Anorectal profilometry with the microtransducer

Traditional measures of normal anal sphincter function using high-resolution anorectal manometry (HRAM) in 115 healthy volunteers

BACKGROUND

High-resolution anorectal manometry (HRAM) is a relatively new method for collection and interpretation of data relevant to sphincteric function, and for the first time allows a global appreciation of the anorectum as a functional unit. Historically, traditional anal manometry has been plagued by lack of standardization and healthy volunteer data of variable quality. The aims of this study were: (i) to obtain normative data sets for traditional measures of anorectal function using HRAM in healthy subjects and; (ii) to qualitatively describe novel physiological phenomena, which may be of future relevance when this method is applied to patients.

METHODS

115 healthy subjects (96 female) underwent HRAM using a 10 channel, 12F solid-state catheter. Measurements were performed during rest, squeeze, cough, and simulated defecation (push). Data were displayed as color contour plots and analysed using a commercially available manometric system (Solar GI HRM v9.1, Medical Measurement Systems). Associations between age, gender and parity were subsequently explored.

KEY RESULTS

HRAM color contour plots provided clear delineation of the high-pressure zone within the anal canal and showed recruitment during maneuvers that altered intra-anal pressures. Automated analysis produced quantitative data, which have been presented on the basis of gender and parity due to the effect of these covariates on some sphincter functions. In line with traditional manometry, some age and gender differences were seen. Males had a greater functional anal canal length and anal pressures during the cough maneuver. Parity in females was associated with reduced squeeze increments.

CONCLUSIONS & INFERENCES

The study provides a large healthy volunteer dataset and parameters of traditional measures of anorectal function. A number of novel phenomena are appreciated, the significance of which will require further analysis and comparisons with patient populations.

Posterior sagittal anorectoplasty in anorectal anomalies: clinical, manometric and profilometric evaluation

CONTEXT AND OBJECTIVE

Anorectal malformations comprise a spectrum of anomalies that continue to be difficult to treat, even today. The aim was to evaluate the fecal continence of children who underwent posterior sagittal anorectoplasty due to anorectal malformations, via computerized anorectal manometry and profilometry.

DESIGN AND SETTING

Prospective study at Universidade Federal de São Paulo.

METHOD

82 patients (56.1% boys; 43.9% girls) of mean age 85.5 months were evaluated. They were divided into continent, partially continent and incontinent groups. Age, sex, manometric variables and profilometric parameters were studied. The results were statistically analyzed.

RESULTS

Among the 82 patients, 37.8% were continent, 25.6% were partially continent and 36.6% were incontinent. The overall mean resting pressure was 22 mmHg, and the means for the continent, partially continent and incontinent groups were, respectively, 30.7 mmHg, 23 mmHg and 14.7 mmHg. The overall mean pressure response to voluntary contraction was 56 mmHg, and the means for the groups were 65.4 mmHg, 55.8 mmHg and 46.6 mmHg, respectively. The rectosphincteric reflex was absent in 82.9% of the cases. In the profilometry analysis for all patients together, blue (20 to 50 mmHg) and yellow (50 to 80 mmHg) were predominant, and there was a similar distribution for the continent and partially continent patients. However, among the incontinent patients, green (< 20 mmHg) and blue prevailed.

CONCLUSIONS

Manometric and computerized profilometric analyses were an excellent method for postoperative evaluations on patients with intermediate and high anorectal anomalies, and for therapeutic planning.

The relationship of pudendal nerve terminal motor latency to squeeze pressure in patients with idiopathic fecal incontinence

PURPOSE

With the advent of transanal ultrasonography it has been possible to identify those incontinent patients without sphincter defects. The majority of these patients are now thought to have neurogenic fecal incontinence secondary to pudendal neuropathy. They have been found to have reduced anal sphincter pressures and increased pudendal nerve terminal motor latencies. The aim of this study was to determine whether in those incontinent patients who do not have a sphincter defect, prolonged pudendal nerve terminal motor latency correlates with anal manometry, in particular maximum squeeze pressure.

METHODS

Sixty-six incontinent patients were studied with transanal ultrasonography, anorectal manometry, and pudendal nerve terminal motor latency. Twenty-seven continent controls had anorectal manometry and pudendal nerve terminal motor latency measured.

RESULTS

Maximum resting pressure and maximum squeeze pressure were significantly lower in the group of incontinent patients with bilateral prolonged pudendal nerve terminal motor latency (median maximum resting pressure = 26.5 mmHg; median maximum squeeze pressure = 60 mmHg) when compared with incontinent patients with normal bilateral pudendal nerve terminal motor latencies (median maximum resting pressure = 46 mmHg; median maximum squeeze pressure = 79 mmHg; maximum resting pressure P = 0.004; and maximum squeeze pressure P = 0.04). In incontinent patients with no sphincter defects no correlation between pudendal nerve terminal motor latency and maximum squeeze pressure was found (r = -0.109, P = 0.48) and maximum squeeze pressure did not correlate with bilateral or unilateral prolonged pudendal nerve terminal motor latency (r = -0.148, P = 0.56 and r = 0.355, P = 0.19 respectively).

CONCLUSIONS

In patients with idiopathic fecal incontinence damage to the pelvic floor is more complex than damage to the pudendal nerve alone. Although increased pudendal nerve terminal motor latency may indicate that neuropathy is present, in patients with neuropathic fecal incontinence, pudendal nerve terminal motor latency does not correlate with maximum squeeze pressure. Normal pudendal nerve terminal motor latency does not exclude weakness of the pelvic floor.

Manometric tests of anorectal function in healthy adults

OBJECTIVE

Although tests of anorectal function are useful in the assessment of defecation disorders, there is inadequate and inconsistent information regarding normative data. Also, there are discrepancies in manometric techniques and data interpretation. Our aim was to perform a comprehensive evaluation of anorectal function in healthy adults.

METHODS

We used a 6-mm diameter probe containing six radially arrayed microtransducers, and a 4-cm-long latex balloon for performing anorectal manometry in 45 healthy subjects who were controlled for gender and age. Sequentially, subjects were asked to squeeze, bear down, or blow up a party balloon. Subsequently, rectal sensation, rectal compliance, and rectoanal reflexes were assessed simultaneously by performing intermittent phasic balloon distentions. Additionally, balloon defecation, pudendal nerve latency, and saline continence tests were performed.

RESULTS

In men, the anal sphincter was longer (p < 0.05) and squeeze sphincter pressure and squeeze duration were higher (p < 0.01), but resting sphincter pressure was similar to that in women. When bearing down, although not significant, the defecation index was higher in men. Distinct thresholds for rectal sensation were identified but there was no gender difference. Likewise, rectal compliance and balloon expulsion time were similar. However, during saline infusion, the onset of first leak and total volume retained were higher (p < 0.001) and pudendal nerve latency was shorter (p < 0.05) in men. Overall, parity or age did not influence anorectal function.

CONCLUSIONS

This study represents the most comprehensive age- and gender-controlled assessment of anorectal function using solid state technology. Gender influences some parameters of anorectal function. Our results could serve as a valuable resource of normative data.

The Favre system for anorectal manometry: comparison with other manometry systems in vitro and in healthy volunteers

BACKGROUND

The Favre system operates with airflow in a semi-closed circuit to transmit pressure. We aimed to evaluate the Favre system in comparison with other commonly used manometry systems.

METHODS

The Favre, Arndorfer, Arhan, and Synectics systems were evaluated in vitro and in 14 volunteers.

RESULTS

In vitro testing showed no relevant differences for latency, precision, or retest stability. In vivo, maximum resting pressure differed among all probes (P < 0.01) except for Arhan versus Arndorfer (NS). Maximum squeeze pressures differed among all probes (P < 0.01). Decrease of resting pressure during rectoanal inhibitory reflex was similar for Favre versus Arndorfer and Arhan versus Synectics (NS). Retest stability was higher with Favre than with Arndorfer (P < 0.05) and Synectics (P < 0.05) with regard to maximum resting pressure; it was higher with Favre than with Arhan (P < 0.01) and Arndorfer (P < 0.05) with regard to maximum squeeze pressure. Favre caused less discomfort than Synectics (P < 0.05) or Arndorfer (P < 0.05).

CONCLUSION

The Favre probe is an excellent and cost-efficient system for routine anorectal manometry.

Are special investigations of value in the management of patients with fecal incontinence?

PURPOSE

The aim of this study was to determine whether special investigations significantly alter either the diagnosis or the management plan of patients with fecal incontinence assessed on the basis of a structured history and physical examination alone.

METHODS

Fifty consecutive patients with fecal incontinence were prospectively studied in a tertiary referral clinic. Each patient was assessed by two clinicians who independently formulated a diagnosis and treatment plan based on the history and physical examination. The resulting 100 patient assessments were then compared with the final diagnosis and treatment plan formulated on completion of endoanal ultrasound, anal manometry, external sphincter electromyography, and defecating proctography.

RESULTS

In the assessment of fecal incontinence, the addition of special investigations altered the diagnosis of the cause of incontinence based on history and examination alone in 19 percent of cases. The management plan was altered in 16 percent of cases. Special investigations were most useful in separating neuropathy from rectal wall disorders and in demonstrating the unexpected presence of internal sphincter defects and neuropathy.

CONCLUSIONS

Even experienced colorectal surgeons will misdiagnose up to one-fifth of patients presenting with fecal incontinence if assessment is based on the history and physical examination alone. However surgically correctable causes of incontinence are rarely missed on clinical assessment.

Surgery for constipation: a review

PURPOSE

Constipation is related to intestinal motility disorders (colonic inertia (CI)), pelvic floor disturbances (pelvic outlet obstruction), or a combination of both problems. This review summarizes the physiologic and pathophysiologic changes in patients with intractable constipation and gives an overview of surgical treatment options.

RESULTS

Although subtotal colectomy with ileorectal anastomosis is the best surgery for CI, there are still approximately 10 percent of patients who will complain of pain and constipation. A completion proctectomy and an ileoanal pouch procedure may be a viable option in a highly select group of patients. In patients with megabowel, reported results are mixed. Subtotal colectomy, partial colectomy for megacolon, and the Duhamel procedure for megarectum have all been reported with variable results. In patients with an isolated distended sigmoid colon, sigmoid colectomy has achieved good results. Anorectal myectomy has not been proven to be successful in the long term. However, in patients with adult short segment Hirschsprung's disease, myectomy can be successful. Patients with pelvic outlet obstruction can be successfully treated with biofeedback. In a small group of patients with a rectocele or a third degree sigmoidocele, surgical intervention yields a high success rate. Division or resection of the puborectalis muscle is not recommended. In patients with a mixed pattern of CI and pelvic outlet obstruction, surgical intervention alone is often not successful. These patients achieve better results by conservative treatment of pelvic outlet obstruction, followed by a colectomy.

CONCLUSION

Surgical intervention for patients with intractable constipation is rarely necessary. However, thorough preoperative physiologic testing is mandatory for a successful outcome.

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.

A regional audit of the investigation and treatment of colorectal and pelvic floor disorders (1984-1991)

The activities of a regional physiology unit established for the investigation of colorectal and pelvic floor physiology in health and disease in a clinically relevant setting has been audited and its evolution described over a period of eight years. Trends in surgical treatment of some of these disorders over the same period have also been documented in the Lothian Region. Although there has been little change in the number of patients investigated annually patterns of investigation appear to change. Sphincter manometry, proctometrography and somatosensory reflex measurements have remained the most frequently performed and useful investigations. Spinal stimulation studies increased transiently because of a collaborative investigation of bowel and bladder function in patients with spinal injuries. A considerable increase in surface EMG tests and dynamic proctography has occurred. These trends are thought to be related to interest in defining evacuation dysfunction of the rectum and related problems of the pelvic floor. Isotope proctography now rivals barium videoproctography; at the same time the use of manometric colonic motility studies has diminished. Anal ultrasonography has replaced sphincter mapping in the last year and is being applied to other aspects of anorectal pathology. The last 4 years have seen the introduction and increasing use of non-surgical therapeutic modalities for the treatment of faecal incontinence and constipation: reflex electronic sphincter stimulation, biofeedback and the use of a prokinetic agent to promote colonic motility. Concomitant changes in the surgery of constipation and reconstructive anorectal procedures have been observed. It is recommended that coloproctology units should have easy access to at least one such investigation laboratory within their catchment area together with appropriate auditing facilities.

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.

Autonomic influences on colorectal motility and pelvic surgery

The nervous control of the motility of the human distal bowel was investigated by two physiological studies of electrical stimulation of sacral parasympathetic outflow in patients with high spinal injuries and in patients with intractable constipation following pelvic surgery. Identical and reproducible motility responses of the left colon, rectum, and anal sphincters were obtained by sequential electrical stimulation of anterior sacral roots S2, S3, and S4 in patients with spinal injury. S2 stimulation provoked isolated low-pressure colorectal contractions. S3 stimulation initiated frequency-dependent high-pressure colorectal motor activity which appeared peristaltic and was enhanced with repetitive stimuli. S4 stimulation increased colonic and rectal tone. Quantitative responses were maximal at the splenic flexure and rectum. Pelvic floor activity was stimulated in increasing magnitude from S2 to S4. These results of distal bowel motility were achieved by an implanted Brindley stimulator. A newer generation of externally active stimulators are envisaged for the control of lower bowel in fecal incontinence. Women with intractable constipation following hysterectomy had significantly increased rectal volume and compliance together with deficits of rectal sensory function. Following stimulation with Prostigmine (neostigmine) a colorectal motility gradient was paradoxically reversed in the patients following hysterectomy, thus constituting a functional obstruction. Denervation supersensitivity was demonstrable in 2 patients tested with carbachol provocation. These findings suggest dysfunction in the autonomic innervation of the hindgut in some patients following hysterectomy.

Solitary rectal ulcer: the place of biofeedback and surgery in the treatment of the syndrome

Thirty-one patients with the solitary rectal ulcer syndrome were studied, the majority of whom presented with fresh blood per rectum and a rectal ulcer, mucorrhoea, or a varying degree of rectal prolapse. Fourteen patients were treated conservatively or with surgery and had a high rate of recurrence of the solitary rectal ulcer syndrome. Seventeen patients were treated with biofeedback for the associated obstructed defecation (anismus) either before or immediately after surgery with a lower recurrence rate. The final symptomatic cure rate was similar in both groups but 15 episodes of recurrence requiring further surgery were encountered in the non-biofeedback group compared to 4 recurrences in the biofeedback group.

The results of pouch surgery after ileo-anal anastomosis for inflammatory bowel disease: the manometric assessment of pouch continence and its reservoir function

Anal sphincter function after restorative proctocolectomy has mainly been investigated by anal manometry. A significant decrease of basal pressure up to 45%, has been recorded postoperatively, possibly due to sphincter stretch during endoanal mucosectomy. Both abdominal mucosectomy and anastomosis at the level of the anorectal ring have been reported to prevent anal sphincter damage and lead to better continence. The striated sphincter is not significantly affected by the surgical procedure. Pouch-anal inhibitory reflex is partly maintained in the presence of a rectal cuff which leaves the ganglionic plexus unaltered; a satisfactory continence is also retained in the absence of the reflex when the rectum is totally excised. Pouch capacity, compliance and motility have been investigated by endoluminal balloon and probes. Pouch emptying has been studied by a "porridge" test, by a semi-solid medium labelled with technetium-99, and by other methods. A more effective storage function is achieved by large capacity reservoirs which lower the bowel frequency. The motor response to pouch distension, to a meal, and to pharmacological stimuli is usually counteracted by sphincter contraction. Ileal hypermotility may lead to fecal leakage mainly in the presence of weak sphincters. Poor pouch emptying may be related to an anal stricture.

Determination of X-ray-induced damage to the murine colon using tissue compliance measurements

A proctometroscope has been developed to measure the mechanical functioning of the colon in a murine model. A balloon-tipped probe is inserted into the colorectal region of anaesthetized mice and inflated hydraulically, at a constant rate, by a motor-driven syringe. Balloon pressure and volume are monitored, processed and plotted on a X-Y/t recorder. The balloon is inserted within the irradiated area, such that the centre of the balloon is 1 cm proximal to the anus, and inflated up to either a maximum volume of 100 microliters or a maximum pressure of 100 cmH2O, depending on which occurs first. Compliance (delta V/delta P) of the colon was measured at various intervals following X-irradiation, a dose-dependent decrease being observed at 24 weeks. This decrease was progressive with time out to 72 weeks postirradiation. The compliance measured, in both control and irradiated groups, was not dependent on the inflation rate used to make the determination, and no iatrogenic effects have been detected after repeated probing during a long-term study. The use of different anaesthetic agents was also investigated, no significant difference between the compliance of mice anaesthetized with the different agents being detected. Use of this technique provides fully quantitative data on the function of the colon following radiation injury, and provides an alternative to other physiological assays. The technique is non-destructive, rapid, easy to use and non-invasive to the tissue, thus the onset and progression of damage can be followed in each mouse over long postirradiation periods.

Disordered colorectal motility in intractable constipation following hysterectomy

Colorectal and anal sphincter motility and electrophysiology were investigated in 14 women with profound constipation following hysterectomy and compared with an asymptomatic group of control subjects. Twelve patients complained of significant urinary symptoms. No differences in the motor function of the anal sphincters were detectable. The latency of the pudendoanal reflex was unchanged after hysterectomy. Proctometrograms demonstrated significantly increased rectal volumes and compliance in the hysterectomy group together with deficits of rectal sensory function. In the basal state a significant proximal-to-distal sigmoid colon motility gradient existed only in the control group. Following stimulation with Prostigmin, this gradient was enhanced in the control group but paradoxically reversed in the hysterectomized patients, thus constituting a functional obstruction. Denervation supersensitivity was demonstrable in two patients tested with carbachol provocation but not in control subjects. These findings suggest dysfunction in the autonomic innervation of the hindgut in some patients who had undergone hysterectomy, resulting in severe constipation.

Transducer manometry and the effect of body position on anal canal pressures

Anal canal manometry is performed conventionally with balloons, sleeves, perfused or nonperfused open-tipped catheters, or with multiport probes. The authors constructed a new manometer with four transducers embedded in a probe (15 mm outside diameter) and oriented radially, 90 degrees apart. The transducer probe was validated in 27 healthy volunteers by comparing its performance to that of a standard four-port perfused manometer and then used to measure anal canal and rectal pressures in body positions more physiologic (standing, sitting) than that usually employed (left lateral) for such measurements. Both devices measured similar anal canal resting pressure in the left lateral position (mid canal, 58 +/- 3 mm Hg perfused vs. 62 +/- 4 mm Hg transducer; P greater than 0.05). The transducer probe, however, recorded higher squeeze pressures (mid canal, 100 +/- 6 mm Hg perfused vs. 143 +/- 14 mm Hg transducer; P less than 0.05). The transducer probe detected higher intrarectal and resting anal canal pressures when subjects were standing or sitting, compared with the left lateral position (rectum, 3 +/- 1 mm Hg left lateral; 17 +/- 2 mm Hg standing; 20 +/- 1 mm Hg sitting; P less than 0.05; mid anal canal, 57 +/- 3 mm Hg left lateral; 86 +/- 4 mm Hg standing; 81 +/- 5 mm Hg sitting, P less than 0.05). The rise in resting anal canal pressure was uniform circumferentially. Neither anal canal length nor squeeze pressure changed with change in position. The authors concluded that 1) transducer manometry recorded similar resting but higher squeeze pressures compared with perfused manometry; 2) transducer manometry recorded the same radial variation in anal canal resting and squeeze pressures as that recorded by the perfused manometer; and 3) standing and sitting caused a four-fold rise in intrarectal pressure, which was associated with a concomitant rise in resting anal canal pressure.

Anal manometry with microtransducer technique before and after restorative proctocolectomy. Sphincter function and clinical correlations

Anal manometry, with microtransducer technique, was performed in 55 patients after restorative proctocolectomy. Forty-two patients were followed regularly from before surgery until 12 months after surgery, and 23 patients until 24 months of function. Postoperatively, sphincter function was severely impaired. At 12 months, the mean height was less than 60 percent, mean area less than 50 percent, and mean length less than 90 percent of the preoperative values of the high pressure zone. There was no improvement between 12 and 24 months. Mean maximal squeeze pressure was restored at 12 months. Rectoanal inhibitory reflex was constantly present preoperatively, but in only 4 of 30 patients, postoperatively. Those patients with preoperative resting pressure 100 cm H2O or greater had significantly higher resting tones at 12 months than those with less than 100 cm H2O. Patients with 5 or fewer bowel movements every 24 hours had significantly higher resting tones than those with more than 6 movements every 24 hours (66 vs. 45 cm H2O). Patients with deferral 60 minutes or greater had significantly higher resting pressures than those with deferral less than 30 minutes (65 vs. 44 cm H2O). No correlation was found between resting pressure and state of continence.

A study of the physiological variation in anal manometry

The physiological variation in anal manometry using a perfused catheter with radiating sideholes was studied in 78 healthy volunteers. The maximum intraindividual variation in the length of the anal high pressure zone, resting pressure and squeeze pressure was 10 mm, 26 mmHg and 68 mmHg respectively. The median 95 per cent confidence interval for length of the pressure zone was 4 mm; for resting pressure it was 15 mmHg and for squeeze pressure it was 48 mmHg. Day-to-day variation did not exceed the intraindividual variation. Constant recording with the catheter fixed in the high pressure zone revealed slow waves and ultraslow waves with amplitudes of 6-24 mmHg which could account for most of the intraindividual variation. No sex difference was found in the length of the high pressure zone whereas resting pressure and squeeze pressure were higher in men than in women. Although a tendency towards a decrease in the length of the high pressure zone, resting pressure and squeeze pressure was observed with increasing age, no significant age-related difference could be demonstrated.

Neurophysiological abnormalities in genuine female stress urinary incontinence

Perineal sensory and motor function was investigated in 28 women with genuine stress incontinence of urine and compared with a matched control group. Electrosensitivity of the dorsal nerve of the clitoris and of the urethral mucosa was significantly diminished in these patients (eight measurements 'insensitive'). Three different reflex latency measurements (dorsal nerve to external anal sphincter, dorsal nerve to urethral sphincter, urethral mucosa to external anal sphincter) were prolonged in incontinence (14 absent reflexes). Mean motor unit potential duration of the external anal sphincter was also prolonged, reflecting an early neuropathy. Anorectal manometry detected significantly weaker squeeze pressures in stress incontinence although other variables were unaffected.

Neurophysiological dysfunction in young women with intractable constipation

Fifteen women with intractable chronic idiopathic constipation dating from adolescence were investigated by anorectal manometry, neurophysiological evaluation of the conus medullaris and external anal sphincter. Comparison was made with 25 asymptomatic female control subjects. Urological disturbances were common amongst the constipated, in five of whom incidental lumbosacral spinal dysraphism was found. No differences in sphincter pressures or the rectosphincteric reflex were demonstrable between the two groups. Rectal defecatory sensation was blunted and the compliance was increased in the constipated group. The latency of the pudendo-anal reflex was significantly prolonged in idiopathic constipation, two women having an absent reflex (greater than 100 ms). Mean motor unit potential duration of the external anal sphincter was not significantly prolonged in the eight constipated women tested. A central neurogenic deficit is postulated in some women with this disorder.

The action of cisapride on the chronic constipation of paraplegia

Paraplegic patients have intractable constipation associated with prolonged colonic transit time. The agent Cisapride significantly reduced the colonic transit time from 7.7 days to 5.1 days. It also improved the intraluminal tone in the rectum, resulting in a significant reduction in maximal rectal capacity from 305.8 ml to 224.3 ml. There was a reduction in residual urine volume from 51.5 ml to 27.7 ml. The increased number of stools containing transit markers showed that intraluminal mixing was increased by cisapride. Faecal water remained unchanged. A side effect was retention of urine in one subject after sudden withdrawal of the drug but this was avoided by its gradual reduction over 2 days.

Constipation in the elderly. A physiologic study

Colorectal motility was studied in 25 elderly patients with chronic constipation and compared with an asymptomatic control group (N = 17). Proctometrograms were performed to measure rectal volumes at sensory threshold and maximal tolerance, and rectal compliance. Anal sphincter pressures and reflexes were measured by conventional techniques. Indices of colonic motility were also assessed. Significant impairment of rectal sensory threshold was apparent in constipation. Six patients presenting with impaction demonstrated functional megarectums. The remaining 19 showed a significant reduction in maximal rectal volume and rectal compliance and 14 extruded the balloon. There were no differences in sphincter length or presence of the rectosphincteric reflex. Four patients had an absent pudendoanal reflex and the remainder significant prolongation. Total gastrointestinal transit times were prolonged in the constipation group, mainly distally due to rectal stasis. In two patients bisacodyl failed to elicit a sigmoid motor response. Constipation in the elderly is not merely due to delayed transit. Neurogenic deficits of sacral spinal cord function may be responsible for abnormalities in rectal motor and sensory function.

Assessment of microtransducers in anorectal manometry

It has been reported that microtransducer-tipped catheters (transducer) produce reliable reproducible measurements which correlate well with water-filled balloon systems. Maximum resting pressure (MRP) and maximum voluntary contraction pressures (MVC) were compared using a standard station pull-through technique in 12 patients. There was a poor correlation for both MRP: microballoon, 115 cmH2O (60-160 cmH2O); transducer 60 (20-110), r = 0.62, P less than 0.05, and MVC: microballoon, 202 (60-375); transducer, 175 (60-210), r = 0.42, n.s. To determine whether this was due to radial variation in pressures measured by the transducer, we studied a further 39 patients with both systems. At each station, transducer measurements were made at each of four quadrants. We found better correlation for MRP: microballoon, 100 (40-175); transducer, 66 (34-120), r = 0.72, P less than 0.001, and MVC: microballoon, 225 (55-650); transducer, 180 (50-470), r = 0.87, P less than 0.001, but a significant radial variation for the transducer where rotation reduced MRP pressure measurements by 21 per cent (0-600 per cent), and MVC 17 per cent (0-76 per cent). Moreover there was a significant difference between anterior and posterior MRP in the upper anal canal, anterior 35 (5-80) versus posterior 25 (10-60), P less than 0.05. These results account for the poor correlation between random positioning of the microtransducer-tipped catheter and indicate that radial orientation must be taken into account.

Electrophysiological observations on the human pudendo-anal reflex

A reproducible electrophysiological technique is described to determine the latency of reflex contraction of the external anal sphincter in response to stimulation of the dorsal genital nerve: the pudendo-anal reflex. This was studied in 38 asymptomatic control subjects and 20 women with neurogenic faecal incontinence, supplemented by determination of the mean motor unit potential duration (MUPD) of the external anal sphincter and anorectal manometry. The reflex latency in the control group was 38.5 +/- 5.8 (SD) ms and appeared to be independent of age or sex. Three patients with faecal incontinence had absent reflexes; the remainder showed significant prolongation of latency (56 +/- 12.2 SD ms) and diminution of amplitude. MUPD was prolonged in incontinence and showed significant correlation with the corresponding reflex latency determination (tau = 0.56, p less than 0.001). The latency of this polysynaptic spinal reflex hence provides a reliable index of neuropathy of the external anal sphincter.

Differential effects of sacral anterior root stimulation on anal sphincter and colorectal motility in spinally injured man

The motility responses of the sigmoid colon, rectum and external anal sphincter to sequential electrical stimulation of the anterior sacral roots (S2, S3 and S4) were studied in five patients with traumatic spinal cord injury. Identical and reproducible results were obtained. S2 stimulation provoked isolated low-pressure colorectal contractions. S3 stimulation initiated high-pressure colorectal motor activity which appeared peristaltic and was enhanced with repetitive stimuli. This response appeared to be frequency-dependent. S4 stimulation increased colonic and rectal tone. External sphincter activity was stimulated in increasing order from S2 to S4. These observations directly elucidate the central control of colorectal motility and may have implications in the treatment of severe constipation following spinal injury.

Anorectal function following colo-anal sleeve anastomosis for chronic radiation injury to the rectum

Anorectal manometry and electrophysiological studies of the pelvic floor were performed in eight patients who had undergone anterior resection of the rectum with mucosal proctectomy and colo-anal sleeve anastomosis for radiation rectal injury. There is a severe reduction in the compliance of the neorectum and in the maximal tolerable volume. Maximum basal anal canal pressure and physiological sphincter length are also significantly reduced although the 'squeeze' pressure of the external anal sphincter and the latency of the pudendo-anal reflex were unaffected. Four patients had an absent rectosphincteric reflex, four patients involuntarily expelled the test balloon at the maximal tolerable volume during a proctometrogram and four patients demonstrated increased EMG activity of the pelvic floor on straining and on rectal distension. These abnormalities help to explain many of the patients' symptoms. Histological abnormalities of the myenteric plexus were a prominent feature in all the excised specimens and may be responsible for some of the functional abnormalities.

Reproducibility of the proctometrogram

The reproducibility of a method of measuring rectal distensibility by continuous controlled fluid inflation with a balloon has been evaluated in 15 patients. The volume at sensation threshold, constant sensation and maximal tolerance, the pressures at these volumes and rectal compliance were measured. The mean coefficients of variation of the seven variables measured ranged from 4.7%-7.9%. The expected correlation between rectal compliance and maximal tolerable volume was confirmed (r = 0.85, p less than 0.001). The high reproducibility makes this investigation reliable for use in clinical practice and research.

Correlation of clinical and manometric abnormalities of rectal function following chronic radiation injury

Continuous fluid-inflation proctometrograms were performed in men with the symptoms of chronic radiation proctitis and in age and sex-matched control subjects (n = 10). Rectal volumes and compliance were measured. There was a significant reduction in the rectal volumes at sensory threshold, constant sensation and maximal tolerance and in rectal compliance (P less than 0.01). Comparable pressure measurements did not demonstrate significant differences. The maximum tolerable volume, symptomatic and sigmoidoscopic scoring correlated to rectal compliance (r = 0.77, -0.8, -0.73; P less than 0.01, less than 0.01, less than 0.02, respectively). Reduction in volume and compliance is often not obvious radiologically. Histological evidence suggests that smooth muscle hypertrophy and myenteric plexus damage are contributory.