Rationale for medical or surgical therapy in anal incontinence

Rectal Hyposensitivity Is Associated With a Defecatory Disorder But Not Delayed Colon Transit Time in a Functional Constipation Population

The physiological mechanism of functional constipation (FC) includes defecatory disorders and delayed colon transit. About 18% to 68% constipated patients may have rectal hyposensitivity (RH). We performed this study to investigate the association between RH and functional defecatory disorder (FDD) as well as that between RH and delayed colon transit in FC patients.A total of 218 FC patients were enrolled. The constipation severity instrument (CSI) was used to assess constipation symptoms. High-resolution anorectal manometry (HR-ARM), defecography, balloon expulsion tests, and colon transit studies were performed for each patient. RH was defined as 1 or more sensory threshold pressures raised beyond the normal range based on HR-ARM. We investigated the association between RH and constipation symptoms, and the occurrence of FDD and delayed CTT. Ninety FDD patients completed the initial phase of biofeedback treatment (BFT). We investigated the association between RH and the effect of BFT.Totally 122 (56.0%) patients had RH. The total CSI (49.82 ± 1.09 vs 41.25 ± 1.55, P = 0.023) and obstructive defecation subscale scores (23.19 ± 0.69 vs 17.07 ± 0.90, P < 0.001) were significantly higher in RH than in non-RH patients. No significant difference was observed in slow transit symptoms (21.77 ± 0.72 vs 19.90 ± 0.85, P = 0.121) or abdominal pain (6.85 ± 2.61 vs 5.00 ± 1.04, P = 0.380). The frequency of prolonged CTT was not significantly different between RH and non-RH groups (54.1% vs 58.3%, P = 0.403). RH patients rated more occurrence of FDD (72.1% vs 53.1%, P = 0.014) and dysynergic defecation (79.8% vs 50.2%, P = 0.004) than non-RH patients, whereas no differences were seen for inadequate defecatory propulsion (59.2% vs 55.0%, P = 0.589). After BFT, the proportion of "no effect" was significantly higher in the RH group than in the non-RH group (22.4% vs 9.4%, P = 0.010).RH is associated with obstructive defecation symptoms and the occurrence of FDD. Further studies are needed to detect the mechanism of RH's effect on BFT and FC.

Effect of biofeedback therapy in constipation according to rectal sensation

BACKGROUND/AIMS

The pathophysiologic mechanism of rectal hyposensitivity (RH) is not well documented, and the significance of RH in biofeedback therapy (BFT) has not been evaluated. Thus, we aimed to assess the effect of BFT in constipated patients according to the presence of RH.

METHODS

Five hundred and ninety constipated patients (238 males and 352 females) underwent anorectal physiologic assessments. Of these, anorectal manometry was performed before and after BFT in 244 patients (63 RH and 181 non-RH patients).

RESULTS

The success rate of BFT was 56% in the RH and 61% in the non-RH group (p=0.604). The measurements of resting pressure, squeezing pressure, desire to defecate volume, urge to defecate volume, and maximum volume were decreased after BFT in the RH group (p<0.05), whereas only resting and squeezing pressures were decreased in the non-RH group (p<0.05). Among the RH group, individuals who responded to BFT showed decreased resting pressure, squeezing pressure, desire to defecate, urge to defecate, and maximum volume and increased balloon expulsion rate; among those who did not respond to BFT, only desire to defecate volume was improved.

CONCLUSIONS

In constipated patients with RH, changes of anorectal manometric findings differed in comparison to patients without RH. The responses to BFT showed both anorectal muscle relaxation and restoration of rectal sensation.

Rectal hyposensitivity: pathophysiological mechanisms

Rectal hyposensitivity (RH) relates to a diminished perception of rectal distension. It may occur due to afferent nerve dysfunction and/or secondary to abnormal structural or biomechanical properties of the rectum. The aim of this study was to determine the contribution of these underlying pathophysiological mechanisms by systematically evaluating rectal diameter, compliance and afferent nerve sensitivity in patients with RH, using methodology employed in clinical practice. The study population comprised 45 (33 women; median age 48, range 25-72 years) constipated patients (Rome II criteria) with RH and 20 with normal rectal sensitivity on balloon distension and 20 healthy volunteers. Rectal diameter was measured at minimum distending pressure during isobaric distension under fluoroscopic screening. Rectal compliance was assessed during phasic isobaric distension by measuring the slope of the pressure-volume curve. Electrical stimulation of the rectal mucosa was employed to determine afferent nerve function. Values were compared to normal ranges established in healthy volunteers. The upper limits of normal for rectal diameter, compliance and electrosensitivity were 6.3 cm, 17.9 mL mmHg(-1) and 21.3 mA respectively. Among patients with RH, rectal diameter, but not compliance, was increased above the normal range (megarectum) in seven patients (16%), two of whom had elevated electrosensitivity thresholds. Rectal diameter and compliance were elevated in 23 patients (51%), nine of whom had elevated electrosensitivity thresholds. The remaining 15 patients (33%) with RH had normal rectal compliance and diameter, all of whom had elevated electrosensitivity thresholds. Two-third of the patients with RH on simple balloon distension have elevated rectal compliance and/or diameter, suggesting that impaired perception of rectal distension is due to inadequate stimulation of the rectal afferent pathway. However, a proportion of such patients also appear to have impaired nerve function. In the remaining one-third of the patients, rectal diameter and compliance are normal, while electrosensitivity thresholds are elevated, suggestive of true impaired afferent nerve function. Identification of these subgroups of patients with RH may have implications regarding their management.

Rectal hyposensitivity

Rectal hyposensitivity (RH) relates to a diminished perception of rectal distension that is diagnosed during anorectal physiologic investigation. There have been few direct studies of this physiologic abnormality, and its contribution to the development of functional bowel disorders has been relatively neglected. However, it appears to be common in patients with such disorders, being most prevalent in patients with functional constipation with or without fecal incontinence. Indeed, it may be important in the etiology of symptoms in certain patients, given that it is the only "apparent" identifiable abnormality on physiologic testing. Currently, it is usually diagnosed on the basis of elevated sensory threshold volumes during balloon distension in clinical practice, although such a diagnosis may be susceptible to misinterpretation in the presence of altered rectal wall properties, and thus it is uncertain whether a diagnosis of RH reflects true impairment of afferent nerve function. Furthermore, the etiology of RH is unclear, although there is limited evidence to support the role of pelvic nerve injury and abnormal toilet behavior. The optimum treatment of patients with RH is yet to be established. The majority are managed symptomatically, although "sensory-retraining biofeedback" appears to be the most effective treatment, at least in the short term, and is associated with objective improvement in the rectal sensory function. Currently, fundamental questions relating to the contribution of this physiologic abnormality to the development of functional bowel disorders remain unanswered. Acknowledgment of the potential importance of RH is thus required by clinicians and researchers to determine its relevance.

Clinical and physiological findings, and possible aetiological factors of rectal hyposensitivity

BACKGROUND

Rectal hyposensitivity (RH) relates to insensitivity of the rectum on anorectal physiological investigation and appears common in functional bowel disorders. The clinical significance of this physiological abnormality is unclear.

METHOD

RH was defined as one or more sensory threshold volumes raised beyond the normal range (mean plus two standard deviations) on rectal balloon distension. Clinical information and results of other anorectal physiological investigations were evaluated in 261 patients with RH.

RESULTS

Patients with RH most commonly presented with constipation (48 per cent), constipation and incontinence in combination (27 per cent), or faecal incontinence (20 per cent). Thirty-eight per cent of patients had a history of previous pelvic surgery, 22 per cent a history of anal surgery and 13 per cent a history of spinal trauma. In patients with RH presenting with symptoms of constipation or incontinence, impaired rectal sensation was the only abnormality on physiological investigation in 48 per cent and 31 per cent respectively.

CONCLUSION

Patients with RH display marked heterogeneity in terms of presenting symptoms. The exact causes of RH are unknown, but there is evidence to suggest that pelvic nerve injury and spinal trauma are possible aetiological factors. RH appears important in the aetiology of both constipation and faecal incontinence, and may be useful as a predictor of surgical outcome.

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.

Anal sphincter repair: a report of 60 cases and review of the literature

This is a retrospective review of 58 patients undergoing surgery for anal incontinence at the Cleveland Clinic. Forty-four patients had overlapping sphincter repairs, nine had postanal repairs, three had a combination of overlapping repair and postanal repair and two had Silastic slings. An associated loop colostomy or ileostomy was performed in 19 patients (33%). Satisfactory continence was attained in 86% of patients with direct sphincter injury (overlapping sphincter repairs) and this is comparable with the experience of others. These results with the postanal repair for patients with neurogenic incontinence were poor, however, as four of the nine were complete failures. Poor results were directly related to the age of the patient (P less than 0.0001) and the duration of incontinence (P less than 0.02). It was concluded that direct sphincter injury (obstetric, operative or traumatic) is effectively treated by an overlapping sphincter repair. Incontinence secondary to a degenerative neuropathy affecting the anal sphincter mechanism, however, whether it occurs in conjunction with a pre-existing sphincter injury or alone, is often not cured by surgery, that is, by postanal repair.

Impaired rectal sensation in idiopathic faecal incontinence

In 15 patients suffering from idiopathic faecal incontinence and in 15 matched controls, manometric studies of anorectal pressure and studies of the rectoanal reflex and rectal sensitivity were carried out. Patients with idiopathic faecal incontinence had normal resting pressure but reduced squeeze and stress pressures; the anal sphincter relaxed before a sensation of rectal distension occurred. The conclusion is that both reduced voluntary muscle contraction and impairment of rectal sensation are conducive to soiling in idiopathic faecal incontinence.