Rectal hyposensitivity: pathophysiological mechanisms

Constipated patients with functional defecatory disorder have secondary rectal hyposensitivity due to altered rectal biomechanics

BACKGROUND AND AIM

Rectal hyposensitivity (RH) is common in constipation and often coexists with functional defecatory disorder (FDD). Rectal sensory thresholds are routinely evaluated with the anorectal manometry probe; however, the gold standard for the assessment of rectal sensitivity is with a barostat, use of which is limited by time constraints and availability. A novel rapid barostat bag (RBB) may facilitate measurements of rectal sensitivity. The aim is to evaluate the relationship between RH (measured by the RBB) and FDD (defined as any minor disorder of rectoanal coordination by the London classification) in constipated patients.

METHODS

Consecutive constipated patients referred for anorectal function testing underwent anorectal manometry with the 3D-HDAM probe as well as rectal sensation testing with the RBB pump. RH was defined by volume to first sensation >30%, urge to defecate >80%, or discomfort >100% (normalized to rectal capacity).

RESULTS

Fifty-three percent of constipated patients had RH. Patients with FDD had a significantly increased volume to first sensation (134.5 mL vs 102.0, P = 0.02), urge to defecate (187.0 mL vs 149.0, P = 0.04), and rectal capacity (253.5 mL vs 209.0, P = 0.04) compared to constipated patients without FDD. There was no difference in normalized sensory thresholds (percent of rectal capacity) nor the prevalence of hyposensitivity to each sensory threshold nor overall hyposensitivity.

CONCLUSION

Patients with FDD, when measured with the RBB, have increased sensory thresholds on volumetric distension, but RH was not observed when sensory threshold volume were normalized to rectal capacity. This may reflect "secondary" RH due to altered rectal biomechanics.

Sacral Neuromodulation for defecation disorders after non oncologic pelvic surgery

PURPOSE

Defecation disorders (DD) can sometimes affect the outcomes of pelvic or colorectal surgery. The aim of the present study is to evaluate the role of sacral neuromodulation for the treatment of constipation and other evacuation disorders after surgery.

METHODS

A retrospective analysis in all the consecutive patients that underwent sacral nerve modulation (SNM) for DD arisen or worsened after pelvic or colorectal surgery was performed from January 2010 to December 2020. DD were defined starting from Rome IV Criteria, and according to manometric results, all patients were further divided into the two subgroups: inadequate defecatory propulsion and dyssynergic defecation. Cleveland Clinic Constipations Score (CCCS) and SF-36 have been evaluated in the time.

RESULTS

Thirty-seven patients have been included in the study. Twenty-seven out of thirty-seven (73.3%) patients had experienced sufficient benefits to implant the definitive device, and 22 patients (59.4% of tested and 81.5% of permanently implanted) still had the device functioning after a mean follow-up of 6.3 years. The most represented manometric pattern was inadequate propulsive function (59% of patients). CCCS at preoperative assessment for all patients was 17.5 with a reduction to 10.4 at the first year of follow-up (p < 0.001).

CONCLUSION

SNM appears to be a feasible, safe, and well-tolerated procedure with durable benefit in the long-term treatment of defecatory dysfunction after pelvic or colorectal surgery for benign diseases.

Rectal sensitivity and associated factors in patients with different subtypes of functional defecation disorder

OBJECTIVE

To investigate rectal sensitivity and associated factors in patients with different subtypes of functional defecation disorder (FDD).

METHODS

We segregated individuals diagnosed with FDD into two groups based on their defecation patterns: those with dyssynergic defecation and those with inadequate defecatory propulsion. We gathered general information through questionnaires and assessed rectal sensitivity using anorectal manometry. The rectal sensitivity performances of the two groups were compared; the factors related to rectal sensitivity were analyzed to determine the factors associated with rectal sensitivity, and the effect of biofeedback therapy on rectal sensitivity was clarified.

RESULTS

Rectal sensitivity in different subtypes of FDD decreased, and the difference between the two groups was not statistically significant ( P  > 0.05). There were no statistically significant differences in the first constant sensation volume, defecatory desire volume, and maximum tolerable volume between the different subtypes of FDD ( P  > 0.05). Multi-factor binary logistic regression analysis showed that age, constipation symptom score, and diabetes were all independent risk factors for decreased rectal sensitivity ( P  < 0.05). There were no statistically significant differences between the prior- and post-biofeedback therapy in the first constant sensation volume, defecatory desire volume, and maximum tolerable volume ( P  > 0.05).

CONCLUSION

Rectal sensitivity in different subtypes of FDD decreased. Age, constipation symptom score, and diabetes were independent risk factors for decreased rectal sensitivity. Short-term biofeedback therapy did not improve rectal hyposensitivity in patients with FDD.

Clinical significance and related factors of rectal hyposensitivity in patients with functional defecation disorder

Background

Rectal hyposensitivity (RH) is not uncommon in patients with functional defecation disorder (FDD). FDD patients with RH are usually unsatisfied with their treatment.

Aims

The aim of this study was to find the significance of RH in patients with FDD and the related factors of RH.

Methods

Patients with FDD first completed clinical questionnaires regarding constipation symptoms, mental state, and quality of life. Then anorectal physiologic tests (anorectal manometry and balloon expulsion test) were performed. Rectal sensory testing (assessing rectal response to balloon distension using anorectal manometry) was applied to obtain three sensory thresholds. Patients were separated into three groups (non-RH, borderline RH, and RH) based on the London Classification. The associations between RH and clinical symptoms, mental state, quality of life, and rectal/anal motility were investigated.

Results

Of 331 included patients with FDD, 87 patients (26.3%) had at least one abnormally elevated rectal sensory threshold and 50 patients (15.1%) were diagnosed with RH. Patients with RH were older and mostly men. Defecation symptoms were more severe (p = 0.013), and hard stool (p < 0.001) and manual maneuver (p = 0.003) were more frequently seen in the RH group. No difference in rectal/anal pressure was found among the three groups. Elevated defecatory desire volume (DDV) existed in all patients with RH. With the number of elevated sensory thresholds increasing, defecation symptoms got more severe (r = 0.35, p = 0.001). Gender (male) (6.78 [3.07-15.00], p < 0.001) and hard stool (5.92 [2.28-15.33], p < 0.001) were main related factors of RH.

Conclusion

Rectal hyposensitivity plays an important role in the occurrence of FDD and is associated with defecation symptom severity. Older male FDD patients with hard stool are prone to suffer from RH and need more care.

Review of the indications, methods, and clinical utility of anorectal manometry and the rectal balloon expulsion test

BACKGROUND

Anorectal manometry (ARM) comprehensively assesses anorectal sensorimotor functions.

PURPOSE

This review examines the indications, techniques, interpretation, strengths, and weaknesses of high-resolution ARM (HR-ARM), 3-dimensional high-resolution anorectal manometry (3D-HR-ARM), and portable ARM, and other assessments (i.e., rectal sensation and rectal balloon expulsion test) that are performed alongside manometry. It is based on a literature search of articles related to ARM in adults. HR-ARM and 3D-HR-ARM are useful for diagnosing defecatory disorders (DD), to identify anorectal sensorimotor dysfunction and guide management in patients with fecal incontinence (FI), constipation, megacolon, and megarectum; and to screen for anorectal structural (e.g., rectal intussusception) abnormalities. The rectal balloon expulsion test is a useful, low-cost, radiation-free, outpatient assessment tool for impaired evacuation that is performed and interpreted in conjunction with ARM. The anorectal function tests should be interpreted with reference to age- and sex-matched normal values, clinical features, and results of other tests. A larger database of technique-specific normal values and newer paradigms of analyzing anorectal pressure profiles will increase the precision and diagnostic utility of HR-ARM for identifying abnormal mechanisms of defecation and continence.

Faecal incontinence in adults

Faecal incontinence, which is defined by the unintentional loss of solid or liquid stool, has a worldwide prevalence of ≤7% in community-dwelling adults and can markedly impair quality of life. Nonetheless, many patients might not volunteer the symptom owing to embarrassment. Bowel disturbances, particularly diarrhoea, anal sphincter trauma (obstetrical injury or previous surgery), rectal urgency and burden of chronic illness are the main risk factors for faecal incontinence; others include neurological disorders, inflammatory bowel disease and pelvic floor anatomical disturbances. Faecal incontinence is classified by its type (urge, passive or combined), aetiology (anorectal disturbance, bowel symptoms or both) and severity, which is derived from the frequency, volume, consistency and nature (urge or passive) of stool leakage. Guided by the clinical features, diagnostic tests and therapies are implemented stepwise. When simple measures (for example, bowel modifiers such as fibre supplements, laxatives and anti-diarrhoeal agents) fail, anorectal manometry and other tests (endoanal imaging, defecography, rectal compliance and sensation, and anal neurophysiological tests) are performed as necessary. Non-surgical options (diet and lifestyle modification, behavioural measures, including biofeedback therapy, pharmacotherapy for constipation or diarrhoea, and anal or vaginal barrier devices) are often effective, especially in patients with mild faecal incontinence. Thereafter, perianal bulking agents, sacral neuromodulation and other surgeries may be considered when necessary.

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.

Barostat or syringe-assisted sensory biofeedback training for constipation with rectal hyposensitivity: A randomized controlled trial

BACKGROUND

Rectal hyposensitivity (RH) is a well-known pathophysiological dysfunction in chronic constipation. Whether biofeedback training improves RH and restores bowel function is unknown.

AIM

To investigate the efficacy of barostat-assisted sensory training (BAST) with syringe-assisted sensory training (SAST) in patients with RH in a randomized controlled trial.

METHODS

Patients with RH and chronic constipation (Rome III) were randomized to receive 6 biweekly sessions of BAST or SAST. Verbal/visual feedback was provided during repeated rectal distensions to improve defecation desire/urge and first sensations with either 10-cm balloon connected to barostat (BAST) or 4-cm balloon connected to syringe and manometry probe (SAST). Sensory thresholds, bowel symptoms, and therapist and patient's rating of treatments were compared. The primary outcome (responders) was the improvement in ≥2 sensory thresholds.

RESULTS

Sixty-six patients were enrolled: 32 received BAST, 34 received SAST, and 56 completed study. There were significantly more responders in BAST group than SAST (78% vs. 53%, p = 0.0320). Rectal sensation normalized in 81% with BAST compared to 56% with SAST (p = 0.0270). When compared to baseline, desire and urge to defecate thresholds and bowel satisfaction improved with BAST (p = 0.0013; p = 0.0002; p = 0.0001) and SAST (p = 0.0012; p = 0.0001; p < 0.0001) and number of complete spontaneous bowel movements with BAST (p = 0.0029) but without inter-group differences. Therapists rated BAST as superior to SAST (p < 0.0001), but patients rated both equally.

CONCLUSIONS

Sensory biofeedback training was effective and significantly improved rectal sensation and constipation symptoms. Although both techniques were useful, the novel BAST was more efficacious and easier to administer for treating RH.

Diagnostic Strategy and Tools for Identifying Defecatory Disorders

This article reviews the indications, techniques, interpretation, strengths, and weaknesses of tests (anal manometry, anal surface electromyography, rectal balloon expulsion test, barium and MRI defecography, assessment of rectal compliance and sensation, and colonic transit) that are used diagnose defecatory disorders in constipated patients. The selection of tests and the sequence in which they are performed should be individualized to and interpreted in the context of the clinical features. Because anorectal functions are affected by age, results should be interpreted with reference to age- and sex-matched normal values for the same technique.

Development of colonic transit time and ultrasound imaging tools as objective indicators for assessing abnormal defecation associated with food intake: a narrative review based on previous scientific knowledge

Background

Functional gastrointestinal disorders (FGIDs) involve chronic or persistent gastrointestinal symptoms. Laboratory tests show no organic lesions, and the symptoms are due to dysfunction. The most typical FGID is irritable bowel syndrome (IBS). In IBS patients, defecation disorders are common and have adverse effects on daily life. The proper evaluation and analysis of colonic transit are important for the management of defecation disorders in IBS patients. In addition, dietary intake and lifestyle affect colonic transit. An accurate assessment of such factors can guide management, leading to improvements in colonic transit and the resolution of defecation disorders.

Main topic

The Rome IV diagnostic criteria for IBS are based on subjective symptoms, which must be communicated and explained by the patient, limiting their application. Colonic transit time and ultrasonography are objective tools that can be used to diagnose IBS. In particular, previous studies used colonic transit to accurately distinguish between constipation and normal stool passage and to assess delayed gastrointestinal motility. Diet and lifestyle modifications can improve colonic transit and ameliorate bowel dysfunction.

Conclusion

Colonic transit can be improved by modifying lifestyle factors. Defecation disorders in IBS patients may be resolved by focusing on such factors. In the future, methods of visualizing defecation disorders due to impaired gastrointestinal motility and objective indicators of the associated abdominal symptoms need to be investigated.

Chronic constipation in adults: Contemporary perspectives and clinical challenges. 1: Epidemiology, diagnosis, clinical associations, pathophysiology and investigation

BACKGROUND

Chronic constipation is a prevalent disorder that affects patients' quality of life and consumes resources in healthcare systems worldwide. In clinical practice, it is still considered a challenge as clinicians frequently are unsure as to which treatments to use and when. Over a decade ago, a Neurogastroenterology & Motility journal supplement devoted to the investigation and management of constipation was published (2009; 21 (Suppl.2)). This included seven articles, disseminating all themes covered during a preceding 2-day meeting held in London, entitled "Current perspectives in chronic constipation: a scientific and clinical symposium." In October 2018, the 3rd London Masterclass, entitled "Contemporary management of constipation" was held, again over 2 days. All faculty members were invited to author two new review articles, which represent a collective synthesis of talks presented and discussions held during this meeting.

PURPOSE

This article represents the first of these reviews, addressing epidemiology, diagnosis, clinical associations, pathophysiology, and investigation. Clearly, not all aspects of the condition can be covered in adequate detail; hence, there is a focus on particular "hot topics" and themes that are of contemporary interest. The second review addresses management of chronic constipation, covering behavioral, conservative, medical, and surgical therapies.

Comparison of clinical and paraclinical characteristics of patients with urge, mixed, and passive fecal incontinence: a systematic literature review

PURPOSE

Two subgroups of fecal incontinence (FI) are described in literature and used in clinical practice. However, the pertinence of this classification of FI is still unknown as there are no clear established guidelines. To a better understanding, we performed a systematic review to characterize the different types of FI (active, passive, or mixed) on the basis of clinical presentation and complementary explorations.

METHODS

This systematic literature review was performed in reference to recommendations for systematic review using PRISMA guidelines without date restriction, until May 2020. This systematic review was performed without temporal limitation using MEDLINE-PubMed, Cochrane Library, and Google Scholar databases.

RESULTS

Six hundred nine unique citations were identified from all the databases combined. Of those, 21 studies met the inclusion criteria, with 8 retrospective observational studies and 13 prospective observational studies. There was a lack of homogeneity in definitions of passive and urge (active) FI among studies. Prevalence of passive and urge FI was respectively of 4.0-5.0 and 15.0-35.0%. Clinical characteristics, physical examination, and endoanal imaging were not evaluated in most studies. In anorectal manometry, maximal squeeze pressure was higher in passive FI subgroup in most studies and results regarding maximal resting pressure remain discordant. There seemed to be no difference regarding first sensation volume and maximal tolerable volume among subgroups. A few studies evaluated pudendal terminal nerve motor latency with no difference among subgroups.

CONCLUSION

There is a lack of well-conducted prospective studies comparing the different subtypes of FI with validated definitions in both clinical and paraclinical examinations.

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.).

Association between opioid usage and rectal dysfunction in constipation: A cross-sectional study of 2754 patients

BACKGROUND

Opioid use has reached epidemic proportions. In contrast to the known effect of opioids on gut transit, the effect on rectal sensorimotor function has not been comprehensively investigated.

METHODS

Cross-sectional (hypothesis-generating) study of anorectal physiology studies in 2754 adult patients referred to a tertiary unit (2004-2016) for investigation of functional constipation (defined by "derived" Rome IV core criteria). Statistical associations between opioid usage, symptoms, and anorectal physiological variables were investigated. Opioids were sub-classified as prescriptions for mild-moderate or moderate-severe pain.

KEY RESULTS

A total of 2354 patients (85.5%) were classified as non-opioid users, 162 (5.9%) as opioid users for mild-moderate pain, and 238 (8.6%) for moderate-severe pain. Opioids for moderate-severe pain were associated with increased symptomatic severity (Cleveland Clinic constipation score 18.5 vs 15.1; mean difference 2.9 [95%-CI 2.3-3.6]; P < .001), rectal hyposensitivity (odds ratio 1.74 [95%-CI 1.23-2.46]; P = .002), functional evacuation disorders (odds ratio 1.73 [95%-CI 1.28-2.34]; P < .001), and delayed whole-gut transit (odds ratio 1.68 [95%-CI 1.19-2.37]; P = .003). Differences in anorectal variables between opioid users for mild-moderate pain and non-opioid users were not statistically significant. Hierarchical opioid use (non vs mild-moderate vs moderate-severe) was associated with decreasing proportions of patients with no physiological abnormality on testing (40.2% vs 38.1% vs 29.2%) and increasing proportions with both delayed whole-gut transit and rectal sensorimotor dysfunction (16.6% vs 17.5% vs 28.5%).

CONCLUSIONS AND INFERENCES

Opioid use is over-represented in patients referred for investigation of constipation. Opioids for moderate-severe pain are associated with rectal sensorimotor abnormalities. Further studies are required to determine whether this association indicates causation.

Defective Conduction of Anorectal Afferents Is a Very Prevalent Pathophysiological Factor Associated to Fecal Incontinence in Women

Background/Aims

Fecal incontinence (FI) is a prevalent condition among women. While biomechanical motor components have been thoroughly researched, anorectal sensory aspects are less known. We studied the pathophysiology of FI in community-dwelling women, specifically, the conduction through efferent/afferent neural pathways.

Methods

A cross-sectional study was conducted on 175 women with FI and 19 healthy volunteers. The functional/structural study included anorectal manometry/endoanal ultrasound. Neurophysiological studies including pudendal nerve terminal motor latency (PNTML) and sensory-evoked-potentials to anal/rectal stimulation (ASEP/RSEP) were conducted on all healthy volunteers and on 2 subgroups of 42 and 38 patients, respectively.

Results

The main conditions associated with FI were childbirth (79.00%) and coloproctological surgery (37.10%). Cleveland score was 11.39 ± 4.09. Anorectal manometry showed external anal sphincter and internal anal sphincter insufficiency in 82.85% and 44.00%, respectively. Sensitivity to rectal distension was impaired in 27.42%. Endoanal ultrasound showed tears in external anal sphincter (60.57%) and internal anal sphincter disruptions (34.80%). Abnormal anorectal sensory conduction was evidenced through ASEP and RSEP in 63.16% and 50.00% of patients, respectively, alongside reduced activation of brain cortex to anorectal stimulation. In contrast, PNTML was delayed in only 33.30%. Stools were loose/very loose in 56.70% of patients.

Conclusions

Pathophysiology of FI in women is mainly associated with mechanical sphincter dysfunctions related to either muscle damage or, to a lesser extent, impaired efferent conduction at pudendal nerves. Impaired conduction through afferent anorectal pathways is also very prevalent in women with FI and may play an important role as a pathophysiological factor and as a potential therapeutic target.

Normal Rectal Filling Sensations in Patients with an Enlarged Rectum

BACKGROUND

Increased rectal volume is believed to be associated with diminished rectal sensation, i.e., rectal hyposensitivity.

AIMS

To demonstrate that patients with increased rectal volumes do not automatically have diminished rectal filling sensations.

METHODS

We, retrospectively, observed 100 adult patients with defecation problems, and 44 healthy controls who had undergone anorectal function tests. Using the balloon retention test, we analyzed the distribution of rectal volumes and pressures at different rectal filling sensation levels.

RESULTS

We found variance in the distribution of rectal volumes at all levels, while rectal pressures showed a normal distribution. We found no correlation between rectal volumes and pressures (constant sensation, r = 0.140, P = 0.163, urge sensation, r = - 0.090, P = 0.375, and maximum tolerable volumes, r = - 0.091, P = 0.366), or when taking age and sex into account. The findings for the patient group were congruent with those for the control group.

CONCLUSIONS

Participants with increased rectal volumes do not experience increased rectal pressures at any sensation level. This finding, combined with the knowledge that rectal pressure triggers rectal filling sensation, indicates that rectal filling sensations in patients with increased rectal volumes are not diminished. Therefore, "rectal hyposensitivity" should be reserved for patients with increased rectal pressure thresholds, and not for "abnormally" increased rectal volume thresholds.

Expert consensus document: Advances in the evaluation of anorectal function

Faecal incontinence and evacuation disorders are common, impair quality of life and incur substantial economic costs worldwide. As symptoms alone are poor predictors of underlying pathophysiology and aetiology, diagnostic tests of anorectal function could facilitate patient management in those cases that are refractory to conservative therapies. In the past decade, several major technological advances have improved our understanding of anorectal structure, coordination and sensorimotor function. This Consensus Statement provides the reader with an appraisal of the current indications, study performance characteristics, clinical utility, strengths and limitations of the most widely available tests of anorectal structure (ultrasonography and MRI) and function (anorectal manometry, neurophysiological investigations, rectal distension techniques and tests of evacuation, including defecography). Additionally, this article provides our consensus on the clinical relevance of these tests.

The Mexican consensus on chronic constipation

INTRODUCTION

Significant advances have been made in the knowledge and understanding of the epidemiology, pathophysiology, diagnosis, and treatment of chronic constipation, since the publication of the 2011 guidelines on chronic constipation diagnosis and treatment in Mexico from the Asociación Mexicana de Gastroenterología.

AIMS

To present a consensus review of the current state of knowledge about chronic constipation, providing updated information and integrating the new scientific evidence.

METHODS

Three general coordinators reviewed the literature published within the time frame of January 2011 and January 2017. From that information, 62 initial statements were formulated and then sent to 12 national experts for their revision. The statements were voted upon, using the Delphi system in 3 voting rounds (2 electronic and one face-to-face). The statements were classified through the GRADE system and those that reached agreement >75% were included in the consensus.

RESULTS AND CONCLUSIONS

The present consensus is made up of 42 final statements that provide updated knowledge, supplementing the information that had not been included in the previous guidelines. The strength of recommendation and quality (level) of evidence were established for each statement. The current definitions of chronic constipation, functional constipation, and opioid-induced constipation are given, and diagnostic strategies based on the available diagnostic methods are described. The consensus treatment recommendations were established from evidence on the roles of diet and exercise, fiber, laxatives, new drugs (such as prucalopride, lubiprostone, linaclotide, plecanatide), biofeedback therapy, and surgery.

Electrophysiological characterization of human rectal afferents

It is presumed that extrinsic afferent nerves link the rectum to the central nervous system. However, the anatomical/functional existence of such nerves has never previously been demonstrated in humans. Therefore, we aimed to identify and make electrophysiological recordings in vitro from extrinsic afferents, comparing human rectum to colon. Sections of normal rectum and colon were procured from anterior resection and right hemicolectomy specimens, respectively. Sections were pinned and extrinsic nerves dissected. Extracellular visceral afferent nerve activity was recorded. Neuronal responses to chemical [capsaicin and "inflammatory soup" (IS)] and mechanical (Von Frey probing) stimuli were recorded and quantified as peak firing rate (range) in 1-s intervals. Twenty-eight separate nerve trunks from eight rectums were studied. Of these, spontaneous multiunit afferent activity was recorded in 24 nerves. Peak firing rates increased significantly following capsaicin [median 6 (range 3-25) spikes/s vs. 2 (1-4), P < 0.001] and IS [median 5 (range 2-18) spikes/s vs. 2 (1-4), P < 0.001]. Mechanosensitive "hot spots" were identified in 16 nerves [median threshold 2.0 g (range 1.4-6.0 g)]. In eight of these, the threshold decreased after IS [1.0 g (0.4-1.4 g)]. By comparison, spontaneous activity was recorded in only 3/30 nerves studied from 10 colons, and only one hot spot (threshold 60 g) was identified. This study confirms the anatomical/functional existence of extrinsic rectal afferent nerves and characterizes their chemo- and mechanosensitivity for the first time in humans. They have different electrophysiological properties to colonic afferents and warrant further investigation in disease states.

Chronic Constipation: a Review of Current Literature

Chronic constipation is a common health condition representing a substantial proportion of primary care visits and referrals to specialist providers. Chronic constipation can have a significant negative effect on health-related quality of life and has been associated with psychological distress in severely affected patients. It has the potential to cause patients to curtail work, school, and social activities. While different pathophysiological mechanisms have been implicated in the development of chronic constipation, in some instances, the causes of chronic constipation are not easily determined. Expenditures for the evaluation and management of chronic constipation represent a significant burden on patients and payers, and it is important for clinicians to have a clear understanding of the different pathophysiological mechanisms associated with constipation, understand the different testing modalities and treatments that are available including their appropriateness and limitations, and tailor that knowledge to the management of individual patients.

Cortical evoked potentials in response to rapid balloon distension of the rectum and anal canal

BACKGROUND

Neurophysiological evaluation of anorectal sensory function is hampered by a paucity of methods. Rapid balloon distension (RBD) has been introduced to describe the cerebral response to rectal distension, but it has not successfully been applied to the anal canal.

METHODS

Nineteen healthy women received 30 RBDs in the rectum and the anal canal at intensities corresponding to sensory and unpleasantness thresholds, and response was recorded as cortical evoked potentials (CEPs) in 64-channels. The anal canal stimulations at unpleasantness level were repeated after 4 min to test the within-day reproducibility. CEPs were averaged, and to overcome latency variation related to jitter the spectral content of single sweeps was also computed.

KEY RESULTS

Repeated stimulation of the anal canal generated CEPs with similar latencies but smaller amplitudes compared to those from the rectum. Due to latency jitter, reproducibility of averaged CEPs was lower than what was found in the rectum. The most reproducible feature was N2P2 peak-to-peak amplitude with intra-class correlation coefficient (ICC) of 0.7 and coefficient of variation (CV) of 18%. Spectral content of the single sweeps showed reproducibility with ICCs for all bands >0.8 and corresponding CVs <7%.

CONCLUSIONS & INFERENCES

Cortical potentials evoked from the anal canal are challenged by latency jitter likely related to variability in muscle tone due to the distensions. Using single-sweep analysis, anal CEPs proved to be reproducible and should be used in future evaluation of the anal function.

Assessment of rectal afferent neuronal function and brain activity in patients with constipation and rectal hyposensitivity

BACKGROUND

Blunted rectal sensation (rectal hyposensitivity: RH) is present in almost one-quarter of patients with chronic constipation. The mechanisms of its development are not fully understood, but in a proportion, afferent dysfunction is likely. To determine if, in patients with RH, alteration of rectal sensory pathways exists, rectal evoked potentials (EPs) and inverse modeling of cortical dipoles were examined.

METHODS

Rectal EPs (64 channels) were recorded in 13 patients with constipation and RH (elevated thresholds to balloon distension) and 11 healthy controls, in response to electrical stimulation of the rectum at 10 cm from the anal verge using a bipolar stimulating electrode. Stimuli were delivered at pain threshold. Evoked potential peak latencies and amplitudes were analyzed, and inverse modeling was performed on traces obtained to determine the location of cortical generators.

KEY RESULTS

Pain threshold was higher in patients than controls [median 59 (range 23-80) mA vs 24 (10-55) mA; P = 0.007]. Median latency to the first negative peak was 142 (±24) ms in subjects compared with 116 (±15) ms in controls (P = 0.004). There was no difference in topographic analysis of EPs or location of cortical activity demonstrated by inverse modeling between groups.

CONCLUSIONS & INFERENCES

This study is the first showing objective evidence of alteration in the rectal afferent pathway of individuals with RH and constipation. Prolonged latencies suggest a primary defect in sensory neuronal function, while cerebral processing of visceral sensory information appears normal.

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.

Rectal hyposensitivity for non-noxious stimuli, postprandial hypersensitivity and its correlation with symptoms in complete spinal cord injury with neurogenic bowel dysfunction

STUDY DESIGN

Prospective clinical study.

OBJECTIVES

To assess fasting and postprandial (PP) perception of rectal distension and its correlation with symptoms in patients with spinal cord injury (SCI) and neurogenic bowel dysfunction compared to ten healthy subjects (HS).

SETTING

Experimental Medicine and Motility Unit, Mexico General Hospital and National Institute of Rehabilitation.

METHODS

Twenty patients with complete SCI at cervical, thoracic and lumbar levels [American Spinal Injury Association (ASIA) A] were studied. Rectal sensitivity was evaluated with a barostat.

RESULTS

In SCI patients, while lower the rectal tone more time was used for defecate (R=0.50, P=0.048) and more PP episodes of fecal incontinence occur (R=0.54, P=0.030). The thresholds for non-noxious stimuli of first (23.6 mmHg, CI 19.5-27.7) vs 14.0 (CI 10.9-17.1), P=0.004; gas (27.9 mmHg, CI 19.9-35.8) vs 17.9 mmHg (CI 14.25-21.69), P=0.02 and urge-to-defecate sensation (33.2 mmHg, CI 27.5-38.8) vs 22.4 mmHg (CI 17.9-26.9), P=0.01 were reported by SCI patients at higher pressure than HS, respectively. SCI patients reported PP pain sensation at a lower pressure than controls (27.8 mmHg, CI 21.5-34.2 vs 36.5 mmHg, CI 31.8-41.2), P=0.04.

CONCLUSION

SCI patients preserve rectal sensation, present rectal hyposensitivity for non-noxious stimuli and PP hypersensitivity. Lower rectal tone was related to the time used for defecate and with fecal incontinence. The results suggest that an intact neural transmission between the spinal cord and higher centres is indispensable for noxious stimulus, but not for non-noxious stimuli. Also, barostat sensitivity studies can complement ASIA criteria to verify a complete injury.

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.

The physiology of human defecation

Human defecation involves integrated and coordinated sensorimotor functions, orchestrated by central, spinal, peripheral (somatic and visceral), and enteric neural activities, acting on a morphologically intact gastrointestinal tract (including the final common path, the pelvic floor, and anal sphincters). The multiple factors that ultimately result in defecation are best appreciated by describing four temporally and physiologically fairly distinct phases. This article details our current understanding of normal defecation, including recent advances, but importantly identifies those areas where knowledge or consensus is still lacking. Appreciation of normal physiology is central to directed treatment of constipation and also of fecal incontinence, which are prevalent in the general population and cause significant morbidity.

Consensus statement AIGO/SICCR: Diagnosis and treatment of chronic constipation and obstructed defecation (part I: Diagnosis)

Chronic constipation is a common and extremely trou-blesome disorder that significantly reduces the quality of life, and this fact is consistent with the high rate at which health care is sought for this condition. The aim of this project was to develop a consensus for the diagnosis and treatment of chronic constipation and obstructed defecation. The commission presents its results in a “Question-Answer” format, including a set of graded recommendations based on a systematic review of the literature and evidence-based medicine. This section represents the consensus for the diagnosis. The history includes information relating to the onset and duration of symptoms and may reveal secondary causes of constipation. The presence of alarm symptoms and risk factors requires investigation. The physical examination should assess the presence of lesions in the anal and perianal region. The evidence does not support the routine use of blood testing and colonoscopy or barium enema for constipation. Various scoring systems are available to quantify the severity of constipation; the Constipation Severity Instrument for constipation and the obstructed defecation syndrome score for obstructed defecation are the most reliable. The Constipation-Related Quality of Life is an excellent tool for evaluating the patient‘s quality of life. No single test provides a pathophysiological basis for constipation. Colonic transit and anorectal manometry define the pathophysiologic subtypes. Balloon expulsion is a simple screening test for defecatory disorders, but it does not define the mechanisms. Defecography detects structural abnormalities and assesses functional parameters. Magnetic resonance imaging and/or pelvic floor sonography can further complement defecography by providing information on the movement of the pelvic floor and the organs that it supports. All these investigations are indicated to differentiate between slow transit constipation and obstructed defecation because the treatments differ between these conditions.

Fecal incontinence in men: coexistent constipation and impact of rectal hyposensitivity

BACKGROUND

The pathophysiology of fecal incontinence in men is poorly established.

OBJECTIVE

The aim of this study was to assess the coexistence of constipation and determine the impact of rectal sensorimotor dysfunction in males with fecal incontinence.

SETTING

This study was conducted at a tertiary referral center.

PATIENTS

Included were adult male patients referred for the investigation of fecal incontinence over a 5-year period who underwent full anorectal physiology testing and completed a standardized symptom questionnaire.

INTERVENTION

Standardized symptom questionnaires were fully completed, and anorectal physiologic test results (including evacuation proctography) were evaluated.

MAIN OUTCOME MEASURES

: The primary outcomes measured were the frequency of symptoms of associated constipation, the association of blunted rectal sensation (rectal hyposensitivity) with symptoms, and other physiologic measures.

RESULTS

One hundred sixty patients met the inclusion criteria, and 47% of these patients described concurrent constipation. Fifty-four patients (34%) had sphincter dysfunction on manometry, only 19 of whom had structural abnormalities on ultrasound. Overall, 28 patients (18%) had rectal sensory dysfunction, 26 (93%) of whom had rectal hyposensitivity. Patients with rectal hyposensitivity were more likely to subjectively report constipation (77%) in comparison with patients with normal rectal sensation (44%; p = 0.001), allied with decreased bowel frequency (19% vs 2%; p = 0.003) and a sense of difficulty evacuating stool (27% vs 8%; p = 0.008). Cleveland Clinic constipation scores were higher in patients with rectal hyposensitivity (median score, 13 (interquartile range: 8-17) vs normosensate, 9 (5-13); p = 0.004). On proctography, a higher proportion of patients with rectal hyposensitivity had protracted defecation (>180 s; 35% vs 10%; p = 0.024) and incomplete rectal evacuation (<55% of barium neostool expelled, 50% vs 20%; p = 0.02).

LIMITATIONS

: This study was limited by the retrospective analysis of prospectively collected data.

CONCLUSIONS

Only one-third of incontinent men had sphincteric dysfunction. Other pathophysiologies must therefore be considered. Nearly half of patients reported concurrent constipation, and one-sixth had rectal hyposensitivity, which was associated with higher frequencies of both symptomatic and objective measures of rectal evacuatory dysfunction. In the majority of adult males, fecal incontinence may represent a secondary phenomenon.

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.

What is necessary to diagnose constipation?

Constipation is a common ailment with multiple symptoms and diverse etiology. Understanding the pathophysiology is important to guide optimal management. During the past few years, there have been remarkable developments in the diagnosis of constipation and defecation disorders. Several innovative manometric, neurophysiologic, and radiologic techniques have been discovered, which have improved the accuracy of identifying the neuromuscular mechanisms of chronic constipation. These include use of digital rectal examination, Bristol stool scale, colonic scintigraphy, wireless motility capsule for assessment of colonic and whole gut transit, high resolution anorectal manometry, and colonic manometry. These tests provide a better definition of the underlying mechanism(s), which in turn can lead to improved management of this condition. In this review, we summarize the recent advances in diagnostic testing with a particular emphasis on when and why to test, and discuss the utility of diagnostic tests for chronic constipation.

The Long-term Clinical Efficacy of Biofeedback Therapy for Patients With Constipation or Fecal Incontinence

BACKGROUND/AIMS

There has been a controversy regarding the usefulness of biofeedback therapy for functional constipation or fecal incontinence. This study was performed to investigate the long-term clinical efficacy of biofeedback therapy.

METHODS

Sixty-four patients with constipation or fecal incontinence received biofeedback therapy for 4 weeks. Symptom improvements were evaluated immediately after the completion of biofeedback therapy and during the follow-up period of about 12 to 64 months.

RESULTS

Twenty-five patients in the constipation group [mean age of 52.1 years, 16 men (64.0%)] received 6.2 sessions of biofeedback therapy. Improvement of constipation after the completion of biofeedback therapy was as follows: major response (or improvement) in 3 patients (12.0%), fair in 6 (24.0%), minor in 11 (44.0%) and none in 5 (20.0%). Among 9 patients who showed major or fair improvement, 8 patients (88.9%) maintained the symptom improvement through the long term follow-up periods. Thirty-nine patients in the fecal incontinence group [59.7 years old, 15 men (38.5%)] received 6.8 sessions of biofeedback therapy. Improvement of incontinence after the completion of biofeedback therapy was as follows: major improvement in 6 patients (15.4%), fair in 14 (35.9%), minor in 14 (35.9%), and none in 5 (12.8%). All 11 patients with major or fair improvement maintained the symptom improvement to the end of follow-up periods.

CONCLUSIONS

Symptom improvements after biofeedback therapy were disappointing in both the constipation and incontinence group. However, when the symptom improvements were classified as major or fair, the improvements continued for at least a year.

Sacral nerve modulation in the treatment of fecal incontinence following repair of rectal prolapse

PURPOSE

Persistent or newly-diagnosed fecal incontinence following surgical repair of rectal prolapse has been reported in up to 30% of all treated patients. This study tried to evaluate the role of sacral nerve modulation as a potential treatment for this problem.

PATIENTS AND METHODS

The medical records of 11 patients (all female; median age, 59 years) in 2 coloproctology centers were retrospectively analyzed. All of the patients had been treated for fecal incontinence by sacral nerve modulation, following transabdominal or transanal repair of rectal prolapse. After a median history of 36 (11-72) months following surgery, patients complained about fecal incontinence (median Cleveland Clinic Incontinence Score, 15 (13-20)), and sacral nerve modulation was proposed. The effect of sacral nerve modulation on the Cleveland score, as well as on the quality of life scoring system of The American Society of Colon and Rectal Surgeons, was evaluated.

RESULTS

Based on their continence diaries, 9 of 11 patients reported an improvement of their fecal incontinence during the screening period, and proceeded to a permanent implant. After a median follow-up time of 36 (12-72) months, fecal incontinence scores dropped from a median of 15 (13-20) preoperatively to a median of 5 (3-7) in all implanted patients (P < .01). Quality of life analysis for all implanted patients showed significant improvement in all 4 domains (lifestyle, coping behavior, depression, and embarrassment (P < .01)).

CONCLUSION

In this series, with a limited number of patients, sacral nerve modulation has shown a positive effect on the treatment of both persistent and newly-reported fecal incontinence after surgical repair of rectal prolapse.

Pathophysiology of evacuation disorders

This review details our contemporary knowledge of the mechanisms underlying evacuatory disorders. There is confusion concerning terminology and classification, which is based upon both an incomplete understanding of the multiple mechanisms involved in evacuation, and that current tests to investigate it are not physiological. Nevertheless, despite the need for more research, significant advances have been made and current assessments can direct therapy.

Pathophysiology of colonic causes of chronic constipation

Colonic sensorimotor dysfunction is recognized as the principal pathophysiological mechanism underpinning chronic constipation. This review addresses current understanding derived from both human and animal studies, with particular reference made to methods of investigation.

Visceral afferents - determinants and modulation of excitability

An essential property of visceral sensory afferents is to be able to alter their firing properties in response to changes in the microenvironment at the level of the sensory ending. Significant progress has been made in recent years in understanding the ionic mechanisms of the regulation of afferent neuronal excitability, and in identifying the mechanisms by which this can be altered. This article will review some of the recent developments in the state of knowledge regarding mechanisms of increased excitability after inflammation, and pharmacological modulation of excitability, concentrating on afferent nerves innervating the GI tract and urinary bladder.