Fatigability of the external anal sphincter in anal incontinence

Optimizing techniques for measuring anal resting and squeeze pressures with high-resolution manometry

BACKGROUND

The optimal methods for measuring and analyzing anal resting and squeeze pressure with high-resolution manometry (HRM) are unclear.

METHODS

Anal resting and squeeze pressures were measured with HRM in 90 healthy women, 35 women with defecatory disorders (DD), and 85 with fecal incontinence (FI). Pressures were analyzed with Manoview™ software and a customized approach. Resting pressures measured for 20, 60, and 300 s were compared. During the squeeze period, (3 maneuvers, 20 s each), the squeeze increment, which was averaged over 5, 10, 15, and 20 s, and squeeze duration were evaluated.

RESULTS

Compared to healthy women, the anal resting pressure, squeeze pressure increment, and squeeze duration were lower in FI (p ≤ 0.04) but not in DD. The 20, 60, and 300 s resting pressures were strongly correlated (concordance correlation coefficients = 0.96-0.99) in healthy and DD women. The 5 s squeeze increment was the greatest; 10, 15, and 20 s values were progressively lower (p < 0.001). The squeeze pressure increment and duration differed (p < 0.01) among the three maneuvers in healthy and DD women but not in FI women. The upper 95th percentile limit for squeeze duration was 19.5 s in controls, 19.9 s in DD, and 19.3 s in FI. Adjusted for age, resting pressure, and squeeze duration, a greater squeeze increment was associated with a lower risk of FI versus health (OR, 0.96; 95% CI, 0.94-0.97).

CONCLUSIONS

These findings suggest that anal resting and squeeze pressures can be accurately measured over 20 s. In most patients, one squeeze maneuver is probably sufficient.

Anal sphincter fatigability in assessing anal incontinence: A systematic review

BACKGROUND

Diagnosing anal incontinence (AI) based on manometry results is challenging due to the variation of the normal values and overlap between patients with and without AI. This study aimed to perform a systematic review on the difference in sphincter fatigability between patients with and without AI.

METHODS

MEDLINE, EMBASE, SCOPUS, and Google Scholar were searched. Studies were included if they included adult patients and assessed anal sphincter fatigability between using manometry. The effect size was estimated as the standardized mean difference (SMD) with 95% confidence intervals. A random-effects model was used.

RESULTS

The database searches identified 125 unique articles, and five additional articles were identified from the reference list of articles. One hundred thirteen were excluded through title and abstract review. Nine articles were included in the final analysis. There was no statistically significant difference in the resting pressure between the two groups. Patients with AI had significantly lower squeeze pressure. There was no statistically significant difference between the groups in the fatigue rate. The FRI was significantly lower in patients with AI (SMD 1.636, p = 0.001). Approximately a third of the patients in one study were able to maintain a contraction for 20s without reducing pressure. There was significant heterogeneity in the studies. The data available were inadequate for more robust calculations.

CONCLUSIONS

Sphincter fatigability, measured by the Fatigability Rate Index, has good discriminating power for anal incontinence. A standardized protocol needs to be followed by future researchers. Graphical Abstract The analysis used six studies with 413 patients to compare Fatigue Rate Index between patients with AI and controls. All studies reported a lower FRI in patients with incontinence and the FRI was significantly lower in patients with AI (standardized mean difference [SMD] 1.636, p= 0.001). Conflicting results were reported on the correlation between FRI and AI symptom scores.

Faecal incontinence in adults

Faecal incontinence, which is defined by the unintentional loss of solid or liquid stool, has a worldwide prevalence of ≤7% in community-dwelling adults and can markedly impair quality of life. Nonetheless, many patients might not volunteer the symptom owing to embarrassment. Bowel disturbances, particularly diarrhoea, anal sphincter trauma (obstetrical injury or previous surgery), rectal urgency and burden of chronic illness are the main risk factors for faecal incontinence; others include neurological disorders, inflammatory bowel disease and pelvic floor anatomical disturbances. Faecal incontinence is classified by its type (urge, passive or combined), aetiology (anorectal disturbance, bowel symptoms or both) and severity, which is derived from the frequency, volume, consistency and nature (urge or passive) of stool leakage. Guided by the clinical features, diagnostic tests and therapies are implemented stepwise. When simple measures (for example, bowel modifiers such as fibre supplements, laxatives and anti-diarrhoeal agents) fail, anorectal manometry and other tests (endoanal imaging, defecography, rectal compliance and sensation, and anal neurophysiological tests) are performed as necessary. Non-surgical options (diet and lifestyle modification, behavioural measures, including biofeedback therapy, pharmacotherapy for constipation or diarrhoea, and anal or vaginal barrier devices) are often effective, especially in patients with mild faecal incontinence. Thereafter, perianal bulking agents, sacral neuromodulation and other surgeries may be considered when necessary.

THE FATIGUE RATE INDEX IS HIGHER IN CHILDREN WITH FUNCTIONAL CONSTIPATION AND RETENTIVE FECAL INCONTINENCE

BACKGROUND

The Fatigue Rate Index (FRI) is a parameter in anorectal manometry (ARM) to assess sustained voluntary contraction, considering the squeeze pressure and fatigability of the external anal sphincter. It is used in adults to detect fecal incontinence even in patients who present normal squeeze pressures. The FRI in adult patients with functional constipation is similar to controls.

OBJECTIVE

The aim of this study was to evaluate the feasibility and values of FRI in children in relation to the values previously established in adults and comparing children with functional constipation and retentive fecal incontinence to children without retentive fecal incontinence.

METHODS

This retrospective study evaluated 105 ARM performed from Jan 2014 to Apr 2015. 42 patients were selected (were able to perform a voluntary contraction and had no co-morbidities other than functional constipation). 14 (33.3%) of those collaborated in sustaining contraction for 40 seconds (s), allowing the evaluation of the FRI. Patients with retentive fecal incontinence secondary to functional constipation (n=7, aged 6 to 13 years, six boys) were our interest group. Patients with functional constipation without fecal incontinence (n=7, aged 6 to 13 years, four boys) were considered a reference group. The ARM were performed with a radial eight-channel perfusion catheter (DynamedTM, São Paulo, Brazil) and the FRI was calculated (Proctomaster 6.4) in the first 20 s and overall 40 s of sustained voluntary contraction.

RESULTS

14 of the selected 42 collaborated in sustaining contraction for 40 s, allowing the evaluation of the FRI. In the first 20 s of contraction, the fecal incontinence group showed a significantly higher mean FRI (2.48±1.39 min) compared to the reference group (1.13±0.72 min, P=0.042), which was not observed in the 40 s interval due to less uniform contraction. The anal resting pressure was higher in the fecal incontinence group (76.83 mmHg) than in the reference group (54.13 mmHg), but the statistical study did not reach significance (P=0.051).

CONCLUSION

The FRI is feasible in children. The mean FRI obtained in this study is lower than the reported in constipated adults. The mean FRI among children with functional constipation and retentive fecal incontinence is higher than among constipated children without retentive fecal incontinence.

Fatigability of the external anal sphincter muscles using a novel strength training resistance exercise device

Exercises involving pelvic floor muscles including repetitive voluntary contractions of external anal sphincter (EAS) musculature have been used to improve fecal incontinence. Muscle fatigue is a prerequisite for successful strength training. However, muscle fatigue induced by these exercises has not been systematically studied. We aimed to assess the fatigability of EAS muscles during various exercise methods. Twelve nulliparous (21 ± 2.7 yr) women were studied. We evaluated fatigue during 40 repetitive 3-s contractions and 30-s long squeeze contractions both with and without an intra-anal compressible resistant load. The sequence of exercises was randomized. This load was provided by the continence muscles Resistance Exerciser Device. Anal canal pressures were recorded by high-resolution manometry. Exercise against a resistive load showed significant decrease in anal contractile integral (CI) and maximum squeeze pressure during repetitive short squeeze contractions compared with exercise without a load. Linear regression analysis showed a significant negative correlation between anal CI and successive contraction against load, suggesting "fatigue." Similar findings were observed for maximum squeeze pressure (slope with load = -4.2, P = 0.0003, vs. without load = -0.9, P = 0.3). Long squeeze contraction against a load was also more susceptible to fatigue than without a load (P < 0.0001). In conclusion, repetitive contractions against a compressible load induce fatigue and thus have the potential to strengthen the anal sphincter contractile function than contractions without a load. Fatigue rate in long squeeze contraction exercises with a load is significantly faster than that without a load, also indicating greater effectiveness in inducing muscle fatigue.NEW & NOTEWORTHY Fecal incontinence is a distressing disorder with a mainstay of treatment being pelvic floor muscle exercises. However, none of these exercises has proven occurrence of fatigability, which is an important prerequisite for successful muscle strengthening in rehabilitative exercises. In this study, we proved that we can fatigue the external anal sphincter muscles more efficiently by providing a resistive load during anal repetitive short squeeze contractions and long squeeze contraction exercise.

External Anal Sphincter Fatigability: An Electromyographic and Manometric Study in Patients With Anorectal Disorders

Background/Aims

External anal sphincter (EAS) plays an important role in fecal and gas voluntary continence. Like every muscle, it can be affected by repeated efforts due to fatigability (physiological response) and/or fatigue (pathological response). No standardized fatiguing protocol and measure method to assess EAS fatigability has existed. The aim is to test a simple, standardized protocol for fatiguing and measuring EAS fatigability and fatigue to understand better the part of EAS fatigability in the pathophysiology of fecal incontinence.

Methods

Patients with anorectal disorders evaluated with anorectal manometry were included. They had to perform 10 repetitions of maximum voluntary contraction (MVC) of 20 seconds. Measurement was made with an anorectal manometry catheter and a surface recording electromyography (EMG). The primary outcome was the difference in EMG root mean square between the first and the last MVC. Secondary outcomes were differences in other EMG and manometry parameters between the first and the last MVC. Difficulties and adverse effects were recorded.

Results

Nineteen patients underwent the fatiguing protocol. All patients completed the entire protocol and no complications were found. No difficulty was declared by the examiner. A significant decrease in root mean square was found between the first and last MVC (0.01020 ± 0.00834 mV vs 0.00661 ± 0.00587 mV; P = 0.002), in maximum anal pressure area under the curve of continuous recordings of anal pressure and mean and total EMG power (P < 0.05).

Conclusions

This protocol is simple and minimally invasive to measure EAS fatigue and fatigability. We highlighted a fatigue of EAS in many patients with anorectal disorders.

Pelvic floor rehabilitation for defecation disorders

Pelvic floor rehabilitation is frequently recommended for defecation disorders, in both constipation and fecal incontinence. However, the lack of patient selection, together with the variety of rehabilitation methods and protocols, often jeopardize the results of this approach, causing difficulty in evaluating outcomes and addressing proper management, and above all, in obtaining scientific evidence for the efficacy of these methods for specific indications. The authors represent different gastroenterological and surgical scientific societies in Italy, and their aim was to identify the indications and agree on treatment protocols for pelvic floor rehabilitation of patients with defecation disorders. This was achieved by means of a modified Delphi method, utilizing a working team (10 members) which developed the statements and a consensus group (15 members, different from the previous ones) which voted twice also suggesting modifications of the statements.

Review of pelvic and perineal neuromuscular fatigue: Evaluation and impact on therapeutic strategies

BACKGROUND

Pelvic floor fatigue is known by its clinical consequences (fecal incontinence, stress urinary incontinence, pelvic organ prolapse), but there are still few studies on the subject.

OBJECTIVE

This article presents an overview of the current knowledge of pelvic and perineal fatigue, focusing on its assessment and consequences in terms of evaluation and therapeutic strategies, to propose an evaluation that could be routinely performed.

METHODS

We performed a systematic review of the literature in MEDLINE via PubMed and Cochrane Library databases by using the keywords pelvic floor, muscular fatigue, physiopathology, stress urinary incontinence, pelvic organ prolapse, fecal incontinence, physical activity, and pelvic rehabilitation. We included reports of systematic reviews and retrospective and prospective studies on adult humans and animals in English or French published up to April 2018 with no restriction on start date.

RESULTS

We selected 59 articles by keyword search, 18 by hand-search and 3 specific guidelines (including the 2009 International Continence Society recommendations); finally 45 articles were included; 14 are described in the Results section (2 reviews of 6 and 20 studies, and 12 prospective observational or cross-over studies of 5 to 317 patients including 1 of animals). Perineal fatigue can be assessed by direct assessment, electromyography and spectral analysis and during urodynamics. Because pelvic floor fatigue assessments are not evaluated routinely, this fatigability is not always identified and is often falsely considered an exclusive pelvic floor weakness, as suggested by some rehabilitation methods that also weaken the pelvic floor instead of enhancing it.

CONCLUSION

Pelvic floor fatigue is not evaluated enough on a routine basis and the assessment is heterogeneous. A better knowledge of pelvic floor fatigue by standardized routine evaluation could lead to targeted therapeutic strategies.

Expert consensus document: Advances in the evaluation of anorectal function

Faecal incontinence and evacuation disorders are common, impair quality of life and incur substantial economic costs worldwide. As symptoms alone are poor predictors of underlying pathophysiology and aetiology, diagnostic tests of anorectal function could facilitate patient management in those cases that are refractory to conservative therapies. In the past decade, several major technological advances have improved our understanding of anorectal structure, coordination and sensorimotor function. This Consensus Statement provides the reader with an appraisal of the current indications, study performance characteristics, clinical utility, strengths and limitations of the most widely available tests of anorectal structure (ultrasonography and MRI) and function (anorectal manometry, neurophysiological investigations, rectal distension techniques and tests of evacuation, including defecography). Additionally, this article provides our consensus on the clinical relevance of these tests.

High-Resolution Anorectal Manometry - New Insights in the Diagnostic Assessment of Functional Anorectal Disorders

Functional anorectal disorders such as faecal incontinence (FI), functional anorectal pain, and functional defecation disorders (FDD) are highly prevalent and represent a high socioeconomic burden. Several tests of anorectal function exist in this setting; however, high-resolution anorectal manometry (HR-ARM) is a new tool that depicts pressure all along the anal canal and can assess rectoanal coordination. HR-ARM is used in the diagnosis of FI and especially FDD although data in health is still sparse, and pressure phenomena seen during simulated defecation, such as dyssynergia, are highly prevalent in health.

Compound muscle action potential of the external anal sphincter

AIM

Pudendal nerve terminal motor latency (PNTML) assesses distal innervation of the external anal sphincter (EAS) but it is insensitive to early nerve damage. We propose to extend the assessment of PNTML to the measurement of the compound muscle action potential (CMAP) of the EAS to understand its progressive denervation.

METHOD

Ninety women with faecal incontinence were prospectively examined and compared with 36 asymptomatic women who acted as controls. PNTML was performed bilaterally and the muscle response analysed for CMAP to include amplitude, area and duration. Anorectal manometry was measured by a station-pull technique using a water-filled microballoon. spss version 11.5 was used for statistical analysis.

RESULTS

In asymptomatic women the CMAP on the left side was greater in nulliparous (n = 7) than parous (n = 27, P < 0.05) individuals. There was a positive correlation with maximum squeeze pressure and area on the left side (P < 0.05, r = 0.397). In women with faecal incontinence, CMAP on the left side had a negative correlation with age (n = 75, P < 0.05), there was no correlation with parity or anorectal manometry. Nulliparous asymptomatic women had a greater CMAP (P < 0.05) on the left side than asymptomatic parous women and parous women with faecal incontinence. Right-side measurements were not conclusive.

CONCLUSION

Compound muscle action potential demonstrated progressive denervation with age in women with faecal incontinence but did not reliably identify early signs of denervation in asymptomatic women. The area on the left side related to muscle function in asymptomatic women but not in women with faecal incontinence. CMAP can distinguish between parous women with faecal incontinence and nulliparous asymptomatic women but is not a useful test of function of the EAS.

Urethral sphincter fatigue after robot-assisted radical prostatectomy: descriptive questionnaire-based study and anatomic basis

OBJECTIVE

To investigate the hypothesis that preservation of the neurovascular bundle (NVB) contributes to the recovery from sphincter fatigue symptoms after robot-assisted radical prostatectomy (RARP) and to examine the sarcolemmal localization of neuronal nitric oxide synthase (nNOS) and nNOS-positive nerves supplying striated muscles in the pelvic floor.

METHODS

Whether preservation of the NVB influences early continence or sphincter fatigue symptoms was examined in 211 consecutive patients undergoing RARP. Continence and sphincter fatigue symptoms were assessed at 1, 3, and 6 months after surgery. An anatomic study was performed using semiserial sections obtained from 14 male cadavers. The association of continence rate and sphincter fatigue symptoms with preservation of the NVB was assessed by the chi-square test.

RESULTS

There was a significant difference across the bilateral, unilateral, and non-nerve-sparing groups with regard to sphincter fatigue symptoms at 1 month (P=.0004) and 3 months (P=.0326) postoperatively. Sarcolemmal nNOS was detected in the rhabdosphincter (mean, 0.57 per 10 muscle fibers) and levator ani (mean, 1.13 per 10 fibers), with fibers originating from periprostatic nNOS-positive nerves.

CONCLUSION

Postoperative sphincter fatigue was reduced by NVB preservation, suggesting that decreased sphincter fatigue may contribute to improvement of continence after RARP. As a background, existence of sarcolemmal nNOS and nNOS-positive nerve terminals arising from the NVB was confirmed in male pelvic floor striated muscles.

Normal values for high-resolution anorectal manometry in healthy women: effects of age and significance of rectoanal gradient

OBJECTIVES

High-resolution manometry (HRM) is used to measure anal pressures in clinical practice but normal values have not been available. Although rectal evacuation is assessed by the rectoanal gradient during simulated evacuation, there is substantial overlap between healthy people and defecatory disorders, and the effects of age are unknown. We evaluated the effects of age on anorectal pressures and rectal balloon expulsion in healthy women.

METHODS

Anorectal pressures (HRM), rectal sensation, and balloon expulsion time (BET) were evaluated in 62 asymptomatic women ranging in age from 21 to 80 years (median age 44 years) without risk factors for anorectal trauma. In total, 30 women were aged <50 years.

RESULTS

Age is associated with lower (r=-0.47, P<0.01) anal resting (63 (5) (≥50 years), 88 (3) (<50 years), mean (s.e.m.)) but not squeeze pressures; higher rectal pressure and rectoanal gradient during simulated evacuation (r=0.3, P<0.05); and a shorter (r=-0.4, P<0.01) rectal BET (17 (9) s (≥50 years) vs. 31 (10) s (<50 years)). Only 5 women had a prolonged (>60 s) rectal BET but 52 had higher anal than rectal pressures (i.e., negative gradient) during simulated evacuation. The gradient was more negative in younger (-41 (6) mm Hg) than older (-12 (6) mm Hg) women and negatively (r=-0.51, P<0.0001) correlated with rectal BET but only explained 16% of the variation in rectal BET.

CONCLUSIONS

These observations provide normal values for anorectal pressures by HRM. Increasing age is associated with lower anal resting pressure, a more positive rectoanal gradient during simulated evacuation, and a shorter BET in asymptomatic women. Although the rectoanal gradient is negatively correlated with rectal BET, this gradient is negative even in a majority of asymptomatic women, undermining the utility of a negative gradient for diagnosing defecatory disorders by HRM.

Fatigue rate of the external anal sphincter

AIM

Studies of skeletal muscle show that fatigue rate corresponds to the proportion of fast-twitch and slow-twitch fibres that are present in the muscle. Limited work has been done on the fatigue rate of the external anal sphincter. We have prospectively studied fatigability of the external anal sphincter in women with faecal incontinence and women with normal bowel control.

METHOD

Anorectal manometry was measured by a station-pull technique using a water-filled microballoon. Fatigue rate was calculated from anal pressure measurements taken every 0.1 s over a 20-s squeeze.

RESULTS

Women with faecal incontinence (n=88, median -12 cmH(2) O/min) were less susceptible to fatigue than women with normal bowel control (n=36, median -43 cmH(2) O/min) (P<0.01). The external anal sphincter was less susceptible to fatigue with increasing age (P<0.01, r=0.499). In women with normal bowel control and in women with faecal incontinence fatigue rate was negatively correlated with maximum squeeze pressure (P<0.01, r=-0.287; P<0.01, r=-0.579).

CONCLUSION

The external anal sphincter was less susceptible to fatigue with increasing age. Women with faecal incontinence have a weaker but more fatigue-resistant external anal sphincter. This might correspond to a higher proportion of slow-twitch muscle fibres. Histological studies are needed to examine this hypothesis.

Biofeedback for fecal incontinence: a randomized study comparing exercise regimens

BACKGROUND

Fecal incontinence affects up to 11% of Australian community-dwelling adults and 72% of nursing home residents. Biofeedback is a recommended conservative therapy when medication and pelvic floor exercises have failed to improve patient outcomes.

OBJECTIVE

This study aimed to investigate the impact of a new exercise regimen on the severity of fecal incontinence and the quality of life of participants.

DESIGN

This was a randomized clinical study.

SETTINGS

This study was conducted at the Anorectal Physiology Clinic, Townsville Hospital, Queensland, Australia.

PATIENTS

Seventy-two participants (19 male), with a mean age of 62.1 years, attended 5 clinic sessions: 4 weekly sessions followed by 4 weeks of home practice and a follow-up assessment session. A postal survey was conducted 2 years later.

INTERVENTION

Thirty-seven patients (12 male) were randomly assigned to the standard clinical protocol (sustained submaximal anal and pelvic floor exercises) and 35 patients (7 male) were randomly assigned to the alternative group (rapid squeeze plus sustained submaximal exercises).

MAIN OUTCOME MEASURES

The main outcomes were measured by use of the Cleveland Clinic Florida Fecal Incontinence score and the Fecal Incontinence Quality of Life Scale survey tool.

RESULTS

No significant differences were found between the 2 exercise groups at the beginning or at the end of the study or as a result of treatment in objective, quality-of-life, or fecal incontinence severity measures. Sixty-nine participants completed treatment. The severity of fecal incontinence decreased significantly (11.5/20 to 5.0/20, P < .001). Eighty-six percent (59/69) of participants reported improved continence. Quality of life significantly improved for all participants (P < .001). Results were sustained 2 years later. Patients who practiced at least the prescribed number of exercises had better outcomes than those who practiced fewer exercises.

LIMITATIONS

This study was limited because it involved a heterogeneous sample, it was based on subjective reporting of exercise performance, and loss to follow-up occurred because of the highly mobile population.

CONCLUSIONS

Patients attending this biofeedback program attained significant improvement in the severity of their fecal incontinence and in their quality of life. Although introduction of rapid muscle squeezes had little impact on fecal incontinence severity or patient quality of life, patient exercise compliance at prescribed or greater levels did.

Increased fatigability of external anal sphincter in inflammatory bowel disease: significance in fecal urgency and incontinence

BACKGROUND AND AIMS

Fatigability of external anal sphincter (EAS) has not been studied in inflammatory bowel disease (IBD) patients. We evaluated EAS fatigability in IBD patients with and without fecal incontinence (FI) and urgency, and correlated fatigability with demographic and clinical factors, and EAS endosonography.

METHODS

Fifty-eight consecutive IBD cases and 14 healthy volunteers completed Bristol stool form and a FI severity scale. Groups I, II and III included 27 patients with urgency including 13 with concomitant FI, 31 patients without FI or urgency, and 14 controls, respectively. We performed stationary pull-through manometry with an 8-channel water-perfused catheter. Fatigue rate (FR) was calculated by linear regression during a 20-s anal squeeze, and fatigue rate index (FRI) as the ratio of squeeze pressure increment to FR. EAS thickness and deficits were evaluated with an endoanal 10-MHz probe. Patients underwent sigmoidoscopy.

RESULTS

Group I demonstrated a higher Bristol score, more frequent defecations, and more EAS defects compared to group II. Resting, peak squeeze pressures and EAS thickness did not differ between groups. FR was increased in group I versus II, and in group II versus III; FRI was decreased in group I versus II and in group II versus III (p<0.001, adjusting for age and BMI). Gender, oral glucocorticoids, presence of proctitis, perianal disease and EAS defects did not interact with group membership on FR or FRI.

CONCLUSIONS

IBD is associated with increased fatigue rate and decreased fatigue rate index. These differences were even more striking in patients with incontinence or urgency.

Changes in fatigability of the striated anal canal after childbirth

AIM

Anal manometry is an established assessment tool for patients with faecal incontinence. Fatigue rate index (FRI) has been shown to discriminate between symptomatic patients and controls. The aim of this study was to compare manometry and fatigability of the anal canal in nulliparous women before and after childbirth.

METHOD

An air-filled manometry device was used to record maximum resting and squeeze pressures, fatigue rate (recorded over 20 s) and FRI. Recordings were made before and after vaginal delivery.

RESULTS

Nineteen women were studied. Resting anal canal pressure was not significantly different before and after delivery (57.1 +/- 13.6 vs 51.1 +/- 11.9 cmH(2)O, P = 0.1). Squeeze pressure was significantly lower postpartum (106.5 +/- 43.6 vs 75.5 +/- 45.6 cmH(2)O, P < 0.001). Fatigue rate was significantly reduced postpartum (-129.5 +/- 74.7 vs-76.1 +/- 54.8 cmH(2)O/min, P = 0.001), but FRI was not significantly altered (1.23 +/- 1.49 vs 1.41 +/- 1.27 min, P = 0.09).

CONCLUSION

Maximal squeeze pressure and fatigue rate of the anal canal are significantly reduced after childbirth. Resting anal canal pressure and FRI are not significantly different.

Anal physiology testing in fecal incontinence: is it of any value?

INTRODUCTION

The prognostic value of postoperative manometry in fecal incontinence is still controversial. The aims of this study were to establish if Fecal Incontinence Severity Index (FISI) and Fecal Incontinence Quality of Life Scale (FIQL) scores correlate with anal manometry and endoanal ultrasound findings and to define if there is any prognostic value in performing anal manometry after patients are surgically treated for fecal incontinence.

METHODS

Fifty-three patients, all women, were identified. All patients underwent a surgical procedure and were analyzed pre- and postoperatively. Fecal incontinence was assessed using the FISI and FIQL. Patients who did not have these score were excluded. Manometry and ultrasound findings before treatment and manometry findings after treatment were compared with surgical patient's incontinence scores. Anal canal length was noted, and its association with the pre- and postoperative manometry finding and incontinence scores were compared.

RESULTS

No correlation of pre- and postoperative resting and squeeze pressures with incontinence scores was found. Ultrasound findings had no correlation with manometry results and incontinence scores. Anal canal length correlated with both pre- and postoperative manometry findings but not with incontinence scores.

CONCLUSION

Preoperative anal manometry and endoanal ultrasound help in guiding treatment options in patients with fecal incontinence. A decrease in FISI and increase in FIQL scores after a sphincter repair quantifies improvement after incontinence surgery, while changes in anal manometry pressures readings do not.

Function and dysfunction of the colon and anorectum in adults: working team report of the Swedish Motility Group (SMoG)

Symptoms of fecal incontinence and constipation are common in the general population. These can, however, be unreliably reported and are poorly discriminatory for underlying pathophysiology. Furthermore, both symptoms may coexist. In the elderly, fecal impaction always must be excluded. For patients with constipation, colon transit studies, anorectal manometry and defecography may help to identify patients with slow-transit constipation and/or pelvic floor dysfunction. The best documented medical treatments for constipation are the macrogols, lactulose and isphagula. Evolving drugs include lubiprostone, which enhances colonic secretion by activating chloride channels. Surgery is restricted for a highly selected group of patients with severe slow-transit constipation and for those with large rectoceles that demonstrably cause rectal evacuatory impairment. For patients with fecal incontinence that does not resolve on antidiarrheal treatment, functional and structural evaluation with anorectal manometry and endoanal ultrasound or magnetic resonance (MR) of the anal canal may help to guide management. Sacral nerve stimulation is a rapidly evolving alternative when other treatments such as biofeedback and direct sphincter repair have failed. Advances in understanding the pathophysiology as a guide to treatment of patients with constipation and fecal incontinence is a continuing important goal for translational research. The content of this article is a summary of presentations given by the authors at the Fourth Meeting of the Swedish Motility Group, held in Gothenburg in April 2007.

Contractile properties of the denervated external anal sphincter

OBJECTIVE

The purpose of this study was to evaluate the effect of denervation on contractile properties of the external anal sphincter (EAS) of the female rat.

STUDY DESIGN

Sham operation, pudendal nerve transection, pelvic neurectomy, or combined pudendal nerve transection/pelvic neurectomy was performed in young female rats. Contractile function of the EAS was determined after 2 weeks.

RESULTS

Maximal force-generating capacity of the EAS was not impaired by bilateral pudendal denervation or pelvic neurectomy. Twitch tension, however, was decreased, and fatigability increased after pelvic neurectomy. Combined bilateral pudendal nerve-transection plus pelvic neurectomy resulted in compromised force-generating capacity, decreased twitch tension, and increased fatigability of the anal sphincter.

CONCLUSION

Subtle changes in EAS function are detectable after pelvic neurectomy, but not pudendal denervation. In contrast, combination pudendal and pelvic neurectomy resulted in severe compromise of EAS function. These data suggest that EAS function is relatively preserved unless injury occurs to > 1 source of innervation.

Manometric, sensorimotor, and neurophysiologic evaluation of anorectal function

With advances in diagnostic technology, it is now accepted that in the field of functional bowel disorders, symptom-based assessment is unsatisfactory as the sole means of directing therapy. A robust taxonomy based on underlying pathophysiology has been suggested, highlighting a crucial role for physiologic testing in clinical practice. A wide number of complementary investigations currently exist for the assessment of anorectal structure and function, some of which have a clinical impact in patients with functional disorders of evacuation and continence by markedly improving diagnostic yield and altering management. The techniques, limitations, measurements, and clinical use of manometric, sensorimotor, and neurophysiologic tests of anorectal function are presented.

External anal sphincter fatigue is not improved by N-acetylcysteine in an animal model

Oxidative stress is associated with skeletal muscle fatigue. This study tests the hypotheses that N-acetylcysteine (NAC) reduces fatigue and accelerates recovery of the rat external anal sphincter (EAS). Fifteen female Wistar rats were killed humanely. The EAS was mounted as a ring preparation and electrically stimulated with 50 Hz trains of 200 ms in duration every 4 s for three and a half minutes. Three groups were analysed: a control group (n = 5), a group pretreated with NAC (10(-4) mol L(-1); n = 5) and a group pretreated with NAC (10(-3) mol L(-1); n = 5). A novel fatigue index was formulated and was compared to a conventional method of expressing fatigue. There was no significant difference at concentrations of NAC (10(-4) mol L(-1); P > 0.05). At high concentrations of NAC (10(-3) mol L(-1)) there was a significant depression in peak twitch amplitude before fatigue (P = 0.04). N-acetylcysteine in both concentrations used, did not alter fatigue or recovery of the rat EAS. There was a significant positive correlation between the two methods of expressing fatigue but the conventional method produced a higher fatigue index (22.4% on average). N-acetylcysteine does not ameliorate fatigue or accelerate recovery of the EAS and may not be a useful medical therapy for faecal incontinence.

Investigation and treatment of faecal incontinence

Faecal incontinence is a debilitating condition affecting people of all ages, and significantly impairs quality of life. Proper clinical assessment followed by conservative medical therapy leads to improvement in more than 50% of cases, including patients with severe symptoms. Patients with advanced incontinence or those resistant to initial treatment should be evaluated by anorectal physiology testing to establish the severity and type of incontinence. Several treatment options with promising results exist. Patients with gross sphincter defects should undergo surgical repair. Those who fail to respond to sphincteroplasty and those with no anatomical defects have the option of either sacral nerve stimulation or other advanced procedures. Stoma formation should be reserved for patients who do not respond to any of the above procedures.