidence to satisfy the criteria for a sphincter here is, however, inconclusive. We evaluated the pressure profile of the rectosigmoid region in normal Indian men.

METHODS

Fifteen male volunteers with regular bowel habits were studied. Rectosigmoid manometry (1 cm station pull-through) was done in the fasting state using a water-perfused system and three-lumen catheter with radially oriented recording ports 5 cm apart.

RESULTS

Eight volunteers had a zone of high pressure. Proximal extent of this zone was identified as the station with a rise in basal pressure of at least 10 mmHg over the previous station. A further rise of at least 10 mmHg in subsequent distal stations was considered essential for defining the existence of the zone. This zone had a median length of 3 cm, with midpoint at median 18 cm from the anal verge and median highest pressure of 36 mmHg. There was no antegrade pressure gradient across the zone; rectal pressures were higher than those in the sigmoid in 12 of 15 volunteers.

CONCLUSIONS

Approximately one-half of normal Indian men with regular bowel habits have a high pressure zone in the rectosigmoid region. The role of diet or defecation posture in its etiology and its effect on bowel habit need to be studied.

Human colonic motility: physiological aspects

From the point of view of its motor activity, the human colon is probably the least understood of the abdominal hollow viscera. This is due to several facts: a) its proximal portions are relatively inaccessible due to anatomical reasons; b) there is no reliable animal model due to the considerable anatomic-physiological differences among mammals. For instance, most deductions about human colonic motor activity have been drawn from experiences in cats and dogs, in which the colon displays a cecum which is almost atrophic, and the viscus is featureless and C-shaped, without the haustrations and the sharp angulations seen in man, c) the wide fluctuations of motility in the daily time course of the same individual makes the interpretation of many studies difficult, especially considering the fact that, until recently, most of the studies on human colonic motility have been conducted for relatively short (30-180 min) recording periods. Recently, however, techniques that allow recording from the proximal portions of the human colon have been developed, and prolonged (24 h or more) observations of myoelectrical and contractile events have been achieved, thus improving our knowledge of the normal physiologic properties of the viscus. These informations have furthermore been integrated and confirmed by scintigraphic techniques (less invasive), that allow the measurement of intracolonic flow activity. The purpose of the present paper is to review the physiological aspects of colonic motility in man, quoting animal studies where human ones are lacking. We will briefly introduce some basic concepts, then a more detailed description of the main topic will follow.

Obstructive defaecation and slow transit constipation: the proctographic parameters

Twenty-two patients with functional obstructive defaecation were compared with seven patients with slow transit constipation using isotope proctography. The obstructive defaecation patients were unable to perform a complete rectal evacuation (% of the activity evacuated: 54%). The defaecation time in this group was prolonged (120 s) with a lower defaecation rate (0.5%/s) compared with the slow transit constipation subjects (32 s and 1.8%/s). The anorectal angle (ARA) on straining did not change in the obstructive defaecation patients but became more obtuse in the slow transit constipation subjects (P < 0.02). The pelvic floor (PF) descent on straining and evacuation was greater in obstructive defaecation patients compared with the slow transit constipation ones (P < 0.01). Obstructive defaecation is characterised by prolonged defaecation and reduced defaecation rate compared with slow transit constipation. Obstructive defaecation patients present with more acute ARAs on straining, and abnormal perineal descent in contrast to the slow transit constipation ones.

Effect of food and anti-cholinergic drugs on the pattern of rectosigmoid contractions

The colonic response to a meal is often used to test the effect of drugs on colonic motility, but this test is hindered by its inconsistency. This study has used multiple manometric sensors situated in the rectosigmoid region to investigate whether recording of the site and type of contraction offers a clear discrimination of the colonic response to a meal and the effect of drugs. Two studies were carried out on 16 healthy volunteers. Before the meal, rectosigmoid motility consisted mainly of isolated contractions occurring in a single manometric channel. The motility index increased in every subject after the meal (p < 0.05), but this increase entirely consisted of a massive increase in contractions occurring simultaneously in three or more manometric channels (multiple channel contractions), the number increasing from 9 per hour preprandially to 57 per hour (p < 0.01). There was a concomitant decrease in the number of the single channel contractions from 65 to 56 per hour. In a second study an infusion of an antispasmodic drug, mebeverine hydrochloride, into the sigmoid colon of healthy volunteers stopped the postprandial increase in the multiple channel contractions and prevented the significant rise in the motility index. The decrease in single channel contractions was unaffected. These results show that the colonic response to a meal consists of a change in the pattern of rectosigmoid contractions and suggest that multiple channel contractions may be a more sensitive indicator of the effect of a meal on the rectosigmoid colon than the motility index.

Impaired colonic motor response to cholinergic stimulation in patients with severe chronic idiopathic (slow transit type) constipation

Chronic idiopathic constipation, especially the slow transit type, is a troubling problem often afflicting young women. The pathophysiological basis for this entity is unknown, although a defective cholinergic innervation has been postulated. We tested the hypothesis that cholinergic colonic innervation is deranged in this condition by studying colonic motor activity after strong cholinergic stimulation with edrophonium chloride in 14 women complaining of slow transit constipation. Unlike healthy subjects, constipated patients showed minimal or no response to edrophonium injection. It is concluded that in slow transit constipation there is an important alteration of colonic cholinergic activity and that edrophonium chloride may represent a useful test drug for colonic pathophysiological investigations.

Effect of eating on colonic motility and transit in patients with functional diarrhea. Simultaneous scintigraphic and manometric evaluations

The aim of this study was to correlate colonic motility with transit in 8 patients with functional diarrhea compared to 12 healthy subjects. Intraluminal pressure was measured with perfused catheter ports in the transverse colon, splenic flexure, and descending and sigmoid colons. Transit of the luminal contents was measured by following the movement of 99mTC-diethylenetriaminepentaacetic acid instilled as a bolus in the splenic flexure. In patients with diarrhea, the intraluminal marker moved in and out of the transverse and sigmoid colon regions of interest during fasting, unlike healthy subjects, in whom the marker remained in the splenic flexure. After eating, radioactivity immediately increased in both the transverse and sigmoid colons in healthy subjects. In the patients with diarrhea, eating did not alter the marker movement into the different regions of the colon compared with fasting. Within 100 minutes of eating, the intraluminal marker almost disappeared from the regions of interest in patients with diarrhea. Postprandial colonic nonpropagating contractions increased in each region of the colon in healthy subjects; there was only a small postprandial increase in colonic motility in patients with diarrhea. However, the numbers of fasting and postprandial propagating contractions were increased in patients with diarrhea compared with healthy subjects (P less than 0.02). Each propagating contraction moved more tracer in patients with diarrhea than in healthy subjects (P less than 0.05). These studies suggest that (a) in patients with diarrhea, the fluctuation of marker in both transverse and sigmoid colons during the fasting and postprandial periods is associated with decreased nonsegmenting contractions and frequent propagating contractions; and (b) in healthy subjects, the intraluminal marker moved after eating because of a pressure gradient caused by nonpropagating contractions.

Colonic motility in humans--a growing understanding

As yet, there is limited information about the relationship of colonic motility to colonic flow or transit. The overall flow in the colon is slow and highly variable. The measurement of total and segmental transit time is essential for the differentiation of motor disorders associated with delayed transit. Rapid movements of colonic contents (mass movements) occur only a few times during the day. Their motor equivalent is the giant contraction which migrates in the aborad direction at relatively high velocity. Motor activity in the colon is highly variable, with periods of contraction and motor quiescence. Contractions occur at different frequencies ranging from 2 to 13 cycles per minute. High frequency contractions are stationary. Their myoelectrical equivalent is short spike bursts. Long spike bursts result in sustained, low frequency contractions, which may migrate in both directions. Technological advances now make it possible to obtain ambulant manometric recordings from the colon for 24 h. Such studies show a circadian variation in colonic motility with increases of activity after meals and after awakening. Motor disorders of the colon are not associated with specific abnormal motor patterns. Rather, they are due to changes in the occurrence of motor patterns seen in health. In constipated patients with slow colonic transit the suppression of strong peristaltic activity is the most plausible common pathogenetic mechanism. In diarrhoeal states, propulsive activity such as the giant migrating contractions may be a major mechanism which promotes the passage of stools. There is no agreement that there is disordered basal colonic motor activity in IBS. There is, however, increasing evidence that in IBS the colon responds abnormally to eating, certain forms of stress and distension, and that this may relate to symptoms. The psychopathology of IBS patients is apparently the most important factor in the health care-seeking behaviour of the patients. No specific therapy has yet been shown to be convincingly effective.

Relationship between outlet obstruction constipation and obstructed urinary flow

Ten women with symptoms and radiological features of outlet obstruction constipation underwent urodynamic bladder studies. The results were compared with ten age- and sex-matched controls. The mean (s.e.m.) peak flow rate for patients was 19.4 (6.4) ml/s compared with 32.1 (7.2) ml/s for controls (P less than 0.05). The mean (s.e.m.) voiding time for patients was 62.9 (23.7) s against a corresponding value of 15.6 (6) for controls (P less than 0.05). The mean (s.e.m.) bladder volume in patients was 482 (80) ml compared with a control value of 254 (112) ml (P less than 0.03). The mean (s.e.m.) detrusor pressure during the voiding phase was 53.3 (12) cmH2O. These results demonstrate that patients with outlet obstruction constipation have a generalized pelvic floor disorder resulting in obstructed urinary flow.

Increased segmental activity and intraluminal pressures in the sigmoid colon of patients with the irritable bowel syndrome

Intraluminal pressure activity has been recorded in the unprepared true sigmoid colon of seven normal controls (mean age 37 years, range 22-55, three men) and seven patients with irritable bowel syndrome (IBS) (45 years, 24-75, four men) for 30 minutes before and 100 minutes after a standard 1000 kcal meal. Results differ from previously published data by showing much higher indices of pressure activity with amplitudes up to 490 mmHg in IBS, and 450 mmHg in controls. Study segment activity index and mean pressure wave amplitudes were significantly (p less than 0.015 and p less than 0.01) higher in IBS than controls, but per cent duration of activity was similar for the whole period of study. During the basal period in controls mean amplitudes recorded from the proximal sigmoid (40 cm from anus) were significantly (p less than 0.01) higher than those in the descending colon (50 cm), distal sigmoid (30 cm) and rectum (15 cm). This study shows that the increased colonic activity in IBS is characterised by increased amplitude, but not duration of pressure waves. In the basal state there is a high pressure zone in the proximal sigmoid colon of controls. Pressures in the unprepared colon of controls and IBS were higher than those measured under other experimental conditions.

Neurophysiological dysfunction in young women with intractable constipation

Fifteen women with intractable chronic idiopathic constipation dating from adolescence were investigated by anorectal manometry, neurophysiological evaluation of the conus medullaris and external anal sphincter. Comparison was made with 25 asymptomatic female control subjects. Urological disturbances were common amongst the constipated, in five of whom incidental lumbosacral spinal dysraphism was found. No differences in sphincter pressures or the rectosphincteric reflex were demonstrable between the two groups. Rectal defecatory sensation was blunted and the compliance was increased in the constipated group. The latency of the pudendo-anal reflex was significantly prolonged in idiopathic constipation, two women having an absent reflex (greater than 100 ms). Mean motor unit potential duration of the external anal sphincter was not significantly prolonged in the eight constipated women tested. A central neurogenic deficit is postulated in some women with this disorder.

Encopresis and constipation in children

Chronic retentive constipation in children is common, often undertreated, and frequently resistant to standard treatment. A new understanding of abnormal defecation dynamics has evolved to complement the established medical behavior model of this condition. The primary care pediatrician is in an excellent position to facilitate prevention through counseling on normal bowel habits and early intervention. A comprehensive medical behavior intervention program can be supervised effectively by the pediatrician providing benefit to most patients. Those who are compliant with treatment and are resistant to intervention may benefit by extensive evaluation of anorectal dynamics and use of such teaching as biofeedback training.

Colonic myoelectrical activity in IBS painless diarrhoea

Colonic myoelectrical activity was recorded during 24 hours in 23 patients with painless diarrhoea and compared with a control group of 10 healthy subjects without digestive functional disorders. Diurnal fasting activity showed no significant difference in the total long spike bursts activity (LSB lasting greater than 7 seconds), but short spike bursts activity (SSB, lasting less than 7 seconds) was significantly lower (p less than 0.05) in diarrhoeal patients. A striking difference was observed in colonic response to eating, with an increased number of migrating long spike bursts (MLSB: mass movements) during the first postprandial hour in diarrhoeal patients (p less than 0.001), while short spike bursts (segmental activity) were almost absent in the rectosigmoid area. A marked decrease in the retrograde LSB activity was also observed in eight patients. During the night (from 2200 h to 0600 h) the number of migrating long spike bursts was increased in the diarrhoea group, but almost absent in controls (p less than 0.001). This study shows that colonic motor activity was altered in painless diarrhoea. These disturbances were not limited to the decreased SSB activity in the sigmoid, but involved the whole colon, with lower SSB activity and abnormal increase of migrating long spike bursts activity (MLSB) in postprandial and nocturnal periods.

Irritable bowel syndrome (IBS)--definition and pathophysiology

The article presents some individual perceptions of the nature of the disease we call the Irritable Bowel Syndrome (IBS), and attempts to rationalise the variable presenting features, the influence of the psyche and the lack of pathological or biochemical markers. Among the topics discussed include the existence of recognisable subsets of the disease, the influence of mental stress, and the pathophysiology of the presenting symptoms. My impression is that IBS is a condition, in which the gut is hypersensitive and hyper-reactive to mechanical and chemical stimuli and as such, can be compared with asthma in the respiratory system. This hyper-reactivity could be caused by increased mucosal permeability, increased numbers and/or responses of effector cells such as mast cells or enterochromaffin cells, and enhancement of intrinsic nerve reflexes by increased activity of efferent vagal fibres.

Physiologic study of the terminal digestive tract in chronic painful constipation

A manometric study of the sigmoid colon and of the anorectum was undertaken in 65 chronically constipated patients complaining of abdominal pain, and in a control group of 23 healthy volunteers. Rectal compliance was tested in both groups. The sigmoid motility study allowed for the segregation of the constipated patients into three groups: hypokinesia (12 cases), normokinesia (34 cases), hyperkinesia (19 cases). Rectal manometry showed anal hypertony in 24 patients, impaired rectal conscious sensitivity in 12 subjects, and normal functions in the remaining cases. The rectal compliance study disclosed a decreased compliance in 15 cases and increased compliance in 13 other patients. In 12 cases disordered sigmoid motility was the only abnormality; in 10 cases only a rectoanal abnormality was found. Most of the patients (52%) exhibited miscellaneous disorders. In contrast, all parameters were normal in nine subjects. No consistent pattern of motility disorders was thus demonstrated in this clinically homogeneous group of patients with chronic, painful, constipation.

Impairment of defecation in young women with severe constipation

Anorectal manometry, radiology, and tests of simulated defecation were carried out in 14 severely constipated young women and 29 age-matched controls. The resting anal sphincter pressures were reduced in the patients, but the squeeze pressures, rectoanal inhibitory reflex, and rectal pressures upon balloon distention were all normal. At rest, the anorectal angle was more obtuse in the constipated group, but there was no overall increase in perineal descent in constipated patients compared with controls. The presence of a balloon in the rectum and the onset of pain were perceived in constipated patients at volumes that were not significantly different from those in normal volunteers. Constipated patients, however, required higher rectal volumes to induce the desire to defecate and to stimulate regular rectal contractions. Constipated patients also found it more difficult to pass simulated stools from the rectum than the normal controls and, unlike most normal controls, failed to inhibit their external anal sphincter on attempted defecation. These findings suggest that young women with severe constipation have great difficulty initiating the coordinated set of events that constitute a normal defecation response.

Diurnal changes in myoelectric spiking activity of the human colon

Using an intraluminal probe supporting eight groups of electrodes, the myoelectrical activity of the proximal, transverse, and distal colon was recorded during 24-h sessions in 10 healthy subjects receiving evening and noon meals (greater than 800 kcal) and breakfast (less than 300 kcal). At each colonic site considered, the electromyograms exhibited two kinds of spike bursts: (a) short spike bursts localized at one electrode site and appearing rhythmically at a frequency of 10.6 +/- 0.3/min and (b) long spike bursts isolated or propagated orally or aborally. A peculiar pattern consisting of nearly permanent short spike bursts at a rate of 6.7 +/- 0.4/min was observed at the rectosigmoid junction. Computerized analysis of the duration of each kind of spike burst showed that the long spike burst activity increased by 63%-129% (p less than 0.05) during 2 h after each meal (but not after breakfast) at each colonic site. Furthermore, a significant (p less than 0.05) decrease in the long spike burst but not short spike burst activity was observed during sleep. These results provide evidence for circadian variations of colonic motility associated with eating and sleeping in the healthy human.

The effect of glucagon and glucagon 1-21 on anal sphincter function

Resting anal sphincter pressure and rectoanal reflex were studied in six healthy volunteers after administration of placebo, glucagon, and glucagon 1-21. Glucagon resulted in a marked but short-lived early decrease in resting anal pressure, whereas the 1-21 fragment of the glucagon molecule had no effect. Further investigation of the possible hormonal/peptidergic regulation of anal sphincter function is necessary.

Different patterns of intestinal transit time and anorectal motility in painful and painless chronic constipation

Anorectal motility and gastrointestinal transit time were studied in 25 patients complaining of non-organic constipation. Colonic pain was reported by 14 patients, it was absent in the remaining 11. The group with painful constipation was composed of four men and 10 women and age onset of the symptom was 22.1 +/- 5.1 years. The other group was composed only of women and painless constipation was reported to have begun at 7.9 +/- 2.2 years previously. In the group presenting painful constipation higher values of the anal maximum resting pressure, of the amplitude of the rectoanal inhibitory reflex, lower values of sensation threshold, need to evacuate, maximum tolerable volume were recorded, in comparison with those registered in the painless constipation group. All these differences were significant. In the latter group the total transit time was always very slow (186.0 +/- 4.7 h), while it was quite variable in the other group, so that the mean was in the normal range (79.0 +/- 10.0 h). The data show that two different patterns of motor abnormalities can be recognised in constipated patients. The presence of colonic pain can suggest the characteristics of the underlying motor abnormality.

Lack of sensitivity and specificity of the renal clearance of amylase/clearance of inulin ratio in experimental acute rat pancreatitis with a study on the renal handling of amylase

As there are controversies about the specificity and the sensitivity of the amylase clearance/inulin clearance ratio (Cam/Cin) in the diagnosis of pancreatitis, this ratio has been calculated: (a) in rats with induced pancreatitis with histologically proven lesions; (b) in toxic induced tubulopathy rats with lesions demonstrated histologically and biologically (enzymuria). Hyperamylasaemia was found in 86% of the pancreatitis rats at 24 h, 50% at 48 h and 25% at 60 h. The ratio Cam/Cin was elevated above 2 SD of the control values among 14% of the rats at 24 h, 50% at 48 h and 25% at 60 h. There were no changes in enzyme elimination rates in the urine as compared to control values. Renal histology remained normal. Histological scores expressing a severe haemorrhagic pancreatitis were identical at 24, 48 ad 60 h. In toxic induced tubulopathy rats, amylasaemia remained normal. but the Cam/Cin ratio only increased when the glomerular filtration rate was diminished by 90%. The diagnosis could only be made by hyperamylasaemia in 50% of the histologically proven pancreatitis in the rat. The use of the ratio Cam/Cin does not increase the frequency of a correct diagnosis. Finally, amylase must be only filtered by the kidney as no tubular enzymes appeared in the urine of pancreatitis rats. Furthermore, this ratio is not specific for pancreatitis as it could be elevated in other pathologic states such as severe renal failure.

Irritable bowel syndrome: physiological and psychological differences between diarrhea-predominant and constipation-predominant patients

Patients with different irritable bowel symptoms and normal subjects were compared to determine whether subtypes of irritable bowel syndrome (IBS) could be distinguished on the basis of colonic motility or psychological test scores. A provocative test involving stepwise distension of the rectosigmoid area revealed two types of colonic motility. Slow contractions having durations of at least 15 sec and occurring at irregular intervals were more frequent in IBS patients than in normals but did not differentiate constipation from diarrhea. Fast contractions having durations of less than 15 sec and occurring in runs at frequencies of 6-9 cpm were more frequent in patients with diarrhea than in normals or constipated IBS patients. Constipated patients showed no more fast contractions than normals. Severity of bowel symptoms was correlated with the overall amount of motility (motility index) in patients with diarrhea but not in patients with constipation. Patients with IBS showed significantly elevated levels on the following psychological traits: anxiety, interpersonal sensitivity, depression, hostility, and somatization of affect. However, there were no significant trait differences between patients with diarrhea and those with constipation. Also, there was no correlationbetween amount of psychopathology and either colonic motility or severity of symptoms in the whole group of IBS patients.

A clinical trial of trimebutine (Mebutin) in spastic colon

Twenty adult Indian patients suffering from the spastic form of irritable colon, i.e. abdominal pain and constipation, were given trimebutine (Mebutin), 2-phenyl, 2-dimethylamino-n-butyl 3, 4, 5-trimethoxybenzoate. Patients were given treatment with 200 mg trimebutine three times daily, or placebo for 4 weeks, and then crossed over. In addition, stool transit times were assessed by the single stool transit time (SST) method of Cummings. Results showed a statistical improvement in abdominal pain and constipation with both trimebutine and placebo after 4 weeks, but only with trimebutine after 8 weeks. Single stool transit time was significantly reduced after trimebutine.

Gastrointestinal radiography with glucagon

This report summarizes the results of nine diagnostic radiographic studies done double blind crossover comparing glucagon to placebo and to anticholinergic drugs in volunteers. In seven studies the subjects were administered drug intramuscularly and in two studies intravenously. There were five diagnostic studies of the upper gastrointestinal tract, one for esophageal varices and three of the colon. The results indicate that glucagon can be given intramuscularly and intravenously. When given intravenously it has a rapid onset and predictable length of action depending on the dose given. Reports of side effects were few consisting primarily of nausea and or vomiting. These results indicate that glucagon is the drug of choice for hypotonic diagnostic examinations.

Effects of glucagon and secretin on food- or morphine-induced motor activity of the distal colon, rectum, and anal sphincter

The effects of glucagon and secretin on food- or morphine-induced motor activity of the distal colon, rectum, and internal anal sphincter were investigated in 12 healthy subjects. Intraluminal pressure changes were measured using a triple-lumen polyvinyl tube assembly with 3 side orifices. Glucagon, administered intravenously, caused significant inhibition of food- or morphine-induced motor activity of both the distal colon and rectum. In contrast, secretin did not suppress morphine-induced motor activity but did significantly inhibit food-stimulated motor activity of the distal colon. The inhibitory effect of secretin on motor activity of the rectum was insignificant. Morphine, but not food, elevated the pressure of the anal sphincter which was not effected by glucagon or secretin. Hyperglycemia, produced by the infusion of 5% glucose, had no effect on motor activity. These studies demonstrate that glucagon but not secretin, in the doses employed, inhibits morphine-induced motor wave activity of both the distal colon and rectum and that this inhibitory effect is not secondary to hyperglycemia. Furthermore, the rise in anal sphincter pressure is not affected by glucagon or secretin.