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

Understanding of Constipation Symptoms and the Diagnosis and Management of Constipation in Chinese Physicians

Background and Aims

Although a range of guidelines for the diagnosis and treatment of chronic constipation has been carried out, there was very little information about the understanding on constipation. The aim of the present study was to estimate the understanding of constipation symptoms and the diagnosis and management of constipation by clinical physicians in China.

Methods

Participants were physicians and researchers in the field of gastroenterology in China who were scheduled to attend the National Conference on gastrointestinal motility(Constipation). Based on the recommendation of the Rome Foundation Board, the self-reported questionnaire was constructed.

Findings

Although most of the opinions on symptoms of constipation were consistent, there were still some differences. Opinions on the Bristol stool form during constipation were discordant, 34% of the doctors thought that it was type 1 and type 2, while 46%of the doctors suggested that type 3 should also be considered constipation. There was no significant difference between them(P = 0.05); We investigated the interpretation on the duration of defecation prolonged, 27% of the doctors suggested it should be longer than 10 minutes, 22% of the doctors suggested it should be longer than 20 minutes, and other 22% of the doctors suggested it should be time of defecation became longer compared to previously bowel habits, there was no significant difference among them(P = 0.38).Only 36% of the doctors thought that psychotherapy was most important in the treatment of severe constipation, while 37% of the doctors thought that medication treatment was most important in the treatment of severe constipation, there was no significant difference between them(P = 0.895).

Conclusion

We were able to obtain valuable information about current views on symptoms of constipation and the diagnosis and treatment of constipation among Chinese doctors. Although most of the opinions were consistent there were still some differences. This study indicated that in practice in China there was a need for further study on the role of constipation symptoms and there may also be a need for better establishment of consensus guidelines for constipation.

Diagnostic accuracy study of anorectal manometry for diagnosis of dyssynergic defecation

OBJECTIVE

The diagnostic accuracy of anorectal manometry (AM), which is necessary to diagnose functional defecatory disorders (FDD), is unknown. Using blinded analysis and standardised reporting of diagnostic accuracy, we evaluated whether AM could discriminate between asymptomatic controls and patients with functional constipation (FC).

DESIGN

Derived line plots of anorectal pressure profiles during simulated defecation were independently analysed in random order by three expert observers blinded to health status in 85 women with FC and 85 age-matched asymptomatic healthy volunteers (HV). Using accepted criteria, these pressure profiles were characterised as normal (ie, increased rectal pressure coordinated with anal relaxation) or types I-IV dyssynergia. Interobserver agreement and diagnostic accuracy were determined.

RESULTS

Blinded consensus-based assessment disclosed a normal pattern in 16/170 (9%) of all participants and only 11/85 (13%) HV. The combined frequency of dyssynergic patterns (I-IV) was very similar in FC (80/85 (94%)) and HV (74/85 (87%)). Type I dyssynergia ('paradoxical' contraction) was less prevalent in FC (17/85 (20%) than in HV (31/85 (36.5%), p=0.03). After statistical correction, only type IV dyssynergia was moderately useful for discriminating between FC (39/85 (46%)) and HV (17/85 (20%)) (p=0.001, positive predictive value=70.0%, positive likelihood ratio=2.3). Interobserver agreement was substantial or moderate for identifying a normal pattern, dyssynergia types I and IV, and FDD, and fair for types II and III.

CONCLUSIONS

While the interpretation of AM patterns is reproducible, nearly 90% of HV have a pattern that is currently regarded as 'abnormal' by AM. Hence, AM is of limited utility for distinguishing between FC and HV.

Manometric assessment of idiopathic megarectum in constipated children

AIM: Chronic constipation is a frequent finding in children. In this age range, the concomitant occurrence of megarectum is not uncommon. However, the definition of megarectum is variable, and a few data exist for Italy. We studied anorectal manometric variables and sensation in a group of constipated children with megarectum defined by radiologic criteria. Data from this group were compared with those obtained in a similar group of children with recurrent abdominal pain.

METHODS: Anorectal testing was carried out in both groups by standard manometric technique and rectal balloon expulsion test.

RESULTS: Megarectum patients displayed discrete abnormalities of anorectal variables and sensation with respect to controls. In particular, the pelvic floor function appeared to be impaired in most patients.

CONCLUSION: Constipated children with megarectum have abnormal anorectal function and sensation. These findings may be helpful for a better understanding of the pathophysiological basis of this condition.

Evaluation of the paradoxical sphincter contraction by a strain/squeeze index in constipated patients

PURPOSE

One finding in patients with constipation is the paradoxical puborectalis contraction, i.e. , activation of the sphincter muscles during straining instead of relaxation. The aims of this study were to evaluate the importance of needle placement in sphincter-electromyography and to evaluate a strain/squeeze index in constipated patients and control subjects.

METHODS

We investigated consecutively 194 constipated patients and 16 control subjects with integrated electromyography during straining and squeezing and calculated a strain/squeeze index. The examination was performed in the puborectalis and in the external anal sphincter muscle through hook-electrodes.

RESULTS

There was a strong correlation between indices in the puborectalis muscle and in the external anal sphincter muscle (r = 0.70-0.80, P < 0.001). Forty-seven patients (24 percent) had a mean index of greater than 50 compared with none in the control group (P = 0.01). Mean overall index in patients was 24 (range, 0-306) vs. 18 (range, 0-45) in controls (P = 0.12). Patients with an index greater than 50 had impaired rectal evacuation (P < 0.001), increased threshold for urge (P < 0.05), and tended to have fewer stools (P = 0.06).

CONCLUSION

Quantification of paradoxical contraction in the puborectalis and external anal sphincter with a strain/squeeze index differentiates patients in whom paradoxical activity may be a cause of constipation. An index above 50 may be of pathologic significance. Correlations between activity in the puborectalis and external anal sphincter muscle were strong which suggests that investigation in one of them is sufficient.

Posterior pelvic floor compartment disorders

Posterior pelvic floor compartment disorders generally refer to functional anorectal disturbances that by definition are symptom-based rather than anatomical defect-based and have a significant impact on quality of life. Symptoms attributed to the posterior compartment are often non-specific and associated with structural, neuromuscular and functional defects giving rise to symptoms of prolapse, pelvic pressure, faecal incontinence, stool trapping and constipation. They may range from mild to incapacitating and occur in varying combinations. While symptoms of constipation and incontinence may conceptually represent the opposing extremes of normal anorectal function, the dynamic interrelationships between the different pathophysiological mechanisms involved in the development of these disorders suggest a more complex explanation. Faecal continence and defecation are dependent on several neurological and anatomical factors that involve coordinated physiological processes, including intestinal transit and absorption, colonic transit, rectal compliance, anorectal sensation and continence mechanism. However, it is well recognized that pelvic floor symptoms originating from one compartment do not imply absent pathology in another compartment. Furthermore, symptoms associated with one disorder (such as constipation related to functional obstructed defecation) can be causative in the sequential development of other pelvic floor disorders, such as a urogenital prolapse syndrome, that may further exacerbate symptoms. In addition, it has been found that treatment that corrects one problem may improve, worsen or even predispose to other symptoms from another compartment. Consequently, while the concept of global pelvic floor dysfunction has emerged, the traditional single speciality referral and evaluation of pelvic floor problems continues to foster potentially segregated management strategies that can overlook the relevance of concomitant symptomatology. The evaluation and treatment of posterior pelvic compartment disorders needs to assume an individualized but multidisciplinary therapeutic approach. Given the variation in surgical approaches described to correct anatomical integrity of posterior pelvic compartment deficits, the consensus on optimal management has yet to be achieved. Therefore, it is critical that outcome measures following surgery are clearly defined. Treatment is to a great extent dictated to by functional severity and the impact that symptoms have on quality of life. Long-term follow-up should ensure that the potential for complications is minimized and satisfactory bowel, bladder and sexual function is maintained.

The puborectalis muscle

The role of the levator ani and puborectalis muscle in preserving continence has been underestimated in the past, due predominantly to technical difficulties to investigate its proper function in healthy subjects, and its dysfunction as in patients with incontinence problems. This has recently been overcome by applying new investigational procedures such as a perineal dynamometer which measures the traction exerted by the levator ani on an intrarectal balloon catheter, or by multi-electrode arrays recording the generation of motor unit action potentials from various parts of the puborectalis muscle sling via intrarectal surface electrodes. Both techniques have the potential to provide new insights into the physiology of defecation and the pathophysiology of incontinence and constipation.

Electromyography of the pelvic floor musculature in the assessment of obstructed defecation symptoms

PURPOSE

The purpose of this study was to use electromyography to examine the behavior of the external sphincter, puborectalis muscle, and pubococcygeus muscle during attempted defecation in patients with symptoms of obstructed defecation and in normal subjects to highlight differences of clinical significance.

METHODS

A total of 35 patients (31 females) aged 20 to 80 (mean, 53.7 +/- 13.3) years with unprepared bowel who had normal colon transit time and obstructed defecation symptoms and 12 voluntary control subjects (7 females) aged 23 to 68 (mean, 48 +/- 11.5) years underwent an electromyography evaluation of the activity of the external sphincter, puborectalis muscle, and pubococcygeus muscle during attempted defecation. The patients were also examined in separate sessions with defecography and anal manometry.

RESULTS

During attempted defecation, puborectalis muscle and external sphincter always reacted in the same manner. When evaluated with pubococcygeus muscle, three main patterns of activity were observed either in patients or in controls: 1) coordinated activation pattern; 2) coordinated inhibition pattern; and 3) uncoordinated or equivocal pattern: activation of pubococcygeus muscle with inhibition of puborectalis muscle/external sphincter, activation followed by inhibition of the three muscles, and activation followed by inhibition of pubococcygeus muscle and no change in the others. We never observed activation of puborectalis muscle/external sphincter concomitant with inhibition of pubococcygeus muscle. The inhibitory coordinated pattern occurred significantly (P = 0.01) more frequently in controls than in patients. These subjects also presented a significantly (P = 0.01) lower frequency of pubococcygeus muscle inhibition.

CONCLUSIONS

Either activation or inhibition appears as a physiological behavior, possibly adopted in different circumstances, of the pelvic floor muscles during attempted defecation. The higher prevalence of coordinated inhibitory patterns in normal subjects and the lower frequency of pubococcygeus muscle inhibition in patients with symptoms of obstructed defecation, however, suggests that a loss of inhibition capacity progressing from pubococcygeus muscle to puborectalis muscle/external sphincter muscles could determine the insurgence of obstructed defecation symptoms in some subjects, who should therefore benefit from biofeedback retraining aimed at reacquisition of the inhibition capacity of all muscles of the pelvic floor during defecation.

Transanal repair of rectocele corrects obstructed defecation if it is not associated with anismus

PURPOSE

Rectocele is often associated with anorectal symptoms. Various surgical techniques have been described to repair the rectocele. The surgical results are variable. This study evaluated the results of transanal repair of rectocele, with particular emphasis on the impact of concomitant anismus on postoperative functional outcome.

METHODS

Fifty-nine consecutive females who underwent transanal repair of rectocele for obstructed defecation were prospectively reviewed. All 59 patients were parous with a median parity of 2 (range, 1-6) and a median age of 58 (range, 46-68) years. The median length of follow-up was 19 (range, 6-40) months. Anismus was detected by anorectal physiology and defecography. The functional outcome was assessed by a standard questionnaire, physical examination, anorectal manometry, neurophysiology, and defecography. The quality-of-life index was obtained using a visual analog scale (from 1-10, with 10 being the best).

RESULTS

The functional outcome of transanal repair of rectocele was superior in patients without anismus. Forty (93 percent) of the 43 patients without anismus showed improved evacuation after repair compared with 6 (38 percent) of the 16 patients with anismus (P<0.05). The quality-of-life index improved (9 vs. 4) if anismus was not present (P<0.05). There were minimal complications. Hemorrhage requiring blood transfusion (2 units) occurred in one patient and urinary retention in another.

CONCLUSION

Transanal repair of rectocele is safe and, in the absence of anismus, effectively corrects obstructed defecation.

Electromyography of the external anal sphincter: comparison between needle and surface electrodes

PURPOSE

Electromyography of the external anal sphincter is frequently used when investigating patients with defecation disorders. Investigations are often performed using an invasive technique by perineal insertion of a needle or wire electrode. The aim of the present study was to investigate whether surface electromyography, with electrodes applied to the perineal skin, is a reliable method in the diagnosis of paradoxical anal sphincter reaction.

METHODS

Seventy-one patients with defecation disorders participated in the present study. They were investigated with electromyography of the external anal sphincter using surface and needle electrodes.

RESULTS

In 65 of 71 (92 percent) patients the electromyography recording showed the same result during straining using surface electrodes when compared with needle electrodes. Twenty-two of these 65 patients had paradoxical anal sphincter reaction, and 43 patients had decreased electromyography activity. In 6 of 71 (8 percent) patients the electromyography recording showed a different pattern during straining using surface electrodes when compared with needle electrodes.

CONCLUSION

The present study demonstrates a good correlation between surface electrodes applied to the perineal skin and concentric needle electrodes in the diagnosis of paradoxical anal sphincter reaction. Noninvasive electromyography recordings of the external anal sphincter are often preferred in the diagnosis of paradoxical anal sphincter reaction.

Biofeedback for anismus: has placebo effect been overlooked?

OBJECTIVE

Multiple uncontrolled studies have concluded that biofeedback is successful in treating anismus. This study's objective was to assess the physiological effects of placebo and biofeedback treatment on patients with anismus and to correlate changes with clinical improvement.

PATIENTS AND METHODS

Twelve patients with symptoms and electrophysiological findings of anismus were studied. Initial assessment included a detailed history, symptom assessment by linear analogue scales, anorectal manometric and electrophysiological studies, colon transit scintigraphy, and scintigraphic proctography. Patients underwent 5 days of placebo treatment, followed 1 week later by re-assessment of symptoms and physiological studies. Five days of biofeedback was then given followed by another complete re-assessment 1 week later. A final interview was performed 2 months later. All assessments were by an independent observer who was not responsible for the treatments.

RESULTS

Seven patients reported an overall improvement in symptoms following placebo treatment. A total of seven patients reported improvement following biofeedback, three of whom had already reported an improvement with placebo. One patient who reported improvement following placebo had worsening of symptoms following biofeedback. The only symptoms or tests which changed more with biofeedback than placebo were anal pressure and electromyographic activity on attempted defaecation in the left lateral position. There was no demonstrable correlation between change in symptoms and change in physiological tests. The scintigraphic 'ejection fraction' of the rectum was unchanged by treatment.

CONCLUSION

Clinical improvement in previous studies may in part be due to placebo effect and observer bias. Improvement with biofeedback may be due to physiological changes which are not detected with conventional anorectal physiological tests.

Paradoxical sphincter reaction is influenced by rectal filling volume

PURPOSE

Paradoxical sphincter reaction is frequently found in constipated patients but sometimes also in incontinent patients and in asymptomatic subjects. Its significance in defecation disorders has, therefore, been debated. The aim of the present study was to investigate whether paradoxical sphincter reaction is influenced by rectal filling volume.

PATIENTS AND METHODS

Eighteen patients with defecation disorders and paradoxical sphincter reaction shown by electromyography were reinvestigated with an extended electromyographic investigation while in the lying position and while in the sitting position, with 50-ml, 100-ml, and 150-ml water-filled rectal balloons.

RESULTS

All 18 patients showing paradoxical sphincter reaction in the first investigation also showed the reaction at the second investigation in the lying position with a 0-ml volume of rectal contents. In the sitting position, with a volume of 150 ml of rectal contents, the increase in electromyographic activity disappeared in seven patients (39 percent) and no longer showed paradoxical sphincter reaction. Electromyography showed decreased activity in one patient and unchanged activity in six patients during straining. A closing reflex was seen after completed straining in all of these seven patients.

CONCLUSIONS

The present study demonstrates that paradoxical sphincter reaction diagnosed by electromyography is influenced by the rectal filling volume and might diminish when the rectum is filled with contents. The conventional electrophysiologic technique in the diagnosis of paradoxical sphincter reaction might, therefore, overdiagnose this condition.

Rectal wall contractility in response to an evoked urge to defecate in patients with obstructed defecation

PURPOSE

The aim of this study was to examine rectal sensory perception and rectal wall contractility in response to an evoked urge to defecate and to identify differences between control subjects and patients with obstructed defecation.

METHODS

Twenty control patients (10 men; median age, 47 (range, 17-78) years) and 29 female patients with disabling obstructed defecation (median age, 48 (range, 18-70) years) entered the study. Under radiologic control, an infinitely compliant barostat balloon was inserted over a guide wire into the proximal part of the rectum. Additionally, a latex balloon was introduced into the distal part of the rectum. This latex balloon was inflated until an urge to defecate was experienced. Simultaneously, rectal wall contractility was assessed by measuring the variations in barostat balloon volume. These variations were expressed as percentage changes from baseline volume.

RESULTS

By comparing controls and patients with obstructed defecation, a significant difference was found regarding mean distending volume required to elicit an urge to defecate (135 +/- 38 vs. 214 +/- 87 ml of air; P < 0.001, Mann-Whitney U-test). In all controls, the evocation of an urge to defecate induced a pronounced increase in rectal tone, proximal to the distal stimulating balloon. By comparing controls and patients, the increase in rectal tone was found to be significantly higher in control subjects (35 +/- 10 vs. 9 +/- 10 percent; P < 0.001). Twenty-five patients (86 percent) showed no or only minimum (<20 percent) increase in rectal tone during the perception of an urge to defecate. In 14 of these patients, the threshold for this perception was increased. Only four patients (14 percent) showed a relatively normal increase (>20 percent) in rectal tone. However, their threshold for perception was greatly increased.

CONCLUSION

The assembly used in this study provides a useful tool for investigation of rectal evacuation. In all of our patients, obstructed defecation was associated with abnormal rectal sensory perception and/or altered rectal wall contractility.

Anismus: fact or fiction?

PURPOSE

Although anismus has been considered to be the principal cause of anorectal outlet obstruction, it is doubtful whether contraction of the puborectalis muscle during straining is paradoxical. The present study was conducted to answer this question.

METHODS

During the first part of the study, we retrospectively reviewed 121 patients with constipation and/or obstructed defecation (male:female, 10/111; median age, 51 years). All of these patients underwent electromyography (EMG) of the pelvic floor and the balloon expulsion test (BET) in the left lateral position. Evacuation proctography was performed in all of these patients in the sitting position. Both the posterior anorectal angle and the central anorectal angle were measured. EMG and BET were also performed in ten controls (male:female, 4/6; median age, 47). In 147 patients with fecal incontinence (male:female, 24/123; median age, 58) only EMG activity was recorded. Criteria for anismus during straining were increase or insufficient (<20 percent) decrease of EMG activity, failure to expel an air-filled balloon on BET, and decrease or insufficient (<5 percent) increase of anorectal angle on evacuation proctography. Between June 1994 and March 1995, we conducted a second prospective study in a consecutive series of 49 patients with constipation and/or obstructed defecation and 28 patients with fecal incontinence. Both groups were compared with 19 control subjects. In this study, all three tests were performed. EMG and BET were performed both in the left lateral position and in the sitting position.

RESULTS

The retrospective study was undertaken by comparing the constipated patients with the incontinent patients and the controls, and the anismus detected by EMG was found in, respectively, 60, 46, and 60 percent. Failure to expel the air-filled balloon was observed in 80 constipated patients (66 percent) and in 9 control subjects (90 percent). Based on posterior anorectal angle and central anorectal angle measurements, anismus was diagnosed in, respectively, 21 and 35 percent of constipated patients. In the prospective study, none of the tests showed significant differences regarding the prevalence of anismus between the two subgroups of patients and the control subjects. The prevalence of anismus only differed between constipated and incontinent patients when the diagnosis was based on BET in the sitting position (67 vs. 32 percent; P < 0.005). Our study shows that contraction of the puborectalis muscle during straining is not exclusively found in patients with constipation and/or obstructed defecation. The three tests most commonly used for the diagnosis of anismus showed an extremely poor agreement.

CONCLUSION

Based on these findings, we doubt the clinical significance of anismus.

The anal sphincter in idiopathic megarectum: effects of manual disimpaction under general anesthetic

PURPOSE

This study was designed to investigate the function and morphology of anal sphincters in patients with an idiopathic megarectum.

METHOD

A total of 17 patients were studied by anal endosonography and manometry when not impacted. Fourteen had previously been manually disimpacted under general anesthetic, and three had not.

RESULTS

Nine of 14 patients in the former group, but none of the latter group, had disruption of one or both anal sphincter muscles on endosonography. Endosonographic changes were characteristic of those identified previously in patients following anal dilation. Low anal resting pressure, indicative of internal sphincter dysfunction, was found in a substantial proportion of patients with either an endosonographically intact or disrupted internal anal sphincter. Voluntary contraction increment, a reflection of external sphincter function, was normal in all patients.

CONCLUSION

Manual disimpaction under general anesthetic appears to be associated with iatrogenic structural injury to the anal sphincters. In some patients, this may contribute to sphincter weakness. This damage may contribute to the incontinence experienced by patients with a dilated rectum.

Idiopathic megarectum in adults. An assessment of manometric and radiologic variables

Outlet obstruction is thought to be one of the major factors responsible for idiopathic constipation. However, outlet obstruction itself may be due to several mechanisms. Among these, the presence of a megarectum is a leading one. Pathophysiological studies in adult patients with idiopathic megarectum are scarce. We studied by manometric and defecographic means 15 adult subjects with idiopathic megarectum and severe chronic constipation. Twenty-five healthy volunteers of both sexes acted as controls. Manometric variables showed significant differences between patients and controls with respect to internal anal sphincter pressure (P = 0.02), minimum relaxation volume (P < 0.001), defecatory sensory threshold (P < 0.001), mean rectal tolerable volume (P < 0.001), and rectal compliance (P < 0.001). An altered response to straining was observed in 46.6% of patients and in 12% of controls (P < 0.04); the ability to expel a 50-ml balloon per anum was 13.3% in patients and 100% in controls (P < 0.001). Although all patients opened the anorectal angle and had descent of the pelvic floor, thereby confirming an adequate expulsion effort, evacuation of contrast material appeared extremely difficult. In fact, no subject was able to expel more than 30% of the rectal contents during fluoroscopic screening. These results confirm previous hypotheses that idiopathic megarectum displays features of a neuropathic process as an underlying mechanism. Further studies are needed that also take into consideration the muscle tone component of the rectum in these patients.

Anismus as a marker of sexual abuse. Consequences of abuse on anorectal motility

Anorectal manometry was performed in 40 women, who consulted for functional disorders of the lower gastrointestinal tract and had been sexually abused. Anismus, defined as a rise in anal pressure during straining, was observed in 39 of 40 abused women, but in only six of 20 healthy control women (P < 0.0001). Other parameters of anorectal manometry were compared with those observed in another control group composed of 31 nonabused women but with anismus, as well as the group of healthy controls. A decreased amplitude of anal voluntary contraction and an increased threshold volume in perception of rectal distension were observed in both abused and nonabused patients. A decreased amplitude of rectoanal inhibitory reflex, little rise in rectal pressure upon straining, frequent absence of initial contraction during rectal distension, and increased resting pressure at the lower part of the anal canal were observed in abused but not in nonabused patients, suggesting that these abnormalities, in association with anismus, suggest a pattern of motor activity in the anal canal that could be indicative of sexual abuse.

Obstructed defecation: current status of pathophysiology and management

Obstructed defecation poses a challenging clinical problem and in many patients presenting with this syndrome the underlying pathophysiology cannot be determined. Up to now, attempts to diagnose and treat obstructed defecation (anismus) have focused on the function of the somatic pelvic floor musculature surrounding the anorectum, and concepts such as 'puborectalis paradox' and 'spastic pelvic floor' have gained widespread acceptance despite there being no objective data to support such concepts. New evidence showing that defecation is an integrated process of colonic and rectal emptying suggests that anismus may be much more complex than a simple disorder of the pelvic floor muscles. In a small number of patients obstructed defecation is caused by a more simple mechanism, such as internal sphincter hypertonia or a large rectocele, which is easily corrected surgically. Careful selection of patients for treatment, based on identifying the underlying pathophysiological disorder, is emphasized.

Scintigraphic assessment of colonic function during defaecation

The aim of this study was to develop a method by which rectal and colonic activity could be examined during defaecation under physiological conditions, in order to evaluate whether the colon plays a role in defaecation. Subjects presented to the Nuclear Medicine department on the day following ingestion of oral In-111 labelled DTPA, when they developed the normal urge to defaecate. Defaecation took place in a private room while dynamic scintigraphy of the rectum and colon was recorded. Fourteen subjects were studied (8 normal subjects, 4 with constipation, 2 with irritable bowel syndrome). In 13 subjects the left colon was visualized during defaecation and emptying was clearly observed in 12. The right colon was visualised in 11 subjects and emptying was seen in 7. Mean percentage segmental evacuation was right colon 20%, left colon 32% and rectum 66%. Colonic emptying occurs during defaecation, which is not a process of rectal evacuation only. This has implications for the understanding of the pathophysiology of obstructed defaecation.

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.

Anorectal manometry in the diagnosis of paradoxical puborectalis syndrome

This prospective study was undertaken to compare the utility of anorectal manometry (ARM) with that of anal electromyography (EMG) and cinedefecography (CD) in the diagnosis of paradoxical puborectalis syndrome (PPS). One hundred sixteen consecutive patients with a history of chronic constipation were prospectively assessed. These 35 males and 81 females were of a mean age of 60 years, ranging from 18 to 84 years. The incidences of PPS were 63 percent for ARM, 38 percent for EMG, and 36 percent for CD. The correlations of PPS were suboptimal: ARM and EMG, 70 percent; and ARM and CD, 61 percent. A two-tiered system for the manometric classification of PPS was developed. First, the evacuation pressure curve pattern was classified as a normal relaxed downward (Type A; n = 43), a nonrelaxed flat or equivocal (Type B; n = 36), and a paradoxical upward (Type C; n = 37). PPS was noted with increasing incidence within curve types (21 percent in Type A, 64 percent in Type B, and 95 percent in Type C). Second, an evacuation index (EI = evacuation pressure/squeeze pressure) was defined: Group I (EI < 0; n = 43), Group II (0 < or = EI < 0.25; n = 24), Group III (0.25 < or = EI < 0.5; n = 27), and Group IV (EI > or = 0.5; n = 18). The finding of PPS also correlated with the EI group: 21 percent in Group I, 67 percent in Group II, 74 percent in Group III, and 100 percent in Group IV. This subdivision of curve types and EI groups may provide a role in the diagnosis of PPS.

Anismus: the cause of constipation? Results of investigation and treatment

Anismus, or failure of the somatic sphincter apparatus to relax at defecation, has been implicated as a major contributor to the problem of obstructed defecation. Current diagnostic methods depend on laboratory measurements of attempted defecation and the most complex, dynamic proctography has been the mainstay of diagnosis. Using a new computerized ambulatory method of recording sphincter function in these patients at home, we report an 80% reduction in our diagnostic rate suggesting that conventional tests fail to accurately diagnose this condition, probably because they poorly represent the natural physiology of defecation. Treatment of this distressing condition is more complex and a variety of surgical and pharmacological measures have failed. Biofeedback retraining of anorectal function of these patients has been very successful and represents the management of choice.

Paradoxical sphincter reaction and associated colorectal disorders

Of 71 patients with paradoxical sphincter reaction, 54 had symptoms of constipation or outlet obstruction and 17 were incontinent. The patients were investigated with defecography, colon transit time, anorectal manometry and electromyography. Ninety-six percent of the patients had additional changes in anorectal anatomy and physiology; 70% of the patients had abnormal defecography and 42% had delayed colon transit time. Decreased maximal anal pressure (MAP) and maximal squeeze pressure (MSP), indicating impaired function of the anal sphincters might be one reason for incontinence in patients with paradoxical sphincter reaction. The paradoxical reaction occurred in the puborectalis muscle and in three tested sites in the external sphincter. It is sufficient to record the EMG activity in one muscle and at one point to diagnose a paradoxical sphincter reaction. The absence of a normal closing reflex on electromyography is evidence for a paradoxical sphincter reaction. Denervation was more pronounced in the external sphincter than in the puborectalis muscle. The right pudendal nerve was subjected to damage more often than the left nerve.

Partial colectomy and coloanal anastomosis for idiopathic megarectum and megacolon

Adult patients with an idiopathic megarectum or megacolon can experience severe constipation requiring surgical treatment. Some of these patients have a proximal colon of normal diameter, with dilatation involving only the left or distal colon and rectum. The results of partial colonic and rectal resection with coloanal anastomosis in such patients have been reviewed. Seven patients (two female and five male) underwent a coloanal anastomosis over a seven-year period. The median age at operation was 19 years, the mean age at onset of symptoms was five years, and the mean follow-up period was one year. Five patients experienced a return to normal bowel frequency with the loss of most symptoms. One patient has an ileostomy because of persistent constipation after the procedure. One subject died because of postoperative bleeding from the anastomosis and subsequent cardiac and respiratory complications. This operation may have a place in the treatment of severe constipation caused by idiopathic megarectum and megacolon, but careful preoperative motility studies and meticulous attention to operative technique are required for a good outcome.

Biofeedback defaecation training for anismus

Anismus, paradoxical external sphincter function, spastic pelvic floor syndrome, rectoanal dysnergia, abdomino-levator incoordination for abdominopelvic asychronism, are all due to paradoxical contraction of the striated sphincter apparatus during voiding and is characterised by prolonged and excessive straining at stool. Biofeedback is the treatment of choice and has to be introduced at an early stage. We present the results of an ambulatory approach based on the integration of simulated balloon defaecation with small (50 ml) as well as constant rectal sensation volume, defaecometry and anal manometry. The pathophysiology visualised by the patient's own anorectal pressure recordings on the screen of a personal computer is explained and corrected. Sixteen patients were treated and followed for at least 1 year. Manometric data were normal except for an increased minimum residual pressure and rectal compliance. Nine patients could not evacuate a 50 ml bolus initially. Simulated defaecation became possible in seven out of these nine patients when the bolus was increased up to the individual constant rectal sensation volume. Two patients could not evacuate this volume either, while defaecation was made much less laborious in the other seven patients. Paradoxical contraction was immediately corrected in 7/16 cases. Also, as an immediate, objective benefit of a single training session, improved defaecation of a 50 ml bolus was observed in 11 patients. This effect was preserved after 6 weeks in nine cases; symptomatic recurrence did not occur in these patients during follow-up. This method of defaecation training has many advantages as compared with sphincter training using EMG electrodes eventually performed in the absence of a desire to defaecate or in lying position.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment and treatment of obstructed defecation

Defecation may be considered as "the last taboo". The inability to defecate, or to achieve it only by digital evacuation, has never been a popular topic among patients and doctors. The extensive development of tests in laboratories studying colorectal disorders during recent years, however, has made it possible to study the different parts of the mechanism for maintaining continence. Since constipation is a disorder of this mechanism, namely a disorder of rectal evacuation, application of these tests on constipated patients is logical. Certainly surgery, either colectomy or sphincter division, is not the solution, nor is the injection of muscle weakening solutions. Biofeedback, however, seems to be a logical treatment. Development of new functional tests and strategies is needed to enable a better understanding of the problem. Collaboration between surgeon and psychologist has proved valuable and is recommended.

Clinical indications for anorectal function investigations

Interest in anorectal function investigation tests has increased, and new investigation techniques have been introduced, gaining new insight in the pathogenesis of fecal incontinence and constipation. Normal values in anorectal function tests have shown a large overlap between controls and patients with fecal incontinence or constipation. Therefore, the pure clinical indications for the individual anorectal function tests are small, and the strength comes from combining these test results. When the patient is not eligible for surgery or biofeedback, there is no indication to perform anorectal function tests. Guidelines for selective use of anorectal function tests are given. In patients with fecal incontinence, the clinical consequence of demonstrating severe pudendal neuropathy is not yet clear. Defecography is important to demonstrate an intussusception as a treatable cause of incontinence. In patients with constipation an anal EMG (of defecography) can diagnose the spastic pelvic floor syndrome, which should be treated with relaxation exercises or biofeedback. Patients with other anorectal diseases, patients receiving a stoma, and patients considered for reanastomosis operation after (partial) colectomy may benefit from anorectal function tests.