The role of pelvic floor denervation in the aetiology of idiopathic faecal incontinence

Descending perineum syndrome: a review of the presentation, diagnosis, and management

INTRODUCTION AND HYPOTHESIS

Defecatory dysfunction is a relatively common and challenging problem among women and one that practicing pelvic reconstructive surgeons and gynecologists deal with frequently. A subset of defecatory dysfunction includes obstructed defecation, which can have multiple causes, one of which is descending perineum syndrome (DPS).

METHODS

A literature search was performed to identify the pathophysiology, diagnosis, and management of DPS.

RESULTS

Although DPS has been described in the literature for many decades, it is still uncommonly diagnosed and difficult to manage. A high index of suspicion combined with physical examination consistent with excess perineal descent, patient symptom assessment, and imaging in the form of defecography are required for the diagnosis to be accurately made. Primary management options of DPS include conservative measures consisting of bowel regimens and biofeedback. Although various surgical approaches have been described in limited case series, no compelling evidence can be demonstrated at this point to support surgical intervention.

CONCLUSIONS

Knowledge of DPS is essential for the practicing pelvic reconstructive surgeon to make a timely diagnosis, avoid harmful treatments, and initiate therapy early on.

The PNEI holistic approach in coloproctology

The psycho-neuroendocrine-immune approach relies on the concept of considering diseases from a holistic point of view: the various components (psyche, nervous system, endocrine system, and immune system) control the diseased organ/apparatus and in turn are influenced by a feedback mechanism. In this article, we will consider the psycho-neuroendocrine-immune approach to coloproctological disorders, by providing clinical cases and discussing them in light of this approach.

Anorectal incontinence: a challenge in diagnostic and therapeutic approach

Anorectal incontinence is a symptom of a complex multifactorial disorder involving the pelvic floor and anorectum, which is a severe disability and a major social problem. Various causes may affect the anatomical and functional integrity of the pelvic floor and anorectum, leading to the anorectal continence disorder and incontinence. The most common cause of anorectal incontinence is injury of the sphincter muscles following delivery or anorectal surgeries. Although the exact incidence of anorectal incontinence is unknown, various studies suggest that it affects ~2.2-8.3% of adults, with a significant prevalence in the elderly (>50%). The successful treatment of anorectal incontinence depends on the accurate diagnosis of its cause. This can be achieved by a thorough assessment of patients. The management of incontinent patients involves conservative therapeutic procedures, surgical techniques, and minimally invasive approaches.

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.

[Descending perineum in women]

Physiopathological and clinical interpretation of the descending perineum as described by A. Parks in 1970 remains difficult. This review is based on the literature between 1966 and 2004. The observed symptoms are more often due to associated lesions. The descending perineum on X-ray is not always symptomatic. Colpocystography shows the descent of the perineum and pelvic disorders from the anterior and middle parts of the perineum whereas defecography seems to provide a better diagnosis of dyschesia due to posterior damage (such as rectocele or endo-anal intussusception). The first step of treatment is reeducation and medical treatment because there is no consensus for surgical therapy. Soft sacrocolpopexy by the abdominal approach with three meshes, one under the bladder, one in front of and one behind the rectum can be proposed for complete descending perineum. Transanal rectal resection by staple could be useful when the descending perineum is only associated with a rectocele and/or an intra-anal intussusception.

Anal sphincter injury in women with pelvic floor disorders

OBJECTIVE

1) To estimate the rate of anal incontinence and anal sphincter injury in a group of women with pelvic floor disorders; 2) to evaluate the relationship between anal incontinence and anal sphincter injury as demonstrated by endoanal ultrasonography; 3) to explore any associations between operative vaginal delivery and anal sphincter injury in this population.

METHODS

A cohort of 100 women with stage II or greater pelvic organ prolapse and/or urinary incontinence completed the Rockwood-Thompson Fecal Incontinence Severity Index Questionnaire (FISI). Pelvic organ prolapse was recorded using the Pelvic Organ Prolapse Quantification system. Multichannel cystometry and endoanal ultrasonography were performed. Categorical data were compared using the chi(2) statistic. The FISI scores were correlated with degree of anal sphincter injury using the Pearson correlation coefficient (r).

RESULTS

Fifteen women with pelvic organ prolapse only, 28 with urinary incontinence only, and 57 with both were evaluated. Mean age (+/- standard deviation) and body mass index were 57.1 +/- 13.2 years and 29.8 +/- 6.8 kg/m(2), respectively. Median parity was 3. Fifty-four percent of those studied had anal incontinence, and 52% had anal sphincter defects. Anal incontinence was significantly associated with sphincter injury (odds ratio 36.4, 95% confidence interval 12-114, P <.001). The FISI scores were positively correlated with increasing degrees of anal sphincter disruption (r = 0.81, P <.001). A history of operative vaginal delivery was significantly associated with anal sphincter injury (P =.023).

CONCLUSION

Anal incontinence and anal sphincter injury are common in women with other pelvic floor disorders and are significantly related. Operative vaginal delivery may contribute to unrecognized anal sphincter trauma in this population.

LEVEL OF EVIDENCE

III

Frequency of anal incontinence and results of pelvic viscerography in 291 women with pelvic organ prolapse

OBJECTIVES

To determine the prevalence of anal incontinence in a population of 291 women with pelvic organ prolapse and evaluate the results of pelvic viscerogram in this situation.

MATERIALS AND METHODS

Each patient answered a standardized questionnaire on medical, obstetric and surgical past histories and answers were logged in a database. The viscerograms were performed by a single specialized radiologist.

RESULTS

All patients but one were parous. The prevalence of anal incontinence was 26.1%. Stress urinary incontinence and urge urinary incontinence were significantly associated with anal incontinence. No obstetric or surgical risk factor for anal incontinence was demonstrated. Viscerography demonstrated rectoceles (n=86, 29.1%), enteroceles (n=77, 26.5%), cystoceles (n=174, 59.8%), and intra-anal rectal prolapse (n=106, 36.4%). A significant association was found between intra-anal rectal prolapse and anal incontinence.

CONCLUSION

Anal incontinence is frequent in patients with pelvic organ prolapse, even more so in the presence of urinary incontinence, and should be investigated by pelvic viscerography. Pelvic floor dysfunction is frequently associated with enteroceles, rectoceles and rectal prolapse. Pelvic viscerograms should be systematically performed in the diagnostic work-up in patients with pelvic organ prolapse when surgical treatment is considered.

Prevalence and severity of urinary incontinence and pelvic genital prolapse in females with anal incontinence or rectal prolapse

PURPOSE

The aim of this study was to determine the prevalence, severity, and associations between urinary incontinence and genital prolapse in females after surgery for fecal incontinence or rectal prolapse.

METHODS

All patients who underwent surgery for fecal incontinence (Group I) or rectal prolapse (Group II) were compared with a control group of females (Group III) by 43 questions regarding demographic data, past medical and surgical history, and diagnosis and treatment of anal and urinary incontinence and genital and rectal prolapse. The type (stress, urge, and total) of urinary incontinence was determined and graded using an incontinence severity questionnaire (Individual Incontinence Impact Questionnaire).

RESULTS

Overall response rate in the three groups of patients was 40.1 percent. The questionnaire was sent to 240 patients operated on for fecal incontinence or rectal prolapse, and 83 of them responded (34.5 percent). The patients were distributed into three groups: Group I consisted of 51 patients (mean age 56.7 +/- 14); Group II consisted of 32 patients (69.7 +/- 11); and Group III consisted of 40 patients (60.5 +/- 16). The prevalence of urinary incontinence in Group I was 27 (54 percent), in Group II was 21 (65.6 percent), and Group III was 12 patients (30 percent; P = 0.003). Genital prolapse was present in 9 (17.6 percent), 11 (34.3 percent), and 5 patients (12.5 percent), respectively (P = 0.03). The prevalence of coexistent urinary incontinence and genital prolapse in both study groups was 22.8 percent (19 patients). There were no statistically significant differences between Groups I and II relative to prevalence, type, and severity of urinary incontinence and genital prolapse, but there were significant differences between the two study groups and the control group. Of the patients in the study group, 67 percent had urinary incontinence before or at the time of surgery.

CONCLUSION

There is a higher prevalence and severity of urinary incontinence and pelvic genital prolapse in females operated on for either fecal incontinence or rectal prolapse than in a control group. Therefore, female patients with fecal incontinence or rectal prolapse should be evaluated and treated by a multidisciplinary group of pelvic floor clinicians, including a gynecologist or urologist with special training in female pelvic floor dysfunction and a colorectal surgeon.

Follow-up evaluation of the effect of vaginal delivery on the pelvic floor

PURPOSE

The aim of this study was to evaluate the effect of vaginal delivery on the pelvic floor by serial measurement of pudendal nerve terminal motor latency, perineal descent, and anal pressure before and after delivery.

METHODS

Eighty pregnant females (40 primigravidae, 40 multigravidae) expecting vaginal delivery were prospectively evaluated. Measurements of pudendal nerve terminal motor latency, perineometry, and manometry were performed two to three months before delivery and two to three days, two months, and six months after delivery.

RESULTS

Before delivery, pudendal nerve terminal motor latency showed no significant difference between primigravidae and multigravidae. Perineal plane at straining was lower and the descent was larger in multigravidae than primigravidae. Anal squeeze pressure was also lower in multigravidae than primigravidae. Two to three days after delivery, regardless of the group, pudendal nerve terminal motor latency was prolonged, perineal plane at straining became lower, the descent increased, and anal squeeze pressure decreased. Two months after delivery, pudendal nerve terminal motor latency recovered to the level before delivery. Perineal descent also recovered somewhat, but remained increased after six months had passed. In primiparae, perineal plane at straining remained lower after six months had passed. However, in multiparae the plane remained lower only for two months and recovered by six months postpartum. Anal squeeze pressure also showed a moderate recovery, but still remained significantly lower at six months postpartum.

CONCLUSIONS

Pudendal nerve damage and functional impairment in the pelvic floor sphincter musculature occurs during vaginal delivery. Pudendal nerve terminal motor latency recovers after two months, whereas functional disturbance in the pelvic floor persists at least until six months.

AGA technical review on anorectal testing techniques

This literature review and the recommendations therein were prepared for the American Gastroenterological Association Clinical Practice and Practice Economics Committee. Following external review, the paper was approved by the committee on May 17, 1998.

Fecal incontinence in women

Pelvic floor disorders are common in women. Most gynecologists are well versed in the management of urinary incontinence and uterovaginal prolapse; however, knowledge of disorders involving the anorectum is often lacking. This review will discuss the issue of anorectal incontinence in women, attempt to provide a logical outline for evaluation and treatment, and offer potential methods of prevention.

Pathophysiology of pelvic organ prolapse

Pelvic organ prolapse is usually caused by weakness of the pelvic diaphragm. Descent of the pelvic diaphragm places stress on the endopelvic connective tissue support system. Subsequent increases in intra-abdominal pressure result in prolapse. In the majority of cases, labor and childbirth are thought to be the primary factors responsible for pelvic neuropathies and tissue damage that predispose to the development of POP. Certain connective tissue defects, congenital defects, and operative procedures also contribute to pelvic support defects.

The clinical evaluation of pelvic floor dysfunction

Although Baden concluded that "the pelvic exam is just the pelvic exam," the history and examination are tools of no less merit than the cystometrogram or scalpel for clinicians treating patients with symptomatic pelvic floor dysfunction. An effective history and physical examination provide the basis for effective management of the patient's symptoms.

A clinical approach to fecal incontinence

Fecal incontinence is the impaired ability to control gas or stool. It is a disabling and distressing condition. Its exact incidence and prevalence are unknown. It is a disorder about which patients are frequently reluctant to discuss, even with their physician. However, it is a common condition especially in older individuals, where the prevalence has been reported to approach 60%. In women, incontinence reaches 54% as a result of childbirth. Of the patients surgically treated, the female-to-male ratio is 4 to 1. In an epidemiological study to identify its community-based prevalence, the University of Illinois determined fecal incontinence existed in 2.2% of the general population. There is available treatment for fecal incontinence. Many patients improve with conservative treatment (constipating agents, antidiarrheal medications, dietary changes) or with biofeedback. For patients where conservative treatment has failed, surgical treatment (direct-apposition sphincter repair, overlapping sphincteroplasty, postanal repair, neosphincter procedures) may be successful.

A case of idiopathic fecal incontinence. Evaluation and management

Idiopathic fecal incontinence is a clinical entity described mostly in the colorectal surgical literature and seldom encountered by the physiatrist. Evidence exists suggesting neuropathic injury to the external anal sphincter. Several reports have linked this syndrome to the descending perineum syndrome. A final answer to this diagnostic puzzle is yet to be found. This article presents a case of probable "idiopathic" fecal incontinence presenting during an evaluation for low back pain. Full evaluation yielded a denervating lesion of unknown etiology to the pudendal nerve. The patient was managed with a bowel program without success. Because physiatrists often find themselves managing cases of neurogenic bowel or bladder, it is important for the physiatrist to have a thorough understanding of idiopathic fecal incontinence. A discussion of the differential diagnosis and management of fecal incontinence is included.

Age and anorectal sensibility in normal women

BACKGROUND

Our aim was to study associations between age and anorectal sensibility in healthy women.

METHODS

Seventy-five women, with a mean age of 50 (range, 20-83) years, and mean parity of 2 (range, 0-4), were studied. Anal mucosa electrosensitivity (AME) was measured 1 and 2 cm from the anal verge. Rectal sensibility was also measured (minimum perceived volume (MPV), desire to defaecate (DD), and urgency (U)). Associations between anorectal sensibility and age were corrected for parity by using multiple regression analysis.

RESULTS

Threshold values of AME increased with age (P = 0.03) (1 cm) and P = 0.01 (2 cm)). Rectal sensibility threshold values were also positively associated with age (MPV, P = 0.003; DD, P = 0.04; and U, P = 0.06). Changes in AME were greater after menopause, whereas associations between rectal sensibility and age seemed linear.

CONCLUSION

Impairment of the anorectal sensibility appears to be part of the normal ageing process, thus increasing the risk of faecal incontinence in old women.

Test-retest repeatability of anorectal physiology tests in healthy volunteers

PURPOSE

This study was undertaken to evaluate repeatability of tests of anorectal function in 58 healthy female volunteers, mean age 50 (range, 45-57) years.

METHODS

Participants were studied on two separate occasions by one investigator in one laboratory using the same equipment.

RESULTS

Mean difference for perineal position was 0.1 (95 percent confidence interval, -0.1-0.3) cm, and for perineal descent it was 0.02 (-0.2-0.3) cm. For anal mucosa electrosensitivity, mean difference was -0.1 (-0.4-0.1) mA, for maximum anal resting pressure it was 2.2 (-3.5-7.8) cm H2O, for maximum anal squeeze pressure it was -1 (-6.5-4.5) cm H2O, and for pudendal nerve terminal motor latency it was 0.04 (-0.02-0.09) msec. Coefficients of variation varied from 8 percent for pudendal nerve terminal motor latency to 49 percent for perineal descent.

CONCLUSION

There was no systematic variation in repeated measurements for any of the parameters studied; however, the nonsystematic variation was generally large.

Electrodiagnostic evaluation of fecal incontinence

The aim of this study was to assess the utility of electrodiagnostic testing (EDT) for the evaluation of fecal incontinence (FI). Over a 5-year period, 225 patients (174 females) with FI were prospectively studied with anal manometry, anal ultrasonography, anal electromyography (AEMG), and pudendal nerve terminal motor latency (PNTML) assessment. The mean age was 60 (range 12-94) years. Causes of FI identified by clinical evaluation were obstetric injuries (45), rectal prolapse (43), iatrogenic or other trauma (42), neurologic disease (23), and idiopathic (72). EDT revealed abnormalities in 76% of patients. The incidence of pudendal neuropathy (PN) was 36% (bilateral 21%, unilateral 15%). Patients with PN were older than were those with normal PNTML (mean 71 vs. 63 years; P < 0.002). No relationship between squeeze pressure and PN could be demonstrated (P = 0.9). Reduced motor unit potential (MUP) recruitment on AEMG was present in 60% and was associated with decreased squeeze pressure (P < 0.001) and increased MUP polyphasia (P < 0.001). Concurrence of AEMG and anal ultrasonographic findings was observed in 35 of 41 patients (84%). Defects were overlooked in one study but identified by the other on three occasions, each. Moreover, 8 of 22 patients with demonstrated sphincter defects had unsuspected PN or extensive sphincter injury on AEMG that precluded sphincter repair. In conclusion, EDT proved to be a valuable tool in the evaluation and subsequent treatment of patients with FI.

What is the relationship between perineal descent and anal mucosal electrosensitivity?

PURPOSE

Perineal descent is found in many patients with anorectal disorders. There is now substantial evidence against perineal descent causing damage to the motor axons in the pudendal nerves, but the sensory sequelae of perineal descent have been neglected. The purpose of this study was to establish the relationship between perineal descent and anal sensation.

METHODS

Perineal position was determined in relation to the bony pelvis by means of defecating proctography. Anal mucosal electrosensitivity was determined by using a constant current generator.

RESULTS

This study demonstrated significant correlations between perineal position at rest and sensitivity in each third of the anal canal in the study group overall. In women studied alone, there were significant correlations between perineal position at rest and at squeeze and anal mucosal electrosensitivity in each third of the anal canal.

CONCLUSIONS

We propose that perineal descent traumatizes the pudendal nerves, damaging the large diameter sensory axons. This may be a precursor of motor axon damage or may correlate with the global pelvic sensory loss found in patients with perineal descent and fecal incontinence.

Striated anal sphincter electromyography in idiopathic fecal incontinence

PURPOSE

This study was designed to determine the importance of innervation of striated anal sphincters, one of the most important structures in idiopathic fecal incontinence.

METHODS

Forty-three idiopathic, fecally incontinent patients (40 women and 3 men; mean age, 57.2 +/- 11 (range, 33-77) years) underwent anorectal manometry and sphincteric electromyography. On the basis of electromyographic findings, patients were subdivided into three groups: Group A consisted of 21 patients with normal electromyography; Group B consisted of 14 patients with moderate denervation; Group C consisted of 8 patients with severe denervation. Manometric results from the patients were compared with those from 15 healthy subjects (8 women and 7 men; mean age, 35 +/- 12 (range, 15-55) years).

RESULTS

Incontinent patients had a shorter anal canal (P = 0.005), and anal canal pressure was lower at rest (P < 0.001), at contraction (P < 0.001), and at coughing (P < 0.001); rectal distention and rectal compliance were reduced (maximum tolerated volume, P < 0.003; compliance at 200 ml, P = 0.03; at 250, P < 0.005; at 300 ml, P = 0.03). No statistically significant differences were found between the manometric results of the three different groups of patients. A statistically significant linear correlation was reached by comparing the clinical severity of fecal incontinence with age (P = 0.02) and some other manometric parameters: the pressure of the anal canal at rest (P < 0.001) and at contraction (P < 0.01); rectal compliance at 50 ml (P = 0.03), 100 ml (P = 0.004), and 150 ml (P = 0.004).

CONCLUSION

Clinical severity of fecal incontinence is correlated with some manometric parameters. Severity of denervation of the anal striated sphincters does not appear to influence severity of fecal incontinence.

Surgical anatomy of the pudendal nerve and its clinical implications

A study of the surgical anatomy of the pudendal nerve (PN) was performed in 13 female and 7 male cadavers. The knowledge of the precise anatomy and anomalies of this important nerve would help in better localization of the nerve and its roots and branches for neurostimulation or for pudendal canal decompression in pudendal canal syndrome. Two routes were used in the dissection: gluteal and perineal. The PN was identified and its course was followed from its roots to its termination. The PN was composed of three roots derived from the 2nd, 3rd, and 4th anterior sacral rami (S 2,3,4). The roots received a contribution from S 1 in five cadavers and from S 5 in one. The three roots formed two cords. The first root continued as the upper cord while the second and third root fused together producing the lower cord. The PN was formed by union of the two cords a short distance proximal to the sacrospinous ligament, and then crossed the back of the ligament. In no specimen did the nerve cross the ischial spine. The inferior rectal nerve arose from the PN in the pudendal canal in 18 cadavers. In two cases it came out proximal to the canal; this would spare the two subjects the anorectal manifestations of the pudendal canal syndrome. As the PN crossed the back of the sacrospinous ligament, it gave origin to a branch that supplied the levator ani muscle. This branch was only found in male cadavers and we call it "accessory rectal nerve"; the levator ani muscle in such cadavers was doubly innervated on its perineal aspect.

Fecal incontinence

Fecal incontinence is a common but infrequently reported, imperfectly understood, multifactorial disease with far-reaching socioeconomic and psychological implications. Limited success with somewhat empirical surgical procedures implies that patients should be investigated fully, indications for surgery should be clear, and disability should be serious enough to demand surgical intervention. Dietary adjustments and medical treatment should be tried first. Unwelcome though it is, colostomy may be the ultimate remedy in some patients.

Significance of the thickness of the anal sphincters with age and its relevance in faecal incontinence

BACKGROUND

Ultrasonographic studies in healthy volunteers showed that the external anal sphincter (EAS) and internal anal sphincter (IAS) thicknesses were inversely related at rest. The functional importance of the two sphincters in continence control was demonstrated in the relationship between the sum of the thicknesses of the two sphincters and the anal canal resting pressure. The aims of the present study were to assess the morphometric appearance of the anal sphincters by endosonography in faecally incontinent patients and to contrast this with that of older healthy subjects.

METHODS

Twenty-eight female patients with neurogenic faecal incontinence (FI) were studied. An older group of 7 healthy women, aged 41-75 years, and a young group of 11 nulliparous healthy women, aged 20-23 years, served as control groups. Anal endosonography was performed with a radial rotating endoprobe, with the subject in the left lateral position. Conventional anal manometry was performed in all subjects.

RESULTS

The EAS in the FI group was thicker than the EAS in the old (p < 0.04) but did not differ from the EAS in the young. The IAS thickness in the FI group did not differ from that in the older group. In both these groups the IAS was thicker than in the young women (p < 0.01). The anal pressures in the FI group were reduced compared with the normal groups (p < 0.04). There was a direct relationship between the two sphincters in FI (p < 0.001).

CONCLUSIONS

The increased thickness of the IAS in the FI group does not seem to compensate for function and results in a failure of the sphincter mechanism to maintain continence, whereas in healthy elderly subjects the increased IAS thickness appears to be compensatory and important for continence control.

Evidence of electromechanical dissociation of the internal anal sphincter in idiopathic fecal incontinence

PURPOSE

This study was designed to evaluate the relationship between internal sphincter electromyographic frequency and ambulatory anal pressures in order to clarify the pathophysiology of internal anal sphincter dysfunction in fecal incontinence.

METHODS

Seventy-two patients of median age 55 years (range, 24-75; 63 females) with neurogenic fecal incontinence and 33 normal subjects of median age 48.5 years (range, 25-74; 21 females) underwent fine-wire anal sphincter electromyography and anal manometry.

RESULTS

The median internal anal sphincter electromyographic frequency was incontinent 0.25 Hz (0.2-0.34) and the control was 0.44 Hz (0.36-0.55; P < 0.03). Ambulatory resting pressures were incontinent median 54 cm of H2O (34-68 cm of H2O) and control 94 cm of H2O (72-102; P < 0.01). Internal sphincter electromyographic frequency correlated with anal resting pressures in both groups (P < 0.002). Internal sphincter electromyographic silence not attributable to electrode movement or the rectoanal inhibitory reflex, lasting 0.5 to 4 minutes occurred in all but two of the incontinent patients. The anal pressure during this period did not significantly change (P > 0.1). No recruitment of the external sphincter or puborectalis was noted during these episodes. Such electromechanical dissociation was not seen in the control group. The frequency of transient internal sphincter relaxation was 4 (ranges 2-6) per hour in controls and 8 (ranges, 6-12) per hour in incontinent patients (P < 0.01). Rectal pressures did not exceed midanal pressures in any of the controls but did in all of the incontinent patients on at least one occasion per hour in the incontinent group.

CONCLUSION

Internal anal sphincter activity exhibits electromechanical dissociation and relaxes abnormally in incontinent patients.

The acute effect of straining on pelvic floor neurological function

Integrity of sensory and motor function is essential in the maintenance of continence. The pudendal nerve assumes a central role being a mixed sensory and motor nerve. Neuropathic changes may therefore lead to incontinence and stretch injury to the pudendal nerve has been implicated as an aetiological factor. However pudendal neuropathy, altered anal sensation and perineal descent do not always correlate in the same patient. To investigate this further we evaluated the effect of a simulated defaecation strain on pelvic floor neurological function in a group of patients with constipation and incontinence. Pudendal nerve terminal motor latency (PNTML) and anal electrosensitivity (AS) were measured at rest and after a simulated defaecation strain of 1 minute. At rest PNTML correlated with AS (r = 0.461, P = 0.003). Twenty-five patients had perineal descent of more than 1 cm on straining, and 13 had descent below the ischial tuberosities. After 1 minute of straining AS was significantly (P < 0.001) blunted and PNTML was significantly (P < 0.001) prolonged both changes returning to normal after 3 minutes. AS was significantly (P = 0.01) more blunted in patients with perineal descent of more than 1 cm. PNTML was significantly (P = 0.01) more prolonged in patients with perineal descent of more than 2 cm. Age was significantly correlated with AS (r = 0.45, P = 0.004) and PNTML (r = 0.49, P = 0.002). Anal sensation and PNTML are acutely affected by defaecation straining, and changes may occur in patients without perineal descent. Functional changes occur equally in constipated and incontinent patients.

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.

Anal endosonography in healthy subjects and patients with idiopathic fecal incontinence

PURPOSE

This study investigates the normal ultrasonographic morphology of pelvic floor striated muscle and evaluates whether there are differences between males and females and between healthy subjects and patients with idiopathic fecal incontinence.

METHODS

Manometric and ultrasonographic studies of the anal canal were performed in 30 healthy volunteers and in 26 patients with idiopathic fecal incontinence. Verification of ultrasonographic findings was obtained by studying anatomic preparations.

RESULTS

Ultrasonography reliably identified the internal and external anal sphincter and frequently visualized neighboring structures. In addition, it detected muscular structures that have not clearly been described previously. However, differences in external sphincter function between males and females and between healthy subjects and incontinent patients were not reflected by alterations in muscle thickness.

CONCLUSIONS

Endosonography of the anal canal clearly delineates muscular structures and may even visualize structures that have been previously incompletely defined. However, it remains to be shown that differences in certain muscular functions have a morphologic correlate that can be detected by endosonography.

Does perineal descent correlate with pudendal neuropathy?

A prospective study was undertaken to assess the potential correlation between increased perineal descent (IPD) and pudendal neuropathy (PN) in 213 consecutive patients. These 165 females and 48 males of a mean age of 62 (range, 18-87) years had constipation (n = 115), idiopathic fecal incontinence (n = 58), or chronic intractable rectal pain (n = 40). All 213 patients underwent cinedefecography (CD) and bilateral pudendal nerve terminal motor latency (PNTML) assessment. Perineal descent (PD) of more than the upper limit of normal of 3.0 cm during evacuation was considered increased. Pudendal neuropathy was diagnosed when PNTML exceeded the upper limit of normal of 2.2 milliseconds. Although 65 patients (31 percent) had PD, only 16 (25 percent) of these 65 patients had neuropathy. Moreover, PN was also found in 42 (28 percent) of 148 patients without IPD. Conversely, only 16 (28 percent) of the 58 patients who had PN also had IPD, and IPD was present in 49 (32 percent) of 155 patients without PN. The frequency of PN according to the degree of IPD was: 3.0 to 4.0 cm, 6 of 27 patients (22 percent); 4.1 to 5.0 cm, 4 of 15 (27 percent); 5.1 to 6.0 cm, 4 of 12 (25 percent); 6.1 to 7.0 cm, 2 of 8 (25 percent); and > 7.0 cm, 0 of 3 (0 percent). Linear regression analysis was undertaken to compare the relationships between measurements of PD at rest (R), push (P), and change (C = P-R) and values of PNTML. These values for all 213 patients were: R, r = 0.048; P, r = 0.031; and C, r = -0.050. The correlation coefficients were equally poor for all the individual subgroups analyzed, including the patient's sex or diagnosis. In summary, no correlation was found between PD and PNTML. The lack of a relationship was seen for the entire group as well as for those patients with either neuropathy or increased perineal descent. Therefore, the often espoused relationship between increased PD and PN was not supported by this prospective evaluation. Although increased PD and prolonged PNTML are frequently observed in patients with disordered defecation, they may represent independent findings.

Internal anal sphincter dysfunction in neurogenic faecal incontinence

Forty-eight patients of median age 57 years with neurogenic faecal incontinence and 44 normal subjects of median age 51 years underwent fine-wire anal sphincter electromyography and anal manometry. The median (interquartile range (i.q.r.)) internal anal sphincter (IAS) electromyogram frequency was 0.26 (0.21-0.32) Hz for patients with faecal incontinence and 0.44 (0.31-0.55) Hz for controls (P < 0.01). The median (i.q.r.) ambulatory resting pressure was 48 (34-68) cmH2O for patients and 86 (72-102) cmH2O for controls (P < 0.01) and median (i.q.r.) frequency of transient IAS relaxations 9 (7-12) and 4 (3-7) per h respectively (P < 0.05). Mid-anal pressure fell to a greater extent in patients with incontinence during these episodes of transient IAS relaxation. Rectal pressure during such relaxation did not exceed mid-anal canal pressure in controls; for the patient group, rectal pressure increased during relaxation and exceeded mid-anal canal pressure in 36 cases. Frequent abnormal episodes of IAS relaxation may cause occult faecal leakage in patients with neurogenic faecal incontinence.

Abnormal visceral autonomic innervation in neurogenic faecal incontinence

Changes of denervation in the anal sphincter striated and smooth muscle in patients with neurogenic faecal incontinence are well established. This study aimed to determine if there is also a more proximal visceral autonomic abnormality. Thirty women with purely neurogenic faecal incontinence (prolonged pudendal nerve latencies and an intact sphincter ring) and 12 patients with neuropathic changes together with an anatomical disruption were studied. Two control groups consisted of 18 healthy volunteer women and 17 women with normal innervation but an anatomically disrupted sphincter. Rectal sensation was assessed using balloon distension and electrical mucosal stimulation, and anal sensation by electrical stimulation. Rectal compliance was studied to determine whether sensory changes were primary or caused by altered rectal wall viscoelastic properties. Anal canal pressure changes in response to both rectal distension and rectal electrical stimulation were measured to assess the intrinsic innervation of the internal anal sphincter. Patients with neurogenic incontinence alone had impaired rectal sensation to distension (53.1 v 31.5 ml, p < 0.05, neurogenic v controls) and to electrical stimulation (24.4 v 14.8 mA, p < 0.005). Patients with neurogenic incontinence and sphincter disruption also showed impaired sensation compared with healthy controls (55.8 ml v 31.5 ml, p < 0.05 and 22.9 mA v 14.8 mA, p < 0.05). Patients with only a disrupted sphincter had normal visceral sensation to both types of testing. Both rectal compliance and the response of the internal anal sphincter to rectal distension and electrical stimulation were normal in all patient groups. This study suggests that there is a visceral sensory abnormality in patients with neurogenic incontinence which is not caused by altered rectal compliance. As evaluated in this study the intrinsic innervation of the internal anal sphincter is not affected in this process.

Etiology and management of fecal incontinence

Fecal incontinence is a challenging condition of diverse etiology and devastating psychosocial impact. Multiple mechanisms may be involved in its pathophysiology, such as altered stool consistency and delivery of contents to the rectum, abnormal rectal capacity or compliance, decreased anorectal sensation, and pelvic floor or anal sphincter dysfunction. A detailed clinical history and physical examination are essential. Anorectal manometry, pudendal nerve latency studies, and electromyography are part of the standard primary evaluation. The evaluation of idiopathic fecal incontinence may require tests such as cinedefecography, spinal latencies, and anal mucosal electrosensitivity. These tests permit both objective assessment and focused therapy. Appropriate treatment options include biofeedback and sphincteroplasty. Biofeedback has resulted in 90 percent reduction in episodes of incontinence in over 60 percent of patients. Overlapping anterior sphincteroplasty has been associated with good to excellent results in 70 to 90 percent of patients. The common denominator between the medical and surgical treatment groups is the necessity of pretreatment physiologic assessment. It is the results of these tests that permit optimal therapeutic assignment. For example, pudendal nerve terminal motor latencies (PNTML) are the most important predictor factor of functional outcome. However, even the most experienced examiner's digit cannot assess PNTML. In the absence of pudendal neuropathy, sphincteroplasty is an excellent option. If neuropathy exists, however, then postanal or total pelvic floor repair remain viable surgical options for the treatment of idiopathic fecal incontinence. In the absence of an adequate sphincter muscle, encirclement procedures using synthetic materials or muscle transfer techniques might be considered. Implantation of a stimulating electrode into the gracilis neosphincter and artificial sphincter implantation are other valid alternatives. The final therapeutic option is fecal diversion. This article reviews the current status of the etiology and incidence of incontinence as well as the evaluation and treatment of this disabling condition.

Electromyography of the pubococcygeus muscles in patients with obstructed defaecation

The function of the pubococcygeus muscles during defaecation straining was compared in 10 women with obstructed defaecation and 12 age-matched control subjects. Video-proctography in each patient showed failure to evacuate the rectum and sagging of the pelvic floor during attempted defaecation. Trans-perineal concentric needle electromyography in the puborectalis muscle and transvaginal electromyography in the pubococcygeus muscle was carried out during defaecation straining and during attempted rectal balloon expulsion. Contraction of the pubococcygeus muscle was observed in 10 of the 12 control subjects and in 2 of the 10 patients with obstructed defaecation (P < 0.005). Virtually equal proportions of subjects in each group showed relaxation or contraction of the puborectalis muscle during straining. There was significant perineal descent on straining in the patient group (P = 0.005). This group of patients with obstructed defaecation showed failure of the pubococcygeus muscles to contract, perhaps due to neuropathic weakness of the muscles. The puborectalis muscle did not cause obstructed defaecation in these patients, and the concept of "paradoxical" contraction of this muscle is questioned.

Are pelvic floor movements abnormal in disordered defecation?

Pelvic floor movements were assessed by videoproctography in 126 subjects: neuropathic fecal incontinence patients (n = 44), chronic constipation patients (n = 52), and controls (n = 30). A significantly lower pelvic floor position at rest and a more obtuse anorectal angle were found in incontinent patients than in controls (P less than 0.01). Constipated patients showed no significant difference from controls at rest. There was less pelvic floor movement during contraction in incontinent patients than in controls, indicating a flaccid, noncontractile pelvic floor in neuropathic incontinence. Movement during contraction in constipated subjects was also less than in controls. Changes in the pelvic floor position during straining were the same as in controls. These data indicate that the pelvic floor is flaccid and noncontractile in neuropathic fecal incontinence, which supports the concept of a progressive neuropathy involving the sacral outflow. Similar changes are not seen at rest in patients with constipation even though they have a long history of straining.

External anal sphincter function in spinal patients. Electromyographic and manometric study

Six patients with complete transection of the spinal cord and six healthy volunteers were examined by using anorectal manometry together with electromyographic (EMG) recording of the external anal sphincter composed of striated muscle. Anal pressure and EMG activity of the external anal sphincter were continuously recorded at rest and during gradual rectal distention (10, 20, 30, 40, and 50 ml) by means of an air-filled balloon eliciting a rectoanal inhibitory reflex (RAIR) at the upper part, and an inflation reflex (IR) at the lower part of the anal canal. All patients and controls had a RAIR for each rectal distention volume. A relationship between the duration of the RAIR and the rectal distention volume was present in controls only. In controls the IR was present for each rectal distention volume, whereas it was present in only one patient for a 40-ml volume. During the resting period, all controls showed continuous tonic EMG activity of the external anal sphincter, but after 30 minutes all the patients showed a decrease and ultimately in five cases a disappearance of the tonic EMG activity of the external anal sphincter. In spinal patients, the presence or absence of EMG activity of the external anal sphincter did not modify the anal canal pressure. These results indicate that: 1) the tonic EMG activity of the external anal sphincter seems to be under the control of supraspinal structures, because in spinal patients it disappears in the absence of sensitive inputs toward the spinal cord; 2) the absence of EMG activity at rest indicates that the external anal sphincter is not implicated in the RAIR disturbances observed in spinal patients; 3) the IR is not a spinal reflex but is under voluntary control, because it is not present in spinal humans; 4) in spinal humans the tonic EMG activity of the external anal sphincter does not play a role in the maintenance of the anal pressure at rest.

Anal endosonography in the investigation of faecal incontinence

Forty-four consecutive patients with incontinence of solid stool of traumatic or idiopathic aetiology were examined by anal endosonography and standard anorectal physiology tests. Anal endosonography showed an external anal sphincter defect in four out of 11 (36 per cent) patients with idiopathic (neurogenic) incontinence. In the remaining seven patients both parts of the sphincter were intact and a linear relationship was found between the resting anal canal pressure and the endosonographic thickness of the internal anal sphincter. Twenty-eight out of 33 (85 per cent) patients with incontinence of traumatic origin had external sphincter defects, confirmed by concentric needle electromyogram mapping in the 19 patients in whom this was performed. Eleven of these 28 (39 per cent) patients also had disruption of the internal sphincter. Anal endosonography has revealed significant abnormalities in patients with faecal incontinence and has a complementary role to anorectal physiology in the routine investigation of these patients.

Pudendal nerve function in women with symptomatic utero-vaginal prolapse

Pelvic floor function has been studied in 27 women with symptomatic utero-vaginal prolapse and 15 age-matched control subjects. There was no evidence in the patients on physiological testing of significant denervation of the pelvic floor muscles, with no significant difference in the maximum resting and squeeze anal pressures, the pudendal nerve terminal motor latency or external anal sphincter fibre density on single fibre electromyography between the groups. However, those patients with a small rectocele (less than 2 cm) had a significantly higher fibre density than the group with a large rectocele (p = 0.03) and the control group (p less than 0.001). Six of eight patients with a small rectocele had increased fibre density compared with 3/19 with a large rectocele (p = 0.006) and 2/15 control subjects (p = 0.006). This was independent of age, obstetric factors and the presence of internal rectal prolapse. These findings suggest that patients with symptomatic utero-vaginal prolapse and small rectoceles have pelvic nerve damage, and development of a large rectocele may provide some protection against perineal descent and pudendal neuropathy, although the number of patients in the small rectocele group was small and confirmation from further similar studies is required.

Results of surgery in idiopathic faecal incontinence

The surgical treatment of idiopathic faecal incontinence remains a difficult problem particularly in those cases where advanced neuropathy is present. The physiological basis for the post-anal repair have now been questioned and the long term functional results seem to be rather unsatisfactory. Pelvic floor repair is a more comprehensive approach with encouraging initial results which need to be assessed in a long term experiment and in a prospective randomised comparison with conventional post-anal repair. Gracilis transposition in idiopathic faecal incontinence has shown very disappointing results and has probably no role in the treatment of this condition. Intestinal stoma in very advanced cases may occasionally provide important hygienic and psychological benefit.