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

The relationship between residual sphincter damage after primary repair, faecal incontinence, and anal sphincter function in primiparous women with an obstetric anal sphincter injury

BACKGROUND AND AIMS

Anal sphincter injury has been identified as a primary cause of post-partum fecal incontinence in women with obstetric anal sphincter injury. However, women without obstetric anal sphincter injury may also develop fecal incontinence. The aim is to determine the relationship between fecal incontinence severity; and i) residual anal sphincter injury, quantified by the Starck score, and ii) anal sphincter tone.

METHODS

Consecutive case series of prospectively collected data set in a Pelvic Floor Unit within a tertiary teaching hospital in Australia. Population 181 primiparous women with Sultan classification Grade 3 and 4 sphincter injuries.

MAIN OUTCOME MEASURES

Sultan classification, anal manometry, pudendal nerve terminal motor latency, St Mark's fecal incontinence score, and Starck ultrasound score.

RESULTS

45% of women reported some degree of fecal incontinence. One third of women with normal external sphincter tone were incontinent. Those with higher Starck score had higher St Mark's scores. A higher Sultan classification correlated with more severe incontinence regardless if the repair was complete. Forceps delivery had a twofold risk of incontinence when compared to non-forceps delivery.

CONCLUSION

The importance of an effective anal sphincter repair is confirmed. However, overall there is no direct relationship between residual sphincter damage, anal sphincter tone, and fecal incontinence severity. These data indicate that anal sphincter integrity alone is not the sole mechanism for maintaining fecal continence. Rectal and colonic motor function may also play a role and investigation into these components may provide greater insight into the effect of vaginal delivery upon fecal continence mechanisms.

Impedance planimetric description of normal rectoanal motility in humans

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Functional oesophago-gastric junction imaging

Despite its role in disease there is still no definitive method to assess oesophago-gastric junction competence (OGJ). Traditionally the OGJ has been assessed using manometry with lower oesophageal sphincter pressure as the indicator. More recently this has been shown not to be a very reliable marker of sphincter function and competence against reflux. Disorders such as gastro-oesophageal reflux disease and to a lesser extend achalasia still effects a significant number of patients. This review looks at using a new technique known as impedance planimetry to profile the geometry and pressure in the OGJ during distension of a bag. The data gathered can be reconstructed into a dynamic representation of OGJ action. This has been shown to provide a useful representation of the OGJ and to show changes to the competence of the OGJ in terms of compliance and distensibility as a result of endoluminal therapy.

Mechanisms controlling normal defecation and the potential effects of spinal cord injury

Spinal cord injury frequently leads to bowel dysfunction with the result that emptying the bowel can occupy a significant part of the day and reduce the quality of life. This chapter contains an overview of the function and morphology of the normal distal gut in the human, and of gut behaviour in normal defecation. In humans, this can be monitored and is described, but knowledge of the mechanisms controlling it is limited. Work on animals has shown that the intrinsic activity of the smooth muscles and their interactions with the enteric nervous system can program the activity that is necessary to expel waste material, but the external anal sphincter is controlled through somatic nerves. The gut however also receives input from the central nervous system through autonomic nerves, and a spinal reflex centre exists. Voluntary effort to induce defecation can influence all the control mechanisms, but the precise importance of each is not understood. The behaviour and properties of the individual muscles in the normal human rectum and anal canal are described, including their responses to intrinsic nerve stimulation and adrenergic and cholinergic agonists. The effects of established spinal cord injury are then considered. For convenience, supraconal and conal/cauda equina lesions are considered as two categories. Prolongation of transit times and disordered defecation are common problems. Supraconal lesions result in reduced resting anal pressures and increased risk of fecal incontinence. The acute effects of spinal cord injury are described, with injury causing ileus (prolonged total gastrointestinal transit times), constipation (prolonged colonic transit times) and fecal incontinence (passive leakage).

Faecal incontinence in patients with anal fissure: a consequence of internal sphincterotomy or a feature of the condition?

BACKGROUND AND OBJECTIVE

The function of the internal sphincter is disturbed in patients with chronic anal fissure due to persistent hypertonia and it may lead to a certain degree of incontinence. Our aim is to assess the results of lateral internal sphincterotomy and to identify any degree of incontinence related to the disease.

METHODS

This prospective study included a review of all patients operated upon by the authors who performed division of the internal sphincter at or below the upper limit of the fissure. A questionnaire was completed by each patient before surgery and then after surgery with regard to any degree of incontinence such as soiling of underclothes, control of flatus and accidental bowel motion.

RESULTS

126 patients with chronic anal fissure were studied. The male to female ratio was 0.8:1. Minor degrees of incontinence were present prior to surgery in 35 patients (28%) and in 31 (25%) patients after surgery, the majority of them were incontinent before surgery.

CONCLUSION

Based on the results of this study, minor degrees of incontinence could be a symptom of chronic anal fissure and not the sequelae of lateral internal sphincterotomy.

Anorectal dysfunction increases with time following radiation therapy for carcinoma of the prostate

OBJECTIVES

To characterize the prevalence and pathophysiology of anorectal dysfunction up to 2 yr following radiation therapy (RT) for localized carcinoma of the prostate.

METHODS

Thirty-eight patients, median age 68 (range 60-82) yr with localized prostate carcinoma randomly assigned to one of two radiation dose schedules, underwent evaluation of the following variables of anorectal function before RT, as well as 4-6 wk and 1 and 2 yr after its completion: (1) symptoms, (2) anorectal motility, (3) anorectal sensory function, and (4) anal sphincteric morphology.

RESULTS

There was a persistent increase in anorectal symptoms after RT. At 2 yr, bowel frequency, urgency, and fecal incontinence were increased in 50%, 47%, and 26% of patients, respectively. After RT, there were progressive reductions of (1) basal anal pressures, (2) anal pressures in response to squeeze and increased intra-abdominal pressure, (3) rectal compliance, and (4) rectal volumes associated with sensory perception and the desire to defecate. The thickness of the external anal sphincter increased with time after RT. No difference was observed between the patients in the two radiation dose schedules.

CONCLUSIONS

Anorectal dysfunction following RT for prostate carcinoma is an underestimated cause of morbidity, which progresses with time. The prevalence and pathophysiology of anorectal dysfunction is similar after treatment with two commonly used radiation dose schedules.

Anal pressure waves in patients with irritable bowel syndrome

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Internal anal sphincter: advances and insights

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

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.

Physiology and pathophysiology of anal function

A review of the Danish contributions to the increased understanding of anorectal physiology and pathophysiology during the last 25 years is presented. In this period there has been a vast international increase in interest in anorectal physiology and pathophysiology, with much improvement in the understanding and treatment of anorectal functional disorders. The application of new sophisticated techniques to anorectal physiology research continues to improve our knowledge of anorectal function.