Measurement of anal pressure and motility

3D High-definition anorectal manometry: Values obtained in asymptomatic volunteers, fecal incontinence and chronic constipation. Results of a prospective multicenter study (NOMAD)

BACKGROUND

3D-high definition anorectal manometry (3DARM) may aid the diagnosis of functional anorectal disorders, but data comparing asymptomatic and symptomatic subjects are scarce. We aimed to describe 3DARM values in asymptomatic volunteers and those with fecal incontinence (FI) or chronic constipation (CC), and identify which variables differentiate best these groups.

METHODS

Asymptomatic subjects were stratified by sex, age, and parity. Those with FI or CC were included according to anorectal symptom questionnaires. Endoanal ultrasound examination and 3DARM were performed the same day. Anal pressures were analyzed at rest, during voluntary squeeze, and during push maneuver, and compared between the 3 groups. Anal pressure defects were defined and compared to ultrasound defects.

KEY RESULTS

A total of 126 subjects (113 female, mean age 52 years, range 18-83) were included; 36 asymptomatic, 38 FI, 42 CC. Anal resting and squeeze pressures, and rectal sensitivity values were lower in FI women than in the other groups. Typical anal sphincter asymmetry during squeezing was less frequently observed in FI women. A dyssynergic pattern during push maneuver was found in 70% of asymptomatic subjects, and with a similar frequency in the 2 symptomatic groups. There was slight concordance between 3D-pressure defects and ultrasound defects.

CONCLUSIONS & INFERENCES

3D anal pressures in asymptomatic women were significantly lower than in men, and in FI compared to asymptomatic women. The classical dyssynergic pattern during push maneuver was found as frequently in asymptomatic and symptomatic patients. Further studies should try to identify 3DARM variables that could reliably identify dyssynergic defecation.

An In Vivo and In Vitro Evaluation of the Mutual Interactions between the Lung and the Large Intestine

One of the most important theories of the traditional Chinese medicine is the exterior-interior relationship between the lung and the large intestine; so far, little direct experimental evidence has been reported to support such relationship. Here we for the first time investigated the mutual interactions between the lung and the large intestine by examining the relevancies between the pulmonary functions and the rectal resting pressure in the rat models of asthma and constipation. We also evaluated the effects of the lung homogenate and the large intestine homogenate on the isolated large intestine muscle strip and the isolated tracheal spiral, respectively. Our results showed that the pulmonary resistance and pulmonary compliance were closely related to the rectal resting pressure in the asthmatic rat model, while the rectal resting pressure was much correlated with the pulmonary resistance in the rat model of constipation. Moreover, it was shown that the lung homogenate could specifically contract the isolated large intestine muscle strip. Overall, this study provided new lines of evidence for the theory and highlighted the potential application in the treatment of the corresponding diseases.

Stapled transanal rectal resection with contour transtar for obstructed defecation syndrome: lessons learned after more than 3 years of single-center activity

BACKGROUND

Obstructed defecation syndrome is a widespread and disabling disease.

OBJECTIVE

We aim to evaluate the safety and efficacy of stapled transanal rectal resection performed with a new dedicated curved device in the treatment of obstructed defecation syndrome.

DESIGN

A retrospective review of 187 stapled transanal rectal resections performed from June 2007 to February 2011 was conducted.

SETTINGS

The entire study was conducted at a university hospital.

PATIENTS

: All the patients with symptomatic obstructed defecation syndrome and the presence of a rectocele and/or a rectorectal or rectoanal intussusception, in the absence of sphincter contractile deficiency, were included in the treatment protocol.

INTERVENTIONS

All procedures were performed with the use of the Contour Transtar device. We analyzed the functional results of this technique, the incidence and features of the surgical and functional complications, and ways to prevent or treat them.

MAIN OUTCOME MEASURES

Constipation was graded by using the Agachan-Wexner constipation score; use of aids to defecate and patient satisfaction were assessed preoperatively and 6 months after surgery. Intraoperative and postoperative complications were also investigated.

RESULTS

The constipation intensity was statistically reduced from the preoperative mean value of 15.8 (± 4.9) to 5.2 (± 3.9) at 6 months after surgery (p < 0.0001). Of the 151 (80.3%) patients who took laxatives and the 49 (26.2%) who used enemas before treatment, only 25 (13.2%; p < 0.0001) and 7 (3.7%; p < 0.0001) continued to do so after surgery. None of the 17 (9.1%) patients who had previously helped themselves with digitations needed to continue this practice. Almost all patients showed a good satisfaction rate (3.87/5) after the procedure.

LIMITATIONS

Limitations are the short follow-up of 1 year and the design of the study that may introduce potential selection bias.

CONCLUSIONS

The results of this study show that stapled transanal rectal resection performed with the use of the Contour Transtar is a safe and effective procedure to treat obstructed defecation syndrome.

The physiology of human defecation

Human defecation involves integrated and coordinated sensorimotor functions, orchestrated by central, spinal, peripheral (somatic and visceral), and enteric neural activities, acting on a morphologically intact gastrointestinal tract (including the final common path, the pelvic floor, and anal sphincters). The multiple factors that ultimately result in defecation are best appreciated by describing four temporally and physiologically fairly distinct phases. This article details our current understanding of normal defecation, including recent advances, but importantly identifies those areas where knowledge or consensus is still lacking. Appreciation of normal physiology is central to directed treatment of constipation and also of fecal incontinence, which are prevalent in the general population and cause significant morbidity.

Contribution of posture to anorectal manometric measurements: are the measurements in left-lateral position physiologic?

PURPOSE

Anorectal manometry is commonly used to investigate fecal incontinence. Traditional practice dictates that measurements are performed with the patient in the left-lateral position however, episodes of fecal incontinence usually occur in the erect position. The influence of erect posture on anorectal manometry has not been studied.

METHODS

We examined the contribution of posture to commonly measured variables during manometry by performing assessment in the left-lateral position and the erect posture. Maximum mean resting pressure, vector volumes, and resting pressure gradient were compared.

RESULTS

Complete data were available for 172 patients. Median age was 55 (interquartile range, 44-65) years. Thirty-seven (22 percent) patients were continent, and 135 (78 percent) were incontinent. Both resting pressure and vector volume increased significantly in the erect position for both continent (P = 0.008 and 0.001, respectively) and incontinent (P = 0.001 for both) patients. A significant negative correlation was seen between severity of incontinence and resting pressure in the erect posture and amount of change in maximum mean resting pressure from left-lateral to erect posture (Spearman coefficients = -0.203, -0.211, and P = 0.013, 0.017, respectively) but not with maximum mean resting pressure in the left-lateral position (Spearman coefficient = -0.119; P = 0.164).

CONCLUSIONS

Our study shows significant increase in measurements of manometric variables in the erect position. The increase may be related to anal cushions, which have a significant role in this position. The measurements in erect posture are better correlated with severity of incontinence and may be a more physiologic method of performing anorectal manometry.

Impedance planimetric description of normal rectoanal motility in humans

PURPOSE

Manometry and pressure-volume measurements are commonly used to study anorectal physiology. However, the methods are limited by several sources of error. Recently, a new impedance planimetric system has been introduced in a porcine model. It allows simultaneous determination of anorectal pressures and multiple rectal luminal cross-sectional areas. This study was designed to study normal human rectoanal motility by means of impedance planimetry with multiple rectal cross-sectional areas and rectal and anal pressure.

METHODS

Twelve healthy volunteers (10 females), aged 24 to 53 years, were studied during one-hour fasting and one hour after a meal. Rectal cross-sectional areas were determined at five levels each 2 cm apart, as well as rectal and anal pressure.

RESULTS

A number of rectoanal motility patterns were observed. A total of 25 episodes with very localized cyclic rectal contractions detected at only one of five channels were observed lasting two to four minutes with a median frequency of three per minute (range, 2-6). A total of 44 episodes of cyclic rectal contractions propagating over two or more channels were detected lasting 2 to 36 minutes. Most were associated with contractions of the anal canal. A significant increase in rectal contractile activity was observed after the meal (P < 0.05). Single rectal contractions were observed in 11 subjects, and the majority were located to one channel and lasted less than 40 seconds. In two subjects who felt a need to defecate during the experiment, the cross-sectional area at all channels showed strong cyclic contractile activity and the anal pressure increased by approximately 100 percent.

CONCLUSIONS

The new rectal impedance planimetry system allows highly detailed description of rectoanal motility patterns. It has promise as a new method for description of rectoanal motility in further studies.

Anal ultraslow waves and high anal pressure in childhood: a clinical condition mimicking Hirschsprung disease

PURPOSE

Anal ultraslow waves (USWs) have been described in several clinical conditions closely related to chronic constipation associated with high anal pressure; however, USW-related clinical manifestations in childhood are poorly understood. The purpose of this study is to elucidate the clinical relevance of USWs in childhood.

METHODS

Manometric recordings of 118 cases including 70 children with constipation and 16 patients with Hirschsprung disease were analyzed.

RESULTS

Ultraslow waves were seen in 4 of 70 children with constipation. None of the controls or patients with Hirschsprung disease exhibited USWs. The 4 patients comprised 2 infants with marked abdominal distension mimicking Hirschsprung disease and 2 children (aged 4 and 8 years) with intractable constipation accompanying hemorrhoid or anal fissure. The manometric findings of the USW-positive patients showed a markedly high anal resting pressure and high frequency of slow waves compared to controls, patients with constipation not accompanied by USWs or patients with Hirschsprung disease.

CONCLUSION

Children with USWs exhibit symptoms mimicking Hirschsprung disease in infants and chronic intractable constipation in older children. In manometric studies of children, more attention should be paid not only to rectoanal reflex, but also USWs.

Multiple clinical presentations of anal ultra slow waves and high anal pressure: megacolon, hemorrhoids and constipation

The physiopathology of idiopathic chronic constipation is complex and yet to be investigated. In the manometric studies of the patients with severe chronic constipation, we noticed that some patients with megacolon show very slow periodical (< 2/min) pressure change in the anal canal, namely ultra slow waves (USWs). USWs are considered to represent the hyperactivity of the internal anal sphincter; however, USW-related clinical presentations have yet to be investigated. We retrospectively re-evaluated the patient records and manometric studies of 85 cases, 51 subjects without defecatory problems and 34 patients with constipation, to elucidate USW-related clinical presentations. USWs were seen in 10 patients, including eight patients with chronic constipation and two subjects without defecatory problems. Out of the eight patients with constipation, one had no organic change in the anorectum, three had hemorrhoids and four exhibited megacolon. Manometric and pathological studies proved that none of the four patients with megacolon was suffering from Hirschsprung's disease. Among the 51 subjects without defecatory problems, only two had USWs. Anal pressure in the USW-positive group (106.0 +/- 37.0 cmH2O) was significantly higher than that in the group without defecatory problems (56.0 +/- 27.0 cmH2O) or constipated patients without USWs (55.0 +/- 26.0 cmH2O). Megacolon and high anal pressure, as well as chronic constipation and hemorrhoids, were the clinical presentations related to USWs. This is the first report to show the clinical relevance of USWs to megacolon. USWs should be recognized as an important manometric finding indicating a possible new clinical entity in chronic constipation.

Assessment of anal sphincter function by Sengstaken-Blakemore tube anal manometry

BACKGROUND

Anal manometry is a useful tool for testing the effectiveness of surgical treatment. However, most techniques for anal pressure measurement are not easily available because of high cost. The aim of the present study was to introduce an easy and reproducible method for measuring anal pressures in testing the effectiveness of surgical procedures.

MATERIALS AND METHODS

We used a Sengstaken-Blakemore tube connected to a mercury manometer. After calibration of the system by inflating the distal (gastric) balloon and filling connection lines to the mercury manometer with 0.9% NaCl solution, resting and squeezing anal pressures were measured. The system was used on 50 human subjects (35 with anal fissure and 15 normal volunteers). Left lateral internal sphincterotomy had been performed in the anal fissure cases. Anal pressures were measured preoperatively and on postoperative days (POD) 2 and 20.

RESULTS

Preoperative resting anal pressures in the group with anal fissure (83.4 +/- 1 mmHg) were significantly higher than those in the group of normal individuals (52 +/- 1.2 mmHg; p = 0.001). Resting anal pressures after the sphincterotomy (29 +/- 1 mmHg) were found to be significantly lower on POD 2, and resting anal pressure measurements (47 +/- 1 mmHg) on POD 20 were lower than the corresponding preoperative values. These values are closer to those of normal volunteers (p = 0.016).

CONCLUSIONS

Anal manometry can be performed with this easily constructible and inexpensive system. This reproducible method can be used in the assessment of the results of surgical treatment in patients with anal and perianal diseases.

The vascular nature of hemorrhoids

The arterial blood supply of the internal hemorrhoidal plexus is commonly believed to be associated with the pathogenesis of hemorrhoids. Ultrasound-supported proctoscopic techniques with Doppler-guided ligature of submucosal rectal arteries have been introduced for the therapy of hemorrhoids. The present investigation focuses on caliber and flow changes of the terminal branches of the superior rectal artery (SRA) supplying the corpus cavernosum recti (CCR) in patients with hemorrhoids. Forty-one outpatients (17 female, 24 male; mean age 48 years) with hemorrhoids of Goligher grades I-IV were compared with 17 healthy volunteers (nine female, eight male; mean age 29 years) by means of transperineal color Doppler ultrasound. The mean caliber of the arterial branches in the study group with hemorrhoids was 1.87 +/- 0.68 mm (range, 0.6 to 3.60 mm) and 0.92 +/- 0.15 mm (range, 0.6 to 1.2 mm) in the control group (P < 0.001). The arterial blood flow was significantly higher in patients with hemorrhoids than in the control group (mean 33.9 vs. 11.9 cm/second, P < 0.01). Our findings demonstrate that increased caliber and arterial blood flow of the terminal branches of the SRA are correlated with the appearance of hemorrhoids. We suggest that the hypervascularization of the anorectum contributes to the growth of hemorrhoids rather than being a consequence of hemorrhoids. Transperineal color Doppler ultrasound (CDUS) is an appropriate method to assess these findings in patients with hemorrhoids.

Constipation of anorectal outlet obstruction: pathophysiology, evaluation and management

Constipation is a subjective symptom of various pathological conditions. Incidence of constipation fluctuates from 2 to 30% in the general population. Approximately 50% of constipated patients referred to tertiary care centers have obstructed defecation constipation. Constipation of obstructed defecation may be due to mechanical causes or functional disorders of the anorectal region. Mechanical causes are related to morphological abnormalities of the anorectum (megarectum, rectal prolapse, rectocele, enterocele, neoplasms, stenosis). Functional disorders are associated with neurological disorders and dysfunction of the pelvic floor muscles or anorectal muscles (anismus, descending perineum syndrome, Hirschsprung's disease). However, this type of constipation should be differentiated by colonic slow transit constipation which, if coexists, should be managed to a second time. Assessment of patients with severe constipation includes a good history, physical examination and specialized investigations (colonic transit time, anorectal manometry, rectal balloon expulsion test, defecography, electromyography), which contribute to the diagnosis and the differential diagnosis of the cause of the obstructed defecation. Thereby, constipated patients can be given appropriate treatment for their problem, which may be conservative (bulk agents, high-fiber diet or laxatives), biofeedback training or surgery.

Anorectal physiology in relation to clinical subgroups of patients with severe constipation

OBJECTIVE

The aim of this study was to evaluate anorectal physiology in relation to clinically defined subgroups of patients with idiopathic constipation and to analyse relationships between anorectal physiology and rectal evacuation.

SUBJECTS AND METHODS

One hundred consecutive patients with idiopathic constipation were clinically categorized as slow transit (n=19), outlet obstruction (n=52) and a group with mixed symptoms (n=29). They were examined by recording anal pressures and also rectal volumes in response to stepwise increases in rectal pressure (5-60 cm H2O). The manovolumetric results were compared with 28 sex and aged matched controls. Rectal evacuation was measured by computer-based image analysis of rectal emptying rate in defaecography.

RESULTS

The rectal pressure thresholds for filling, urge and pain did not differ between the groups but there were proportionally more patients in the slow transit and mixed group with thresholds for filling exceeding 25 cm H2O (P=0.04). In total, 18% of patients had impaired sensitivity which was associated with long duration of symptoms (P < 0.05). Patients with grossly impaired rectal sensitivity (filling threshold > 40 cm H2O) had impaired rectal evacuation (P < 0.05). The rectal compliance was increased in the slow transit and mixed group (P < 0.01-0.05) in the pressure interval 5-15 cm H2O. Anal resting and squeeze pressures did not differ between the groups although 7/19 in the slow transit group had values around the lower limit of controls. Slow wave frequency was lower in all patient groups (P < 0.001 vs. controls). Rectal evacuation was not related to sphincter function or to rectal compliance.

CONCLUSIONS

Clinical categorization of constipated patients defines groups where altered anorectal physiology is not uncommon. Constipation with symptoms of infrequent defaecation may be associated with impaired rectal sensitivity and increased rectal compliance whereas outlet obstruction symptoms are not clearly related to changes in anorectal physiology.

Internal sphincterotomy with hemorrhoidectomy does not relieve pain: a prospective, randomized study

PURPOSE

Pain after hemorrhoidectomy is universal. Several attempts have been made to reduce or alleviate the pain after excisional hemorrhoidectomy. The origin of pain is undetermined. Current theories propose that the pain is mediated through the internal sphincter. This prospective, randomized study was performed to assess the degree of discomfort in patients with and without a sphincterotomy when performing a closed hemorrhoidectomy.

METHODS

Between December 1999 and September 2001, 42 patients (22 males), median age 52 (range, 30-80) years, who underwent excisional hemorrhoidectomy were randomly chosen to have an internal sphincterotomy in the base of the left lateral wound.

RESULTS

Thirty-nine patients were available for the study. Parameters elicited in the study were pain, postoperative bleeding, urinary retention, impairment of continence by day and by night, and day the patient returned to work. There was no statistical difference in the postoperative pain in each of the two categories at four hours after surgery, after the first bowel movement, or four days after surgery.

CONCLUSIONS

Results showed no difference in the perception of pain after hemorrhoidectomy in patients who had an internal sphincterotomy compared with those who did not. Both groups were equally likely to have difficulty with control of gas and soiling.

Quality of life of patients after surgical treatment of anal fistula; the role of anal manometry

OBJECTIVE

This study was undertaken to assess the quality of life of patients after surgical treatment of anal fistula and to investigate whether anal manometry (AM) can guide the choice of the proper surgical intervention in these patients in order to protect the sphincter mechanism.

PATIENTS AND METHODS

One hundred patients with anal fistula (AF) were studied prospectively (78 men; mean age 45 years; range 11-78). Cleveland Incontinence Score (CIS) was record pre-operatively and 1 and 3 months postoperatively for each patient in order to specify their quality of life (QOL) before and after the surgical treatment. Also, anal manometry (AM) was performed pre-operatively and 1 month postoperatively. The pre-operative anal pressures and the type of fistula determined the kind of the surgical treatment. 55 patients had an intersphincteric fistula, 42 trans-sphincteric and 3 suprasphincteric. 65 patients underwent laying open of the fistulous track, 7 fistulectomy and 28 were treated by seton fistulotomy.

RESULTS

Three patients had defective gas control and 6 reported some degree of soiling. 3 patients developed recurrent fistula. CIS was significantly impaired (P=0.02) at the first postoperative month in these patients who were treated for trans-sphincteric fistula by fistulotomy; AM revealed significant decrease of anal pressures in these patients (resting and squeeze; P=0.007 and 0.0001 respectively); CIS and AM in the remaining cases revealed no significant deterioration of QOL and fall of anal pressures respectively. CIS was normal in the vast majority of patients at 3-months postoperatively.

CONCLUSIONS

QOL of patients after surgical treatment of AF is unalterable on the understanding that the AF is simple and the treatment is not associated by incontinence or recurrence. Pre-operative AM is important regarding the choice of the proper surgical procedure.

Pilot study of subtotal colectomy with antiperistaltic cecoproctostomy for the treatment of chronic slow-transit constipation

PURPOSE

Functional results of total colectomy with ileorectal anastomosis for the treatment of chronic constipation caused by colonic inertia are often considered unsatisfactory because of the frequency of postoperative diarrhea and the high rate of postoperative small-bowel obstruction. Patients affected by severe colonic inertia underwent a subtotal colectomy with a novel antiperistaltic cecorectal anastomosis. The aim of the study was to assess the functional results after preservation of the cecorectal junction.

METHODS

Eight females affected by isolated colonic inertia and two females with both paradoxical puborectalis contraction and colonic inertia, of a median age of 40 years, underwent subtotal colectomy with antiperistaltic cecorectal anastomosis. Before antiperistaltic cecorectal anastomosis all ten patients were laxative-dependant, with a mean bowel frequency of ten days; eight of them (80 percent) had distention, seven (70 percent) bloating, and three (30 percent) abdominal pain.

RESULTS

There was no mortality or major postoperative morbidity. One month after antiperistaltic cecorectal anastomosis, bowel frequency was a mean of 2.2 (range, 1-4) per day, with a semiliquid stool consistency. After one year, bowel frequency was a mean of 1.3 (range, 0.5-3) per day, with a solid stool consistency; the same results were recorded at last follow-up. Although no patients used antidiarrheal medicine, laxatives continued to be used by both patients with paradoxical puborectalis contraction. All ten (100 percent) of the patients reported a good or improved quality of life.

CONCLUSION

This preliminary experience seems to show that antiperistaltic cecorectal anastomosis is safe and effective for patients with colonic inertia. It results in prompt and prolonged relief from constipation for patients with isolated colonic inertia.

Anal pressure waves in patients with irritable bowel syndrome

PURPOSE

Many data suggest in irritable bowel syndrome a generalized smooth-muscle disorder, but data are scant concerning anal waves in patients with irritable bowel syndrome. The aim of the present study was first to propose a new method of anal pressure-wave analysis and second to apply this method to patients with irritable bowel syndrome.

METHODS

Spectral analysis was used in 20 healthy controls and 60 patients with irritable bowel syndrome to investigate anal pressure waves at rest during a standard anorectal test and during a maintained 12-ml anal distention.

RESULTS

Adaptation of the anal canal to maintained distention was similar in the two groups of subjects. Using a cluster analysis, three groups of anal waves were defined (in cycles per minute): ultra slow waves (0.9-3.3), slow waves (3.8-16.4), and simple waves (16.9-23). In the resting state only simple waves were found less prevalent in patients with irritable bowel syndrome. During maintained distention, ultra slow waves increase in both groups, but slow waves increase in patients with irritable bowel syndrome and simple waves decrease in controls.

CONCLUSIONS

Characterization of anal pressure waves is a simple procedure that is easy to perform in outpatients. Anal pressure waves of patients with irritable bowel syndrome have altered organization and respond differently to distention as compared with controls.

Local thermal stimulation relaxes hypertonic anal sphincter: evidence of somatoanal reflex

PURPOSE

Although it is generally believed that warm perineal baths reduce pain resulting from anal fissure, complicated hemorrhoids, or anal surgery, the exact mechanisms remain unclear. Because hypertonicity of the internal anal sphincter contributes to increasing pain in these conditions, it has been postulated that warm perineal baths could help to relax the anal sphincter, hence reducing pain. It is our purpose to demonstrate response of the anal sphincter to local thermal stimulation via a somatoanal reflex.

METHODS

Continuous anorectal manometry tracings were obtained from 15 healthy volunteers, 22 patients with hemorrhoid, and 20 patients with anal fissure. Local thermal stimulation was achieved by applying a heat pad on the right infragluteal region (local area), and subsequently on the right first interphalangeal region (control area).

RESULTS

Obvious response to local thermal stimulation was shown by 13.3 percent of volunteers, 36.4 percent of patients with hemorrhoid, and 60 percent of patients with fissure. Heat-sensitive patients who responded to local thermal stimulation were divided to two groups, those with ultraslow waves and those without ultraslow waves. In patients with ultraslow waves, the amplitude of ultraslow waves decreased significantly after local thermal stimulation, with amplitude before local thermal stimulation, (mean +/- standard deviation) 66.2 +/- 30.6 mmHg, and during local thermal stimulation, 43.2 +/- 22.3 mmHg, respectively, P = 0.003. By contrast, in patients without ultraslow waves, the tonic pressure measured before local thermal stimulation and during local thermal stimulation was 74.2 +/- 23.5 and 60.5 +/- 18.5 mmHg, respectively, P = 0.001. The response began at approximately three minutes after local thermal stimulation when the skin temperature was 42.1 +/- 0.3 degrees C. No anal response was observed when the heat pad was applied to the control area. The maximum resting pressure of the heat-sensitive patients was significantly higher than that of the nonresponding patients (97.3 +/- 0.1 vs. 76.9 +/- 23.3 mmHg; P = 0.012).

CONCLUSIONS

Local thermal stimulation evokes relaxation of the hypertonic internal anal sphincter through a somatoanal reflex, thus providing an easy and feasible method of clinical application.

Manometric tests of anorectal function in healthy adults

OBJECTIVE

Although tests of anorectal function are useful in the assessment of defecation disorders, there is inadequate and inconsistent information regarding normative data. Also, there are discrepancies in manometric techniques and data interpretation. Our aim was to perform a comprehensive evaluation of anorectal function in healthy adults.

METHODS

We used a 6-mm diameter probe containing six radially arrayed microtransducers, and a 4-cm-long latex balloon for performing anorectal manometry in 45 healthy subjects who were controlled for gender and age. Sequentially, subjects were asked to squeeze, bear down, or blow up a party balloon. Subsequently, rectal sensation, rectal compliance, and rectoanal reflexes were assessed simultaneously by performing intermittent phasic balloon distentions. Additionally, balloon defecation, pudendal nerve latency, and saline continence tests were performed.

RESULTS

In men, the anal sphincter was longer (p < 0.05) and squeeze sphincter pressure and squeeze duration were higher (p < 0.01), but resting sphincter pressure was similar to that in women. When bearing down, although not significant, the defecation index was higher in men. Distinct thresholds for rectal sensation were identified but there was no gender difference. Likewise, rectal compliance and balloon expulsion time were similar. However, during saline infusion, the onset of first leak and total volume retained were higher (p < 0.001) and pudendal nerve latency was shorter (p < 0.05) in men. Overall, parity or age did not influence anorectal function.

CONCLUSIONS

This study represents the most comprehensive age- and gender-controlled assessment of anorectal function using solid state technology. Gender influences some parameters of anorectal function. Our results could serve as a valuable resource of normative data.

Internal anal sphincter: advances and insights

The internal anal sphincter, the smooth muscle component of the anal sphincter complex, has an ambiguous role in maintaining anal continence. Despite its significant contribution to resting anal canal pressures, even total division of the internal anal sphincter in surgery for anal fistulas may fail to compromise continence in otherwise healthy subjects. However, recently reported abnormalities of the innervation and reflex response of the internal anal sphincter in patients with fecal incontinence indicate its significance in maintaining continence. The advent of sphincter-saving surgery and restorative proctocolectomy has re-emphasized the major contribution of the internal anal sphincter to resting pressure and its significance in preventing fecal leakage. The variable effect of rectal excision on rectoanal inhibitory reflex has led to a reappraisal of the significance of this reflex in discrimination of rectal contents and its impact on anal continence. Electromyographic, manometric, and ultrasonographic evaluation of the internal anal sphincter has provided new insights into its pathophysiology. This article reviews advances in our understanding of internal anal sphincter physiology in health and disease.

Patterns of anismus and the relation to biofeedback therapy

PURPOSE

A study was undertaken to assess physiologic characteristics and clinical significance of anismus. Specifically, we sought to assess patterns of anismus and the relation of these findings to the success of therapy.

METHODS

Sixty-eight patients were found to have anismus based on history and diagnostic criteria including anismus by defecography and at least one of three additional tests: anorectal manometry, electromyography, or colonic transit time study. Interpretation of defecography was based on the consensus of at least three of four observers. Anal canal hypertonia (n = 32) was defined when mean and maximum resting pressures were at least 1 standard deviation higher than those in 63 controls. There were two distinct defecographic patterns of anismus: Type A (n = 26), a flattened anorectal angle without definitive puborectalis indentation but a closed anal canal; Type B (n = 42), a clear puborectalis indentation, narrow anorectal angle, and closed anal canal. Outcomes of 57 patients who had electromyographybased biofeedback therapy were reported as either improved or unimproved at a mean follow-up of 23.7 (range, 6-62) months. These two types of anismus were compared with biofeedback outcome to assess clinical relevance.

RESULTS

Patients with Type A anismus showed greater perineal descent at rest (mean, 5.1 vs. 3.5 cm; P < 0.01), greater dynamic descent between rest and evacuation (mean, 2.7 vs. 1.4 cm; P < 0.01), greater difference of anorectal angle between rest and evacuation (mean, 14.6 vs. -3.1 degrees; P < 0.001), higher mean resting pressure (mean, 77.1 vs. 62.8 mmHg; P < 0.05), lower mean squeeze pressure (58.8 vs. 80.7 mmHg; P < 0.05), and a higher incidence of anal canal hypertonia (69.2 vs. 33.3 percent; P < 0.01) than did patients with Type B anismus. Only 25 percent of patients who had Type A anismus with anal canal hypertonia were improved by biofeedback therapy. Conversely, 86 percent of patients with Type B anismus without anal canal hypertonia were successfully treated with biofeedback (P < 0.001; Fisher's exact test).

CONCLUSIONS

These two distinct physiologic patterns of anismus correlate with the success of biofeedback treatment. Therefore, knowledge of these patterns may help direct therapy.

Physiology of ileal pouch-anal anastomosis. Current concepts

PURPOSE

Increasing experience with ileal pouch-anal anastomosis (IPAA) associated with increasing knowledge about anorectal physiology has lead to a large number of publications. The purpose of this review is to evaluate the current understanding of fecal continence as revealed by the evolution of the ileoanal procedure.

METHODS

Review of the literature covering the most important physiologic parameters involved in fecal continence was undertaken.

RESULTS

Rectoanal inhibitory reflex is probably absent after IPAA but is preserved when distal anorectal mucosa is spared. Anal resting pressure decreases but is less affected when the internal anal sphincter is less traumatized. Squeeze pressure is not importantly affected, and the importance of reservoir function as a determinant of stool frequency is emphasized. IPAA does not affect the coordination between pouch and anal canal motility in the majority of cases. Normal continence is preserved, even during the night, by preserving a gradient of pressure between the pouch and anal canal.

CONCLUSIONS

Physiologic concepts are well established, but controversies about the continence mechanism related to IPAA remain. The IPAA procedure has allowed discrimination of details about the function of multiple structures involved in fecal continence.

The position of the patient does not adversely influence the results of the most clinically important measurements of anorectal function

Anorectal physiological measurements were carried out in three groups of patients: Controls (n = 11), slow transit constipation (n = 21) and neuropathic faecal incontinence (n = 14) to examine whether the position of the patient influenced the result of tests of anorectal function. Measurements were made in both the conventional left lateral and the seated position. No significant differences were observed in the pressures within the anal canal at 2 cm from the anal verge, the usual site of maximum resting and maximum squeeze pressures, although, at 4 cm pressures were significantly different in the two positions. With all other tests including rectal compliance, anorectal inhibitory reflex and rectal sensation there was no significant difference due to position in any of the three clinical groups. We conclude that the left lateral position is generally satisfactory for measurement of the most clinically important aspects of anorectal function.

Computer-generated profiles of the anal canal in patients with anal fissure

PURPOSE

The pathophysiology of anal fissure remains poorly understood. This study examines manometric findings in patients with anal fissure with use of a computer-assisted system, which helps to standardize manometric performance as well as generating longitudinal and cross-sectional profiles of the anal canal.

METHODS

Water-perfused, eight-channel, computer-assisted manometry was performed on 12 patients with chronic anal fissure and compared with 12 age-matched and sex-matched controls.

RESULTS

Mean maximum average resting pressure (MARP) was 120.5 mmHg in patients and 82.6 mmHg in controls (P = 0.0005). Pain was felt during manometry in six patients. In these patients, MARP was 123.2 mmHg, and, in the other six patients, MARP was 117.8 mmHg. Sphincter length was 4.72 cm, and the high pressure zone or that part of the sphincter with pressure more than 50 percent of MARP) was 2.78 cm in length. The high pressure zone/sphincter length ratio was 58 percent compared with 48 percent in controls. Longitudinal profile was bell shaped. Elevated pressures were not confined to the site of the fissure. Cross-sectional analysis showed higher anterior pressures in the distal sphincter. Ultraslow waves were seen in as many as 91 percent of patients and 73 percent of controls. However, ultraslow wave amplitude was 31 mmHg in patients and 15 mmHg in controls (P = 0.03). The rectoanal reflex was normal; overshoot was not seen.

CONCLUSIONS

The primary abnormality in fissure is persistent hypertonia affecting the entire internal sphincter, unrelated to pain. Cross-sectional pressure profiles may explain the predilection of fissures to occur in the posterior midline; other factors must prevent chronic fissures from healing.

Haemorrhoids: pathology, pathophysiology and aetiology

Haemorrhoidal disease is the consequence of distal displacement of the anal cushions, which are normal structures with an important role in continence. The causes of haemorrhoidal disease are unknown; constipation and abnormal bowel habit are commonly blamed despite largely contrary evidence. The most consistently demonstrated physiological abnormality is an increased maximum resting anal pressure. Most evidence points to this being a secondary phenomenon rather than the cause of haemorrhoidal disease. Among the many unexplored areas are the function of the longitudinal muscle in relation to haemorrhoidal disease, the description and pharmacological responsiveness of the anal subepithelial muscle, and the clinical role of specific pharmacological agents that might reverse some of the observed physiological changes.

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.

Internal anal sphincter activity after restorative proctocolectomy for ulcerative colitis: a study using continuous ambulatory manometry

PURPOSE

The aim of this study was to further investigate continuous ambulatory anal manometry which has recently been introduced as a method for studying anorectal activity in ambulant patients, thereby avoiding many of the potential drawbacks of static techniques.

METHOD

In this study continuous ambulatory manometry was used to assess the activity of the internal anal sphincter in patients who had undergone restorative proctocolectomy, and, in particular, to compare patients who had undergone conventional mucosal proctectomy with sutured endoanal, ileoanal anastomosis with patients who had undergone restorative proctocolectomy with preservation of the entire anal canal by means of stapled, end-to-end, ileoanal anastomosis without mucosectomy.

RESULTS

Evidence of basal internal sphincter activity was found in only 38 percent of patients after mucosal proctectomy with sutured endoanal anastomosis, whereas all patients after restorative proctocolectomy with stapled end-to-end anastomosis and all control individuals showed such activity of the internal sphincter. Similarly, the number of sampling episodes seen in patients after mucosal proctectomy with endoanal anastomosis was significantly less (median, 0.0/hours (0-30/hours)) than the number of sampling episodes observed in patients after end-to-end anastomosis (median, 4.5/hours (1-48/hours)) or in control individuals (median, 5.6/hours (0-31/hours)) (P < 0.001).

CONCLUSIONS

These results suggest that the internal anal sphincter is damaged in the course of mucosal proctectomy and endoanal anastomosis. In contrast, after restorative proctocolectomy with stapled, end-to-end anastomosis normal function of the internal sphincter is preserved.

Ultra slow wave pressure variations in the anal canal before and after lateral internal sphincterotomy

Ultra slow waves (USW's) in the anal canal are discrete pressure fluctuations with a low frequency (1-2/minute) and high amplitude (> or = 10% above or below baseline resting pressure). To investigate the nature of these USW's, anorectal manometry was performed in 20 control subjects as well as in 58 patients presenting with anal fissure or symptomatic hemorrhoids, before and 2 weeks after lateral internal sphincterotomy. USW's could be demonstrated in two control subjects and in 29 patients. The median value of maximum anal resting pressure (MARP) in the two control subjects with USW's was significantly higher than the median MARP in the 18 control subjects without USW's (181.5 vs. 92 cm H2O, p < 0.001, two-tailed Mann-Whitney test). The same difference was found between MARP in patients with and without USW's (158 vs. 138 cm H2O, p < 0.05, two-tailed Mann-Whitney test). All patients were treated by means of lateral internal sphincterotomy (LIS). Two weeks after this procedure USW's had disappeared in half of the patients. The MARP in these patients was reduced to a level found in control subjects without USW's. This pressure reduction was significantly greater than in patients with persistent USW's (40% vs. 15%, p < 0.02, two-tailed Mann-Whitney test). Because USW's are associated with high MARP and disappear when such a high anal canal resting pressure is reduced by LIS to a level found in control subjects without USW's, it can be concluded that USW's are the manifestation of increased activity of the internal anal sphincter.

Dynamic anal manometry: physiological variations and pathophysiological findings in fecal incontinence

A recently developed technique for dynamic anal manometry was used to study 40 healthy volunteers and 23 patients with fecal incontinence. Seven parameters of anal function were measured. Intraindividual variation of the parameters was studied in 5 females and 5 males. The results of dynamic anal manometry were compared with standard pull-through static anal manometry and correlated well. During opening of the anal sphincter at rest, compliance increased with increasing distension. Males had higher maximal closing pressures during squeeze and lower anal compliance during squeeze than females. There was no sex differences of the sphincter measurements at rest. Age had little effect, and gender had no effect on the measurements. With standard anal manometry, 6 of 23 patients with fecal incontinence both had maximal resting pressure and maximal squeeze pressure within the normal range. When dynamic anal manometry was used, all 23 patients showed one or more abnormal values. The method of dynamic anal manometry provides an opportunity for a more thorough assessment of anal sphincter function than previous manometric methods.

Anal fissure: correlation between symptoms and manometry before and after surgery

The study compared symptoms and manometric results in 76 patients (42 men and 34 women; median age: 45 years) before and at long-term follow-up (median time: 54 months) after fissurectomy with posterior midline sphincterotomy for anal fissure. The fissure healed in all cases. Sporadic loss of continence for flatus or for liquid stool occurred in 21 patients (27.6%) and soiling was present in 7 other patients (9.2%). Preoperative maximum resting anal pressure was significantly greater in the study group compared with 40 control subjects (p less than 0.001). Postoperative resting anal pressure fell significantly (p less than 0.001) and remained low on long-term assessment. Postoperative maximal squeeze pressure remained unchanged. No correlation could be found between preoperative and postoperative clinical symptoms (including continence) and anorectal manometry.

The role and technique of ambulatory anal manometry

Static anal manometry has proved itself a reliable, reproducible and objective assessment of sphincter function in the investigation of disorders of defecation and continence. Despite this, it gives only very limited information on sphincter function due to the unphysiological nature of its measurement. Technical advances, particularly in digital data storage, have made the recording of anal pressure in a normal environment for prolonged periods of time possible. This offers an improved understanding both of anal activity and the interaction of rectal and anal function in normal and pathological states. In normal subjects anal function during a number of normal physiological events such as micturition, passage of flatus and sleep have been investigated. The sampling reflex has been further defined. Abnormalities of the sampling reflex, rectal activity and slow wave activity in the anal sphincter have been demonstrated in a number of pathological conditions of the anorectum and in the states of incontinence or constipation. Effective ambulatory anal manometry remains in its infancy. With continuing advances it offers exciting possibilities in defining normal or abnormal activity of the anorectum and in the investigation of patients with disorders of defecation and continence.

The internal anal sphincter: mechanisms of control and its role in maintaining anal continence

The human IAS has particular structural and functional characteristics. This smooth muscle constantly generates rhythmic electrical slow waves, but no action potentials. The slow waves are linked to calcium fluxes and both are essential for mechanical activity, i.e. the ASPW. The IAS is pharmacologically characterized by the presence of alpha excitatory and beta inhibitory adrenergic receptors. Cholinergic drugs have an indirect effect through the release of an inhibitory neurotransmitter, very probably VIP, from NANC nerves. The myogenic activity of the IAS is enhanced by its extrinsic sympathetic innervation. Thus, at rest, the IAS is in a state of partial tetanus and contributes approximately 55% of the MABP. Because the IAS ring cannot be completely closed, the anal mucosa and the haemorrhoidal plexuses fill the gap. By compressing these tissues, the IAS perfectly closes the anal canal to retain not only solids but also fluid stool and gas. Acute rectal distension and rectal activity, mainly through intramural pathways, induce reflex IAS relaxation, permitting the rectal contents to be sampled by receptors in the upper anal canal while continence is temporarily maintained by EAS activity and by expansion of the haemorrhoidal cushions. There is a correlation between the volume of rectal distension and the parameters of IAS relaxation. At maximal IAS relaxation, ASPW are absent, indicating the completeness of the inhibition. Although this RAIR is not essential for defecation, insufficient relaxation may be implicated in constipation. Hyperactivity of the IAS resulting in a high MABP and AUSPW has been considered both as a cause and as an effect in haemorrhoids and anal fissure. Continence for fluids and gas is impaired if IAS activity is decreased (i.e. a low MABP), either by direct trauma or by damage of its sympathetic innervation. Severe faecal incontinence will develop when the contractility of both the IAS and the EAS is affected.

High and intermediate imperforate anus: results after surgical correction with special respect to internal sphincter function

Embryologically a fistula in an anorectal malformation can be regarded as an ectopic anus. Since 1984 the so-called fistula has been saved and used as the new anal canal in the surgical reconstruction of 48 patients with high or intermediate imperforate anus. A positive rectoanal inhibitory reflex indicating internal sphincter function was recorded in 32 of 43 patients investigated with anorectal manometry. These patients showed significantly better anal continence. It is concluded that there is an internal sphincter "anlage" in the fistulous connection from the bowel to the urogenital tract. Internal sphincter function can be obtained in the majority of the patients, which seems advantageous for their anal function.

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.

Human anal motility while fasting, after feeding, and during sleep

The aim of this study was to determine whether the human anal sphincter responds dynamically to changing physiological states. In 19 healthy human subjects, intraluminal anal canal pressure was measured with a 5-cm perfused sleeve sensor during the day while fasting (3 hours) and after feeding (3 hours) and at night during sleep (8 hours). Daytime mean anal canal pressures (+/- SEM) while fasting (50 +/- 3 mm Hg) were similar to those after feeding (49 +/- 3 mm Hg) and to those at night during sleep (49 +/- 3 mm Hg). Marked minute-to-minute variations in mean pressure occurred in all three periods, however, as did large phasic increases and decreases in pressure (greater than 20 mm Hg) and small phasic changes in pressure less than 20 mm Hg (anal slow waves). The minute-to-minute variations in mean pressure were greater during the awake fed state (4 +/- 1 mm Hg/min) than at night during sleep (2 +/- 1 mm Hg/min; P less than 0.03), as were the number of large phasic waves per minute (increases in pressure: awake, fed = 0.5 +/- 1 waves/min, night = 0.3 +/- 0.1 waves/min, P less than 0.05; decreases in pressure: awake, fed = 0.4 +/- 0.1 waves/min, night = 0.2 +/- 0.1 waves/min, P less than 0.05). Anal small waves had a similar frequency of about 17 waves/min in all three states. In conclusion, the anal sphincter maintains a continuous pressure barrier to rectal outflow both during the day and at night during sleep. However, marked minute-to-minute variations in mean pressure and large phasic increases and decreases in pressure do occur. Both are fewer at night during sleep.

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.

Anorectal and pelvic floor disorders: putting physiology into practice

The pathophysiology of the pelvic floor syndromes is complex and confusing. Childbirth is the only aetiological agent to have been clearly identified, but its role is not universal. Learned or psychogenic pelvic floor incoordination is likely to play a part. The conditions are so intertwined that an increasingly comprehensive battery of tests has become necessary to try to unravel the component disorders; anorectal physiology testing has therefore assumed an important position in the evaluation of these patients. It is only by careful application of physiological studies in clinical practice that further advances can be made. The investigations currently available can contribute significantly to determining the optimum management of these difficult patients. Surgical indications continue to be refined. The results of careful clinical and laboratory follow-up studies have led to changes in practice. The pelvic floor syndromes have only recently been defined; there is still much work to be done.

Prolonged ambulant assessment of anorectal function in patients with prolapsing hemorrhoids

Six patients with prolapsing hemorrhoids and 12 control subjects had assessment of anorectal pressure and external sphincter electromyography performed over a prolonged period under ambulant conditions. Patients with prolapsing hemorrhoids demonstrated greater degrees of sampling responses, 12.9 +/- 1.9/hour, vs. 7.4 +/- 2.0/hour (mean +/- SEM) in controls (P less than .05). Ultraslow wave and giant ultraslow wave activity were seen frequently in the patient group occupying more than 30 percent of recording. The external sphincter demonstrated much greater electrical activity (spike potentials) in patients with hemorrhoids than in controls both by day, 24.9 +/- 11.0/10 min vs. 12.8 +/- 3.2/10 min (P less than .02), and by night, 7.4 +/- 2.6 min vs. 1.6 +/- 1.3/10 min (P less than .03). Sleep electrical activity in the presence of hemorrhoids did not differ significantly from that of controls during waking, 7.4 +/- 2.6/10 min vs. 12.8 +/- 3.2/10 min (P less than .1). No difference in phasic and periodic rectal motor activity was noted between patient and control groups. This demonstrates the application of prolonged assessment of anorectal motility and external sphincter activity in a patient group. Abnormalities previously documented in patients with hemorrhoids using conventional manometric tests were confirmed. In addition, evidence of increased external sphincter function during waking and sleep may have implications in the pathophysiology of this disorder.

Effects of aging on the anorectal sphincters and their innervation

The effects of aging on the pelvic floor musculature and its innervation are described in 102 women and 19 men without colorectal or pelvic floor disease. In the women, a reduction in anorectal "squeeze" pressure was found in the fifth decade, but the resting anal pressure remained unchanged. This reduction in squeeze anal pressure was accompanied by an increase in the mean pudendal nerve terminal motor latency, indicating damage to this nerve, and increased perineal descent in the resting and straining positions. The fiber density, recorded by single fiber electromyography in the external anal sphincter muscle, a muscle innervated by the pudendal nerves, was increased in the sixth decade, indicating the later development of compensatory reinnervation in this muscle. The interrelation of aging, menopausal effects, and parity in these changes is difficult to define from currently available data, but the authors suggest, from other evidence, that menopausal effects may be relevant.

Clinical results of colectomy for severe constipation

Subtotal colectomy has been performed in 40 patients with severe constipation. Only one patient was male. Five patients (13 per cent) had a history of a serious psychiatric disorder. Twenty-six patients (65 per cent) could not expel a 100-ml air-filled balloon and 19 patients (48 per cent) had electromyographic evidence of abnormal puborectalis contraction during attempted defaecation before operation. Median preoperative passage of 50 radio-opaque markers over 5 days was 16 per cent. Sixteen patients had had a previous anorectal myectomy to exclude Hirschsprung's disease. Initial resections were subtotal colectomy and ileorectal anastomosis (n = 34), caecorectal (n = 5) or ileosigmoid (n = 1) anastomosis. Secondary operations included restorative proctocolectomy and ileal pouch-anal anastomosis (n = 6) and six patients eventually had an ileostomy. Median bowel frequency per week significantly increased after operation (0.3 (range 0-1) preoperatively to 21 (range 2-70) postoperatively, P less than 0.005), the percentage of patients with abdominal pain fell after operation from 93 to 39 per cent but symptoms of abdominal distension remained the same (86 per cent preoperatively and 82 per cent postoperatively).

Spontaneous anorectal pressure activity. Evidence of internal anal sphincter contractions in response to rectal pressure waves

To characterize spontaneous anorectal pressure activity and a possible relation between the activity in the rectum and the anal canal, 11 healthy female volunteers were investigated. Resting activities were obtained during 1-h recordings with a multi-channel perfused catheter measuring the pressure 1, 2, 3, 7, and 8 cm from the anal verge. In five subjects sequences of rhythmic rectal pressure waves with amplitudes exceeding the maximal anal resting pressure coincided with a similar internal anal sphincter activity, preventing rectal pressure from exceeding the anal pressure at any point. The mean frequency was 5 x min-1 (range, 3-6 x min-1). This may well be a reflex mechanism by which the internal anal sphincter prevents incontinence in the resting state. Low-frequency pressure waves, not previously described, were detected in four women. These pressure waves were attributed to the internal anal sphincter and were named ultra-slow waves type II. The mean frequency and amplitude were 0.16 x min-1 (range, 0.15-0.17 x min-1) and 24 cm H2O (range, 11-41 cm H2O), respectively. The function of these pressure waves is unknown.

Air-filled microballoon manometry for use in anorectal physiology

Manometry is fundamental to anorectal physiology but the water-filled manometric systems commonly used have several disadvantages. To investigate the 'new' air-filled microballoon system, we compared it with a standard water-filled equivalent by measuring sphincter length, maximum resting pressure (MRP) and maximum voluntary contraction pressure (MVC) in 44 patients using the station pull-through technique. A good correlation was found for all three parameters (Spearman correlation coefficient rs: sphincter length = 0.86, MRP = 0.86 and MVC = 0.94, P less than 0.001). Repeat studies in 15 patients showed excellent reproducibility (rs: sphincter length = 0.97, MRP = 0.96 and MVC = 0.97, P less than 0.001). Air-filled microballoon manometry gives results similar to a water-filled microballoon system and has many advantages.