Medium-term results of vertical reduction rectoplasty and sigmoid colectomy for idiopathic megarectum

Abnormal Perception of Urge to Defecate: An Important Pathophysiological Mechanism in Women With Chronic Constipation

INTRODUCTION

Although the association of absent or attenuated "call to stool" with constipation is well-recognized, no studies have systematically evaluated the perception of urge to defecate in a well-defined cohort of patients with chronic constipation (CC).

METHODS

A prospective study of 43 healthy adult women and 140 consecutive adult women attending a tertiary center for investigation of CC. All participants completed a 5-day viscerosensory questionnaire, and all women with CC also underwent anorectal physiologic investigations. Normal urge perception and abnormal urge perception were defined using a Naive Bayes model trained in healthy women (95% having normal urge).

RESULTS

In total, 181 toilet visits in healthy women and 595 in women with CC were analyzed. Abnormal urge perception occurred in 70 (50.0%) women with CC. In this group, the urge to defecate was more often experienced as abdominal sensation (69.3% vs 41.4%; P < 0.0001), and the viscerosensory referral area was 81% larger (median pixels anterior: 1,849 vs 1,022; P < 0.0001) compared to women with CC and normal urge perception. Abnormal (vs normal) urge in women with CC was associated with more severe constipation (Cleveland Clinic constipation score: 19 vs 15 P < 0.0001), irritable bowel syndrome (45.7% vs 22.9% P < 0.0001), and a functional evacuation disorder on defecography (31.3% vs 14.3% P = 0.023). A distinct pattern of abnormal urge was found in women with CC and rectal hyposensitivity.

DISCUSSION

Abnormal urge perception was observed in 50% of women with CC and was frequently described as abdominal sensation, supporting the concept that sensory dysfunction makes an important contribution to the pathophysiology of constipation.

Clinical Impact of Rectal Hyposensitivity: A Cross-Sectional Study of 2,876 Patients With Refractory Functional Constipation

INTRODUCTION

Normal bowel function requires intact sensory pathways. Diminished rectal sensation (rectal hyposensitivity [RH]) is associated with constipation, although its clinical importance remains unclear.

METHODS

Consecutive patients (aged 18-80) attending a tertiary center (2004-2016) for investigation of refractory functional constipation (Rome IV core criteria defined, applied post hoc) were included. Patients completed a clinical symptom questionnaire and underwent anorectal physiologic investigations, including rectal sensory testing (balloon distension) to determine 3 well-established sensory thresholds. Multivariate regression analyses were performed to evaluate associations between RH, symptomology, and allied physiologic investigations.

RESULTS

Of 2,876 patients meeting inclusion criteria, 722 (25%) had RH based on ≥1 elevated sensory thresholds (0: n = 2,154 [74.9%]; 1: n = 327 [11.4%]; 2: n = 209 [7.3%]; and 3: n = 186 [6.5%]). A linear relationship existed between increasing number of elevated sensory thresholds and constipation severity (Cleveland Clinic constipation score: mean difference per threshold [95% confidence interval] 0.69 [0.48-0.90]; P < 0.001). Several symptoms were significantly (P < 0.05) associated with RH including: infrequent defecation (odds ratio 1.29 [1.17-1.42]), painful evacuation (1.15 [1.05-1.27]), prolonged toileting (1.14 [1.05-1.24]), and digitation or enema use (1.18 [1.08-1.30]). On defecography, a "functional" evacuation disorder was also associated with RH (1.37 [1.25-1.50], P < 0.001), as was megarectum (2.52 [2.08-3.05], P < 0.001).

DISCUSSION

RH occurs in 25% of patients with refractory functional constipation. Increased number of elevated sensory thresholds is associated with more severe constipation phenotype. These data, in the largest study to date, provide for the first time evidence to show that RH is a major pathophysiologic mechanism in constipation, with recognized clinical impact (http://links.lww.com/AJG/B765).(Equation is included in full-text article.).

Rectal prolapse traumatizes rectal neuromuscular microstructure explaining persistent rectal dysfunction

PURPOSE

Internal rectal prolapse is common and correlates with age. It causes a plug-like physical obstruction and is a major cause of defecation disorder. The progressive distortion of the prolapsing rectum likely causes secondary defects in the rectal wall, which may exacerbate rectal dysfunction. We undertook a prospective observational study to detect and quantify the neurologic and histopathologic changes in the rectal wall.

METHODS

We examined dorsal and ventral rectal wall specimens from consecutive patients with internal rectal prolapse undergoing stapled transanal rectal resection (STARR). We subjected specimens to histopathologic and neuropathologic assessment, including immunohistochemistry. We also recorded patients' clinical and demographic characteristics and sought correlations between these and the pathologic findings.

RESULTS

We examined 100 specimens. The severity of rectal prolapse and the extent of descent of the perineum correlated significantly with age. Concomitant hemorrhoidal prolapse was noted in all male patients and in 79 % of female patients. Muscular and neuronal defects were detected in 94 and 90 % of the specimens, respectively. Only four specimens (4 %) were free of significant structural defects.

CONCLUSION

Rectal prolapse traumatizes the rectum causing neuromuscular defects. The tissue trauma is due to shearing forces and ischemia caused by the intussusception. This initiates a self-reinforcing vicious circle of physical and functional obstruction, further impairing rectal evacuation and causing constipation and incontinence. The correlation between extent of prolapse and age suggests that internal rectal prolapse can be considered a degenerative disorder. Neural and motor defects in the wall of the rectum caused by rectal prolapse are likely irreversible.

Rectal hyposensitivity

Impaired or blunted rectal sensation, termed rectal hyposensitivity (RH), which is defined clinically as elevated sensory thresholds to rectal balloon distension, is associated with disorders of hindgut function, characterised primarily by symptoms of constipation and fecal incontinence. However, its role in symptom generation and the pathogenetic mechanisms underlying the sensory dysfunction remain incompletely understood, although there is evidence that RH may be due to 'primary' disruption of the afferent pathway, 'secondary' to abnormal rectal biomechanics, or to both. Nevertheless, correction of RH by various interventions (behavioural, neuromodulation, surgical) is associated with, and may be responsible for, symptomatic improvement. This review provides a contemporary overview of RH, focusing on diagnosis, clinical associations, pathophysiology, and treatment paradigms.

Treatment of megacolon and megarectum

Patients presenting with megacolon and megarectum require extensive specialized testing to distinguish underlying Hirschsprung's disease from other secondary causes. Diagnostic testing and long-term treatment are best initiated after disimpaction has been achieved, by large-volume tap water enemas and/or oral colonic lavage with polyethylene glycol. With intensive treatment (including biofeedback if pelvic floor dysfunction is present), at lease one half of patients can avoid surgery. Maintenance therapy relies on daily use of osmotic laxatives. Stimulant laxatives are used intermittently as rescue treatments if there has not been a satisfactory bowel movement in 3 days. Patients with idiopathic megacolon or megarectum may require surgery if they have refractory symptoms. Depending on age, pelvic floor, and anal sphincter function, patients who have isolated megacolon can be treated with either subtotal colectomy with ileorectostomy or diverting loop ileostomy. Patients with isolated megarectum can be treated with either proctectomy and coloanal anastomosis or vertical reduction rectoplasty. Patients who have combined megacolon and megarectum can be offered diverting loop ileostomy or, if pelvic floor function is normal and they wish to avoid stoma, total proctocolectomy with ileal pouch-anal anastomosis.

Prospective randomized double-blind study of temporary sacral nerve stimulation in patients with rectal evacuatory dysfunction and rectal hyposensitivity

OBJECTIVE

Prospective randomized double-blind placebo-controlled crossover trial of 14 female patients (median age 52 [30-69] years) with proctographically defined evacuatory dysfunction (ED) and demonstrable rectal hyposensitivity (elevated thresholds to balloon distension in comparison with age- and sex-matched controls).

BACKGROUND

Sacral nerve stimulation (SNS) is an evolving treatment for constipation. However, variable outcomes might be improved by better patient selection. Evidence that the effect of SNS may be mediated by modulation of afferent signaling promotes a role in patients with ED associated with rectal hyposensation.

METHODS

SNS was performed by the standard 2-stage technique (temporary then permanent implantation). During a 4-week period of temporary stimulation, patients were randomized ON-OFF/OFF-ON for two 2-week periods. Before insertion (PRE), and during each crossover period, primary (rectal sensory thresholds) and secondary (bowel diaries, constipation, and GIQoL [gastrointestinal quality of life] scores) outcome variables were blindly assessed.

RESULTS

Thirteen patients completed the trial. Following stimulation, defecatory desire volumes to rectal balloon distension were normalized in 10 of 13 patients (PRE: mean 277 mL [234-320] vs ON: 163 mL [133-193] vs OFF: 220 mL [183-257 mL]; P = 0.006) and maximum tolerable volume in 9 of 13 (PRE: mean 350 mL [323-377] vs ON: 262 mL [219-305] vs OFF: 298 mL [256-340 mL]; P = 0.012). There was a significant increase in the percentage of successful bowel movements (PRE: median 43% [0-100] vs ON: 89% [11-100] vs OFF: 83% [11-100]; P = 0.007) and Wexner constipation scores improved (PRE: median 19 [9-26] vs ON: 10 [6-27] vs OFF: 13 [5-29]; P = 0.01). There were no significant changes in disease-specific or generic quality of life measures. Eleven patients progressed to permanent stimulation (9/11 success at 19 months).

CONCLUSIONS

Most patients with chronic constipation secondary to ED with rectal hyposensitivity responded to temporary SNS. The physiological results presented support a mechanistic role for rectal afferent modulation.

Rectal sensorimotor dysfunction in constipation

The pathophysiological mechanisms underlying chronic constipation in both adults and children remain to be unravelled. This is a not inconsiderable challenge, but is fundamental to improving management of such patients. Rectal sensorimotor function, which encompasses both sensation and motility, as well as biomechanical components (compliance, capacity), is now strongly implicated in the pathogenesis of constipation. Rectal hyposensitivity, rectal hypercompliance, increased rectal capacity, rectal motor dysfunction (phasic contractility and tone), and altered rectoanal reflex activity are all found in constipated patients, particularly in association with 'functional' disorders of defaecation (i.e. pelvic floor dyssynergia). This review covers contemporary understanding of how components of rectal sensorimotor function may contribute to symptom development in both adult and paediatric populations. The complex interaction between sensory/motor/biomechanical domains, and how best to measure these functions are addressed, and where data exist, the impact of sensorimotor dysfunction on therapeutic outcomes is highlighted.

Advances in pediatric colorectal surgical techniques

The operative management of pediatric colorectal diseases has improved significantly in recent years through the development of innovative approaches for operative exposure and a better understanding of colorectal anatomy. Advances in transanal and minimal access techniques have formed the cornerstone of this innovation, leading to improved functional outcomes, earlier recovery, and superior cosmetic results for a number of colorectal diseases. In this regard, we have witnessed a significant evolution in the way that many of these conditions are managed, particularly in the areas of anorectal malformations and Hirschsprung disease. Furthermore, a more thorough understanding of the pathophysiology underlying encopresis and true fecal continence has led to novel and less invasive approaches to the operative management of these conditions. The goal of this review is to describe the evolution of operative management pertaining to these diseases, with an emphasis on technical aspects and relevant clinical pitfalls.

The dilated bowel: a liability and an asset

The gastrointestinal tract responds to significant mechanical or functional obstruction by dilatation and hypertrophy of the segment proximal to the obstruction. Excessive dilatation compromises motility, and absorption and is associated with considerable morbidity (intraluminal stasis, sepsis) such that bowel dilatation represents a major liability that predisposes the patient to intestinal failure. The dilated bowel proximal to an obstruction provides valuable autologous material for reconstruction with "tissue appropriate to the part." Bowel elongation and dilatation are integral to the natural intestinal adaptation response to loss of small bowel and can also be induced through a structured "Bowel Expansion" program. The additional absorptive tissue that is progressively generated is essential for reconstruction of the bowel (tailoring and lengthening), to restore gastrointestinal dynamics (effective propulsion and absorption), and to reduce morbidity (intraluminal stasis, sepsis). In enhancing the prospects for enteral autonomy, dilatation and elongation of the residual autologous bowel are crucial to long-term survival and good quality life, and represent a most welcome asset. This paper reviews the impact and management of bowel dilatation along the gastrointestinal tract.

Anal incontinence

Anal incontinence is a life restricting condition that is sometimes challenging to treat. There is an equal gender prevalence, however women are more likely to present particularly early in life, as a result of obstetric injury. This is still one of the leading causes of anal incontinence and sphincter tears can be missed at the time of delivery. As a result, there is a heightened awareness for sphincter injury based on risk assessment, digital rectal examination and an endo-anal ultrasound. Surgical repair is still invaluable in the presence of disruption and salvage procedures for severe refractory incontinence such as the dynamic gracilloplasty and the artificial bowel sphincter continue to be perfected. Mini invasive procedures such as rectal irrigation and sacral neuromodulaton have had a successful outcome and we have had to depend less on the more invasive treatments. Above all there is a growing need to protect not only the baby but also the pelvic floor and anal sphincter from traumatic deliveries, through early risk assessment and research.

Clinical presentation and patterns of slow transit constipation do not predict coexistent upper gut dysmotility

BACKGROUND

Slow transit constipation (STC) is associated with upper gastrointestinal tract motor abnormalities in a subset of patients. This could influence the clinical approach, particularly in those rare cases where surgical management is considered.

AIMS

To identify factors that predict proximal gut dysmotility in patients with STC.

METHODS

Esophageal and small bowel motor function were evaluated in 77 patients with STC. Severity and pattern of colonic transit delay, prevalence of a co-existent rectal evacuatory disorder, and type (if present), and duration, and onset of constipation symptoms were compared.

RESULTS

Of the 77 patients studied, 43% exhibited altered motor function in the esophagus and/or small bowel. Frequency of defecation was lower in these patients than in those without upper gastrointestinal dysmotility (0.5 +/- 0.1 vs. 1.3 +/- 0.3 bowel movements/per week, respectively; P = 0.04). Severity and patterns of colonic transit delay and the mechanism associated with the onset of constipation symptoms or with their duration were similar in subjects with or without upper gastrointestinal tract dysmotility. Small bowel but not esophageal motor dysfunction was more frequently associated with a co-existent rectal evacuatory disorder (P = 0.01).

CONCLUSION

Upper gastrointestinal tract dysmotility in patients with STC is frequent, but prediction on the basis of clinical history and characteristics of colonic transit is problematic.

Surgical treatment of patients with constipation and fecal incontinence

Patients with constipation and fecal incontinence usually come to the attention of the surgeon when conservative measures have failed to alleviate sufficiently severe symptoms. Following detailed clinical and physiologic assessment, the surgeon should tailor the procedure to specific underlying physiologic abnormalities to restore function. This article describes the rationale, indications (including patient selection), results, and current position controversies of surgical procedures for constipation and fecal incontinence, dividing these into those regarded as historical, contemporary, or evolving. Reported surgical outcome data must be interpreted with caution because for most studies the evidence is of low quality, making comparison of different procedures problematic and emphasizing the need for better designed and conducted clinical trials.

Novel concepts in the diagnosis, pathophysiology and management of idiopathic megabowel

A proportion of patients with intractable constipation have persistent dilatation of the bowel, which in the absence of an organic cause is termed idiopathic megabowel (IMB). Whilst uncommon, this condition results in considerable morbidity. Traditional methods of identifying such patients are associated with inherent methodological limitations with anorectal manometry and contrast studies overestimating and underestimating the prevalence of the condition, respectively. Recently, controlled, pressure-based distension during fluoroscopic imaging has allowed more accurate identification of patients on the basis of a rectal diameter > 6.3 cm at the minimum distension pressure. Histopathological abnormalities of all three final effectors of sensorimotor function have been reported, although it remains unclear whether these changes are primary, secondary or epiphenomic. Physiological abnormalities of sensorimotor function, namely impaired perception of rectal distension and delayed colonic transit are well documented in patients with IMB. Further, the recent demonstration of two subgroups of patients, defined on the basis of rectal compliance, suggests the possibility that they differ pathophysiologically, although the clinical relevance of this distinction is uncertain. Surgery is performed when conservative therapy is ineffective or poorly tolerated. Numerous procedures have been attempted with variable success rates and significant mortality and morbidity. Surgery should preferably be performed in specialist centres given the relative infrequency with which such patients are encountered, and that they require comprehensive clinical, psychological and physiological evaluation preoperatively.

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.