Pressure profile of the rectum and anus of healthy persons

Experimental Intestinal Stenosis Alters Crohn's Disease-Like Intestinal Inflammation in Ileitis-Prone Mice

BACKGROUND

Clinical observations indicate that mechanical factors contribute to the expression or recurrence of Crohn's disease. We investigated whether the creation of an intestinal stenosis could alter the severity of the expected Crohn-like ileitis, in a Crohn's disease animal model, the TNF^Δare/+ mouse.

METHODS

Thirty-six, 6-weeks-old TNF^Δare/+ mice, were divided into 3 intervention groups: triple suture, single suture and sham. In the terminal ileum, in the first group, a triple suture stenosis was created, whereas, in the second, a loose suture was placed. Same triple-suture stenosis was performed on twelve wild type mice. All animals were sacrificed at 6 weeks post-operatively and the ileum parts were evaluated histopathologically. A summative total ileitis score was applied in each sample using a bespoke semiquantitative histological scoring system for the Crohn-like changes.

RESULTS

The triple suture stenosis induced significant muscular hypertrophy proximal to interventional site which was more prominent in TNF^Δare/+ than wild type mice. In triple suture group, the total ileitis score was significantly increased proximal to the intervention as compared to the single suture (P: 0.004) and the sham groups (P: 0.013). The total ileitis score distally, was unaffected, regardless of the experimental intervention. Intestinal stenosis did not induce intestinal inflammation in wild type mice.

CONCLUSION

The creation of a stenosis in the terminal ileum of TNF^Δare/+ mice alters Crohn-like inflammation. We assume that mechanical forces, such as intraluminal pressure, may contribute as important co-factors to the pathophysiology of Crohn's disease in genetically predisposed subjects.

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.

Anismus, Physiology, Radiology: Is It Time for Some Pragmatism? A Comparative Study of Radiological and Anorectal Physiology Findings in Patients With Anismus

Purpose

Anismus is a functional disorder featuring obstructive symptoms and paradoxical contractions of the pelvic floor. This study aims to establish diagnosis agreement between physiology and radiology, associate anismus with morphological outlet obstruction, and explore the role of sphincteric pressure and rectal volumes in the radiological diagnosis of anismus.

Methods

Consecutive patients were evaluated by using magnetic resonance imaging proctography/fluoroscopic defecography and anorectal physiology. Morphological radiological features were associated with physiology tests. A categorical analysis was performed using the chi-square test, and agreement was assessed via the kappa coefficient. A Mann-Whitney test was used to assess rectal volumes and sphincterial pressure distributions between groups of patients. A P-value of <0.05 was significant.

Results

Forty-three patients (42 female patients) underwent anorectal physiology and radiology imaging. The median age was 54 years (interquartile range, 41.5–60 years). Anismus was seen radiologically and physiologically in 18 (41.8%) and 12 patients (27.9%), respectively. The agreement between modalities was 0.298 (P = 0.04). Using physiology as a reference, radiology had positive and negative predictive values of 44% and 84%, respectively. Rectoceles, cystoceles, enteroceles and pathological pelvic floor descent were not physiologically predictive of animus (P > 0.05). The sphincterial straining pressure was 71 mmHg in the anismus group versus 12 mmHg. Radiology was likely to identify anismus when the straining pressure exceeded 50% of the resting pressure (P = 0.08).

Conclusion

Radiological techniques detect pelvic morphological abnormalities, but lead to overdiagnoses of anismus. No proctographic pathological feature predicts anismus reliably. A stronger pelvic floor paradoxical contraction is associated with a greater likelihood of detection by proctography.

Peptidergic innervation of the internal anal sphincter in Hirschsprung's disease

The pathophysiology of the impaired sphincter function in Hirschsprung's disease is still unclear. The peptidergic innervation of the aganglionic large intestine is known to be disturbed. The present study analyzes the peptidergic innervation of the aganglionic internal anal sphincter (IAS) in comparison with that of the circular layer of ganglionic and aganglionic large intestine. Immunoreactivity for the following substances was analyzed: vasoactive intestinal polypeptide (VIP), substance P (SP), met-enkephalin (ENK), calcitonin gene-related peptide (CGRP), somatostatin (SOM), and neuropeptide Y (NPY). All patients were operated upon with Soave's endorectal pull-through technique and a posterior partial myectomy of the IAS. For comparison, specimens of resected IAS from adult patients operated upon for rectal cancer as well as autopsy specimens from a 2-year-old child were analyzed. Differences in the density of nerve fibers between the ganglionic and aganglionic large intestine were in accordance with previous studies. In sections of normoganglionic IAS moderately dense networks of nerve fibers immunoreactive for NPY, SOM, and VIP were observed. The occurrence of NPY and SOM was somewhat more frequent here compared to the colonic circular muscle coat, whereas the opposite was seen for VIP. In aganglionic IAS abundant nerve fibers immunoreactive for NPY, SOM, and VIP were observed. Only a few SP-, CGRP-, and ENK-immunoreactive fibers were found in normal and aganglionic IAS. It is concluded that there were moderate differences in the peptidergic innervation of the aganglionic IAS as compared to the normal ganglionic IAS and the circular muscle coat of the ganglionic and aganglionic large intestine.

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.

Flatus-related colorectal and anal motor events

Although complaints of excessive "gas" symptoms are frequently encountered in clinical practice, the physiologic and pathophysiologic grounds of flatus events are poorly understood, partly because of the social taboos associated with the topic and partly because of technical difficulties in measuring flatus. For these reasons, we studied the colorectal and anal motor events occurring during artificially evoked flatus events and compared them to those that occurred spontaneously. Five healthy male volunteers were studied by multilumen probes placed in the left colon and rectum and across the anal canal, to observe the flatus-related motor events that occurred after instillation of air into the colon. Flatus-related spontaneously occurring motor events were also checked in 24-hr motility tracings obtained in three patients with functional bowel disorders. Analysis of the tracings showed that both artificially induced and spontaneously occurring flatus-related motor phenomena were characterized by colonic propagated contractions associated with a rise in rectal pressure and early relaxation of the anal sphincter, in a sequence resembling that observed following swallowing. Spontaneous flatus events were associated with colonic waves of lesser amplitude than those following insufflation of air into the colon.

Anorectal function

A review in a historic perspective of the present knowledge of anorectal physiology is presented. The techniques used in the anorectal physiology laboratory are discussed. Application of new sophisticated techniques to anorectal physiology research in recent years continue to improve our knowledge of anorectal function. Anal continence and defecation depend on both the anal sphincter and the rectum. The assessment of patients with functional anorectal diseases should include a more complete physiologic evaluation of the anorectum than used previously.

Rectal suppository: commonsense and mode of insertion

Rectal suppository is a well-known form of medication and its use is increasing. The commonest shape is one with an apex (pointed end) tapering to a base (blunt end). Because of a general lack of information about mode of insertion, we asked 360 lay subjects (Egyptians and non-Egyptians) and 260 medical personnel (physicians, pharmacists, and nurses) by questionnaire which end they inserted foremost. Apart from 2 individuals, all subjects suggested insertion with the apex foremost. Commonsense was the most frequent basis for this practice (86.9% of lay subjects and 84.6% of medical personnel) followed by information from a relative, a friend, or medical personnel, or from study at medical school. Suppository insertion with the base or apex foremost was compared in 100 subjects (60 adults, 40 infants and children). Retention with the former method was more easily achieved in 98% of the cases, with no need to introduce a finger in the anal canal (1% vs 83%), and lower expulsion rate (0% vs 3%). The designer of the "torpedo-shaped" suppository suggested its insertion with apex foremost. Our data suggest that a suppository is better inserted with the base foremost. Reversed vermicular contractions or pressure gradient of the anal canal might press it inwards.

Transducer manometry and the effect of body position on anal canal pressures

Anal canal manometry is performed conventionally with balloons, sleeves, perfused or nonperfused open-tipped catheters, or with multiport probes. The authors constructed a new manometer with four transducers embedded in a probe (15 mm outside diameter) and oriented radially, 90 degrees apart. The transducer probe was validated in 27 healthy volunteers by comparing its performance to that of a standard four-port perfused manometer and then used to measure anal canal and rectal pressures in body positions more physiologic (standing, sitting) than that usually employed (left lateral) for such measurements. Both devices measured similar anal canal resting pressure in the left lateral position (mid canal, 58 +/- 3 mm Hg perfused vs. 62 +/- 4 mm Hg transducer; P greater than 0.05). The transducer probe, however, recorded higher squeeze pressures (mid canal, 100 +/- 6 mm Hg perfused vs. 143 +/- 14 mm Hg transducer; P less than 0.05). The transducer probe detected higher intrarectal and resting anal canal pressures when subjects were standing or sitting, compared with the left lateral position (rectum, 3 +/- 1 mm Hg left lateral; 17 +/- 2 mm Hg standing; 20 +/- 1 mm Hg sitting; P less than 0.05; mid anal canal, 57 +/- 3 mm Hg left lateral; 86 +/- 4 mm Hg standing; 81 +/- 5 mm Hg sitting, P less than 0.05). The rise in resting anal canal pressure was uniform circumferentially. Neither anal canal length nor squeeze pressure changed with change in position. The authors concluded that 1) transducer manometry recorded similar resting but higher squeeze pressures compared with perfused manometry; 2) transducer manometry recorded the same radial variation in anal canal resting and squeeze pressures as that recorded by the perfused manometer; and 3) standing and sitting caused a four-fold rise in intrarectal pressure, which was associated with a concomitant rise in resting anal canal pressure.

Prolonged anorectal manometry and external anal sphincter electromyography in ambulant human subjects

We have developed a method for prolonged combined anorectal manometry and electromyography (EMG) of the external anal sphincter in ambulant subjects. Fourteen healthy volunteers were studied for a total of 284 hr (mean of 20.3 hr/subject). Anorectal manometry was performed using a probe with twin pressure sensors. EMG was recorded by one indifferent and two differential silver-silver chloride surface electrodes positioned 0.5-0.75 cm from the anus on either side. The sampling reflex occurred frequently and was significantly (P less than 0.001) more common during wakefulness than during sleep and also following meals than during fasting (P less than 0.01). The passage of flatus was associated with transient relaxation of the anal canal in 19% of episodes. In contrast, there was a contractile episode with no preceding relaxation in 75% of episodes. The anal sphincter had significantly (P less than 0.05) more action potentials (APs) during the day (12.8 +/- 3.2 APs/10 min) than at night (1.6 +/- 1.3 APs/10 min). During micturition, anal canal pressure rose (mean 15 mm Hg) in association with powerful external anal sphincter contractions. Our data show that, normally, contractile activity both in the anal canal and external anal sphincter maintains fecal continence during micturition and the passage of flatus. The technique should lead to a better understanding of the normal mechanisms of fecal continence during waking and sleep and of the pathophysiology of disorders of anorectal function.

Pelvic floor physiology

Pelvic floor physiology is poorly understood. The funnel shape of the pelvic floor and anal canal is uniquely developed to provide discriminatory continence of gas, liquid, and solid. Proximally, the pelvic floor consists of the pubococcygeus and iliococcygeus muscles. Distally, the anal canal is surrounded by the internal and external sphincter muscles. The anorectal ring is situated between the proximal pelvic floor and the distal anal canal. It is the site of the puborectalis muscle, which is anatomically, neurologically, and functionally merged with the deep portion of the external sphincter muscle. It is at this site that unique forces act to create both a flutter valve and the anorectal angle with the flap valve. Extrinsic pressures at this level reinforce both the flap valve and the flutter valve. Intrinsic pressures are generated by all of the surrounding muscles to produce a high-pressure zone. These factors are critical, but many other factors, such as rectal capacity, compliance, colonic transit, motility, and sensory mechanisms, also interact in a complex way to provide normal continence and defecation. Not surprisingly, no single test allows a complete assessment of the interactions of all these factors. Nevertheless, analysis of components thought to be important in pelvic floor physiology has contributed significantly to the understanding of normal as well as abnormal physiology. Although clinical evaluation continues to be the cornerstone of the diagnosis of pelvic floor disorders, anorectal physiological testing has contributed significantly to our understanding of the dynamics of the pelvic floor. With the refinement of existing techniques and the addition of new investigative tools, it is anticipated that knowledge of pelvic floor physiology will continue to grow.

Function of the striated anal sphincter during straining in control subjects and constipated patients with a radiologically normal rectum or idiopathic megacolon

The function of the striated anal sphincter during defaecation straining was recorded by manometry and electromyography (E.M.G.) in 31 constipated patients who were unable to expel a water-filled rectal balloon with effort. This group was divided on the basis of measurement of colonic diameter into those with megacolon and those with a normal sized colon. The latter group was further divided into those with normal transit and those with slow transit. The results were compared with those recorded from 15 control subjects with normal bowel function. With straining, anal pressure fell in 12 of 15 controls while in 3 it increased. In 30 of 31 constipated patients, anal pressure rose paradoxically with straining. Electromyographic recording in controls during straining demonstrated decreased activity in 5, in 4 no change and in 5 an increase in activity. In 28 of 31 constipated patients E.M.G. activity increased with straining. These results suggest that external sphincter contraction during straining occurs in some normal subjects but more frequently among patients with constipation of different types.

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.

Assessment of microtransducers in anorectal manometry

It has been reported that microtransducer-tipped catheters (transducer) produce reliable reproducible measurements which correlate well with water-filled balloon systems. Maximum resting pressure (MRP) and maximum voluntary contraction pressures (MVC) were compared using a standard station pull-through technique in 12 patients. There was a poor correlation for both MRP: microballoon, 115 cmH2O (60-160 cmH2O); transducer 60 (20-110), r = 0.62, P less than 0.05, and MVC: microballoon, 202 (60-375); transducer, 175 (60-210), r = 0.42, n.s. To determine whether this was due to radial variation in pressures measured by the transducer, we studied a further 39 patients with both systems. At each station, transducer measurements were made at each of four quadrants. We found better correlation for MRP: microballoon, 100 (40-175); transducer, 66 (34-120), r = 0.72, P less than 0.001, and MVC: microballoon, 225 (55-650); transducer, 180 (50-470), r = 0.87, P less than 0.001, but a significant radial variation for the transducer where rotation reduced MRP pressure measurements by 21 per cent (0-600 per cent), and MVC 17 per cent (0-76 per cent). Moreover there was a significant difference between anterior and posterior MRP in the upper anal canal, anterior 35 (5-80) versus posterior 25 (10-60), P less than 0.05. These results account for the poor correlation between random positioning of the microtransducer-tipped catheter and indicate that radial orientation must be taken into account.

Effect of age, gender, and parity on anal canal pressures. Contribution of impaired anal sphincter function to fecal incontinence

The contribution of the resting anal canal pressure (RAP) and the maximal squeeze pressure (MSP) to the problem of fecal incontinence was assessed by comparing 143 incontinent patients to a control population of 157 healthy subjects. These parameters were determined using a multilumen continuously perfused catheter and a mechanized rapid pull-through technique. In 10 male volunteers both RAP and MSP were determined using catheters that varied from 3 mm to 18 mm in diameter. In the control population, the RAP was significantly lower in females 40 years of age and over as compared to males. MSP values were significantly lower in females at virtually all ages. In women, parity did not correlate with RAP (coefficient = -0.099, P greater than 0.05) and MSP (coefficient = -0.123, P greater than 0.05) and any decrease in pressures was related to aging. Aging in women was associated with a consistent reduction in RAP (coefficient = -0.614, P less than 0.00005) and MSP (coefficient = -0.372, P = 0.0006). In males, there was a similar but less impressive age-related reduction for the RAP (coefficient = -0.333, P = 0.006) but not for the MSP (coefficient = -0.196, P greater than 0.05). Nine percent of the volunteer population were essentially unable to increase the RAP with maximal squeeze efforts. A linear increase in anal pressures was recorded as catheter diameter increased from 3 to 12 mm. Normative data for the RAP and MSP (mean +/- 2 SD) were constructed for each sex on a decade basis and showed a wide range of pressures for each age grouping. In the group with fecal incontinence (FI) 39% of females and 44% of males fell within the "normal" range for both the RAP and MSP. For all patients with FI, 41% and 17% had impairment of one or both parameters, respectively. It is concluded that: aging affects the RAP in both sexes but to a greater degree in women. The MSP is related to aging in women only; child bearing has no effect upon these parameters; clinical problems of bowel control can occur when sphincter pressure measurements are within the low "normal" range; and recording instrument diameter consistently affects RAP and MSP.

Excitatory innervation of the rabbit rectococcygeus muscle by enteric nerves from the terminal large intestine

The rectococcygeus muscle extends from the longitudinal layer of the external muscles of the terminal colon, anchoring the large intestine to the coccygeal vertebrae. The muscle is thought to assist the colon during defaecation, drawing the large intestine partly into the pelvic cavity. In the rabbit, many fine nerves run between the wall of the colon and a ganglionated nerve plexus on the ventral face of the rectococcygeus muscle. Extracellular recordings of evoked and spontaneously occurring multiunit discharges from these nerve bundles indicated that they may take their origin from the enteric nervous system of the large intestine. Enteric nerves (as we have called them) conducted bursts of spontaneously occurring multiunit discharges, each burst associated with a twisting movement of the rectococcygeus and the colon. Electrical stimulation of enteric nerves elicited cholinergically mediated contractions of the rectococcygeus; however, nerve stimulation failed to elicit relaxation of muscle tone induced by carbachol. Therefore, enteric nerves appeared to supply the rectococcygeus with an excitatory innervation only. These excitatory nerves appeared to remain uninterrupted by a ganglion synapse as they travelled to the rectococcygeus. Stimulation of enteric nerves caused the left and right hemirectococcygeal muscle strips to twist and deform the colo-rectal region to which they were attached. From these results, it is suggested that the rectococcygeus may delay the movement of luminal contents from colon to rectum by forming a weak valve which partially occludes the colo-rectal region. The enteric nerves to the rectococcygeus may assist in the maintenance of continence.(ABSTRACT TRUNCATED AT 250 WORDS)

An analysis of anal sphincter pressure and anal compliance in normal subjects

To investigate anal sphincter mechanics, anal pressure was measured in 14 normal males and 11 normal females using probes of 0.4 to 3 cm in diameter. Resting pressure profiles on insertion and withdrawal did not differ significantly. Anteroposterior pressure differences could be explained by leverage of rigid probes against the anterior rectal wall. A maximal voluntary squeeze increased pressure throughout the anus, whereas the recto-anal inhibitory reflex resulted in a greater reduction in pressure in the upper part of the anal canal. Resting pressure, squeeze pressure and minimum residual pressure (during rectal distension) rose with increasing anal diameter. Estimated sphincter tension was linearly related to anal diameter and the slope of this relationship was increased by sphincter contraction and reduced by sphincter relaxation. The deviation from linearity of this relationship at low anal diameters may be due to swelling of the anal cushions to maintain anal pressure when muscular tension approaches zero.

Rectosigmoid sphincter of O'Beirne

In the early 19th century, James O'Beirne proposed that a physiologically important sphincter existed at the rectosigmoid junction. Interest in the rectosigmoid junction had been stirred by a common affliction of the time: spasmodic constriction of the rectum. It was believed that many patients suffered from chronic constipation because of rectosigmoid spasms. O'Beirne proposed that a sphincter at the rectosigmoid junction governed the passage of stool from the sigmoid into the rectum. Further, he maintained that spasmodic constriction of the rectum resulted from dysfunction of this rectosigmoid sphincter. His views, however, conflicted with those of such contemporaries as Houston, who emphasized the role of rectal valves in producing spasmodic constriction. Anatomic studies in the early 20th century found at least a rudimentary sphincter at the rectosigmoid junction in 40 percent of the normal population. Motility studies in the last 35 years have demonstrated unique intraluminal pressure patterns as well as the propagation of retroperistaltic waves in this area. The rectosigmoid in patients with constipation shows an increased activity, as if this area is causing a physiologic obstruction to the passage of stool into the rectum. In contrast, the rectosigmoid in patients with diarrhea demonstrates markedly decreased activity, thereby providing unobstructed access of the feces to the rectum. These studies support O'Beirne's hypothesis that a sphincter governs the passage of stool from the sigmoid colon into the rectum.

Anorectal profilometry with the microtransducer

The reproducibility of anal sphincter manometry has been evaluated in 17 patients with a continuous pull-through technique using a miniature transducer mounted on a 2mm diameter Dacron catheter. Comparison was made with a conventional station pull-through technique using a 4mm diameter waterfilled microballoon connected to an external transducer. Parameters measured with the microtransducer (maximum resting pressure, squeeze pressure, functional sphincter length, area under high pressure zone, amplitude of rectosphincteric reflex) showed mean coefficients of variation from 3.2 to 5.7 per cent. Pressures measured with the microballoon were uniformly higher than those obtained with the microtransducer. The functional sphincter length was significantly shorter when measured with the microballoon (P less than 0.001). The microtransducer provides a highly accurate and reproducible method of anorectal profilometry that avoids many of the drawbacks associated with fluid-filled systems.

A simple method of anorectal manometry

Anorectal manometry is usually performed with an open-tipped tube or a closed balloon system. To overcome the well known measurement problems and errors associated with fluid-filled catheter systems and balloons, a pressure tranducer was used to perform anorectal manometry. This method, performed on more than 200 individuals with different anorectal disorders, is described. This was found to be a simple, reliable and reproducible method for anorectal manometry.

A clinico-physiological comparison of ileal pouch-anal and straight ileoanal anastomoses

The ileal pouch-anal anastomosis improves clinical results after colectomy and mucosal proctectomy compared to the straight ileoanal anastomosis. The question was what physiologic changes brought about by the pouch led to the improvement. Among 124 patients who had had ileoanal anastomosis, 25 volunteered for a detailed clinicophysiologic evaluation. Fourteen had had the ileal pouch-anal operation a mean of 8 months previously, and 11 had the straight ileoanal operation a mean of 25 months previously. Both groups of patients had satisfactory anal sphincter resting pressures (mean +/- SEM, pouch = 68 +/- 8 cm H2O, straight = 65 +/- 9 cm H2O, p greater than 0.05) and neorectal capacities (pouch = 278 +/- 26 ml, straight = 233 +/- 36 ml, p less than 0.05), and all could evacuate spontaneously. However, the pouch patients had a more distensible neorectum (delta V/delta P pouch = 9.5 +/- 1.3 ml/cm H2O, straight = 4.9 +/- 0.9 ml/cm H2O, p less than 0.05) and smaller amplitude neorectal contractions (pouch = 36 +/- 5 cm H2O, straight = 90 +/- 13 cm H2O; p less than 0.05). We concluded that the pouch-anal anastomosis increased the distensibility of the neorectum and decreased its propulsive drive, and so improved clinical results.

Fistula-in-ano. A manometric study

The functional outcome of fistula surgery can be quantitated by anal manometry. A closed, water-filled microballoon (0.5 X 1.0 cm) system was used to measure resting anal pressure and maximal squeeze pressure in 47 patients with anal fistulas at St. Mark's Hospital. After treatment of intersphincteric fistulas, there was a significant reduction in resting pressure in the distal 2 cm. In treated transphincteric fistulas and suprasphincteric fistulas, anal pressure was reduced in the distal 3 cm. A significant lower pressure was measured in patients having the external sphincter divided, compared with those having the muscle preserved. Disturbance of continence was related to abnormally low resting pressure in six patients. This study supports attempts at sphincter preservation in fistula surgery.

Physiologic aspects of continence after colectomy, mucosal proctectomy, and endorectal ileo-anal anastomosis

We examined the physiology of continence in 12 patients at least four months after colectomy, mucosal proctectomy, and endorectal ileo-anal anastomosis for ulcerative colitis and familial polyposis. The mean fecal output (+/-SEM) was 598 +/- 60 gm, passed as 12 +/- 4 movements/24 hr, of which 4 +/- 1 were passed at night. The patients were generally continent during the day and could distinguish gas from stool, but 11 of 12 leaked stools at night. Anal sphincter resting pressures (71 +/- 8 cm H2O) and squeeze pressures (171 +/- 15 cm H2O) of patients were similar to those of ten healthy controls (P greater than 0.05), although the rectal inhibitory reflex was absent in the patients. After operation, the distal bowel had a pressure-volume curve of greater slope (0.15 +/- 0.05 ml/cm H2O) than it had in controls (0.07 +/- 0.01 ml/cm H2O, P less than 0.05) and a lesser maximum capacity (patients, 248 +/- 31 ml; controls, 406 +/- 26 ml; P less than 0.05). The greater the capacity of the neorectum, the fewer was the number of bowel movements/day (r = 0.91, P less than 0.001). We concluded that the operation preserved the anal sphincter, although it decreased the capacity and compliance of the distal bowel and impaired continence.

An assessment of anorectal motility in the management of adult megacolon

Anorectal motility measurements have been performed on 19 patients with adult megacolon and the results compared with 12 normal subjects. Adult Hirschsprung's disease (4 patients) was recognized by the absence of anal canal inhibition on rectal distension (normal mean inhibition 21.9 +/- 2.3 mmHg). Seven patients with non-Hirschsprung's megacolon (idiopathic) had an elevated anal pressure (mean 90.4 +/- 7.0 mmHg). These patients were treated with repeated anal dilatation. Eight further patients had normal anal canal pressures (mean 33.2 +/- 11.7 mmHg) and were treated with enemas and regular suppositories. Little overall clinical improvement resulted in this group and 1 patient underwent subtotal colectomy. Measurements of anorectal motility have been found to assist in the management of adult megacolon.

[Sphincter function after rectal resection with peranal anastomosis (author's transl)]

To test sphincter function after rectal resection with colon-anal anastomosis performed with Park's peranal technique, 17 patients were examined using the Kelly code and manometric studies. Compliance and anal resting pressure were reduced. Sphincter internal relaxation after rectal distension was also less compared to the norm. Continence was normal for 10 patients and 4 had satisfactory function.

Anorectal reflex following sphincter-saving operations

The function of the anal sphincters following anterior resection of the rectum and Bacon type pull-through operation has been investigated. Our data have shown a significant decrease in the anal resting pressure after pull-through excision indicating an impairment in the sphincter function. Nevertheless the sphincter response induced by stretch receptor stimulation can maintain continence.

Anal pressure studies in spinal patients

Maximal and sphincter pressure was measured in 22 patients with spinal cord lesions and in a group of 10 controls, using perfused sleeve manometry. The mean resting pressure of the spinal patients was 63+/-8 (SEM) mm Hg, and of the control group 116+/-14 (SEM) mm Hg, P less than 0-01. When the rectum was distended by a balloon inflated with 100 ml of air a fall in anal sphincter pressure to 33+/-6 (SEM) mm Hg in the spinal group and to 78+/-10 (SEM) mm Hg in the control group was observed.

Characterization of a hyperactive segment at the rectosigmoid junction

During a study of intraluminal motor patterns of the colon and rectum, spontaneous wave activity of a continuous complex type was observed at the rectosigmoid junction in constipated subjects. To assess the frequency and characteristics of this hyperactive segment, 36 subjects with colonic motor disorders and 12 healthy controls were studied. Eighteen of 24 patients with constipation (75%) and 1 of 7 subjects with asymptomatic diverticulosis exhibited a persistent hyperactive segment at the rectosigmoid junction. Neither secretin nor cholecystokinin influenced the wave activity of the hyperactive segment. In contrast, atropine and glucagon inhibited markedly all wave activity and decreased the motility index of this segment significantly, suggesting overactivity of the muscarinic effector cells. It is concluded that a segmental area of overactivity exists at the rectosigmoid junction in most constipated subjects regardless of their underlying disorders.

Measurement of anal pressure and motility

A fine open perfused system and a closed balloon system for the measurement of anal pressure and motility have been compared. Measurements were made in 40 normal subjects and 84 patients with haemorrhoids. The rate of perfusion had a marked effect on the recorded pressure and motility details. The motility pattern was seen most clearly with the balloon probe and the pressure recorded was reproducible and easy to measure, making this a convenient method for recording activity of the internal anal sphincter. Anal motility in normal subjects was characterised by slow pressure waves (10-20/min). The frequency was fastest in the distal anal canal and this frequency gradient may represent a normal mechanism to keep the anal canal empty. Ultra slow pressure waves (0-6-1-9/min) were seen in 42% of patients with haemorrhoids and 5% of normal subjects and arose from a synchronous contraction of the whole internal sphincter.

Manometric studies of anorectal disorders in infancy and childhood: an investigation of the physiopathology of continence and defaecation

Anorectal manometry was performed on 126 infants and children with anorectal dosorders. In addition, 14 normal children were studied. Pressure measurements were taken with two perfused open-tip catheters. The activity of the external and internal balloon was used to distend the rectal ampulla with air.

Manometric assessment of continence after surgery for imperforate anus

Of 49 children with imperforate anus, 23 underwent an abdominoperineal procedure for a high and seven for a low maliformation, 17 had a perineoplasty for a low and two for a high malformation. In each subject, rectal and anal sphincteric resting pressures were studied at least 1 yr after surgery. Of 30 subjects who had undergone an abdominoperineal procedure, eight were continent in contrast to 15 out of 19 patients who had had a perineoplasty (p less than 0.001). In patients who had undergone an abdominoperineal procedure, the rectal motility was of the colonic type, with waves of higher amplitude and lower frequency (p less than 0.01) than in the normal rectum in 23 cases and in most of these, peristalsis was recorded down to the anal margin. Incontinence was most frequently associated with abnormally short anal resistance, low anal pressure, reduced sensibility, weak voluntary contraction and absence of rectoanal inhibitory reflex. In the group of patients who underwent perineoplasty, continence was associated with normal mechanical parameters and normal physiologic behavior of the anal sphincter.

Function of the anal sphincters in patients with intussusception of the rectum

Patients with intussusception of the rectum--six with anal incontinence and nine continent--were examined with respect to the function of the anal sphincters. Anal pressure was recorded continuously during rest, during maximal voluntary squeezing of the anal muscles, and during gradual expansion of the rectum by means of a balloon inserted into the rectal ampulla. The maximal anal pressure at rest, which is mainly due to activity of the internal anal sphincter, was lower (P less than 0-001) in the incontinent patients (31 mmHg +/- 5-6) than the continent (67 mmHg +/- 4-3) and the former had significantly smaller relaxations of the internal sphincter upon rectal distension (P less than 0-05). The increase in anal pressure during voluntary squeezing, a function of the external sphincter, did not differ significantly compared with healthy subjects in either incontinent or continent patients. On the basis of the above findings, it is concluded that the function of the internal sphincter is impaired in the incontinent patients.