Human studies of anorectal sensory function

Rectal sensory-motor alterations: a clinical perspective on anorectal disorders. The correlation between rectal sensation and motility in different anorectal diseases

BACKGROUND

Patients with anorectal diseases commonly exhibit abnormalities in rectal sensation and/or rectal motility. However, the relationship between rectal sensation and motility in these pathological processes is unclear. We aim to explore this association.

METHODS

We conducted a retrospective review of clinical data from 954 patients with anorectal disorders and defecation problems who had undergone anorectal functional testing. We investigated the correlation between rectal sensation and motility across various conditions and assessed the impact of physiological factors.

RESULTS

Significant rectal sensation differences were seen across constipation, fecal incontinence, rectal cancer, and postoperative patients, with the highest sensitivity in postoperative patients (P<0.05). Stratified analysis showed constipated patients with rectal hyposensitivity had higher anal resting and maximum squeeze pressures, lower rectoanal gradients, manometric defecation index, and anal relaxation rate (P<0.05). Further analysis revealed that rectal sensory parameters in constipated patients positively correlated with anal resting and maximum squeeze pressures, and negatively correlated with rectoanal gradients, manometric defecation index, and anal relaxation rate (P<0.05), with the influence of age and gender being synergistic (P<0.05). In rectal cancer, the maximum tolerable volume positively correlates with anal resting pressure and negatively with the rectoanal gradient and manometric defecation index (P<0.05). This negative correlation is also observed in postoperative patients (P<0.05).

CONCLUSIONS

In patients with anorectal disorders and defecation problems, there is a significant correlation between rectal sensory abnormalities and dynamic changes induced by varying levels of rectal sensitivity, with these changes being modulated by physiological factors.

Understanding the physiology of human defaecation and disorders of continence and evacuation

The act of defaecation, although a ubiquitous human experience, requires the coordinated actions of the anorectum and colon, pelvic floor musculature, and the enteric, peripheral and central nervous systems. Defaecation is best appreciated through the description of four phases, which are, temporally and physiologically, reasonably discrete. However, given the complexity of this process, it is unsurprising that disorders of defaecation are both common and problematic; almost everyone will experience constipation at some time in their life and many will develop faecal incontinence. A detailed understanding of the normal physiology of defaecation and continence is critical to inform management of disorders of defaecation. During the past decade, there have been major advances in the investigative tools used to assess colonic and anorectal function. This Review details the current understanding of defaecation and continence. This includes an overview of the relevant anatomy and physiology, a description of the four phases of defaecation, and factors influencing defaecation (demographics, stool frequency/consistency, psychobehavioural factors, posture, circadian rhythm, dietary intake and medications). A summary of the known pathophysiology of defaecation disorders including constipation, faecal incontinence and irritable bowel syndrome is also included, as well as considerations for further research in this field.

Diagnosis of Functional Gastrointestinal Disorders and Choice of Treatment Regimen in Constipation Patients

Aim. A practical review of functional gastrointestinal disorder diagnosis in constipation patients and the rationale for opting treatment.

Key points. Functional constipation commonly afflicts different ages and negatively impacts the quality of life. The current diagnostic algorithm in chronic constipation includes the disease identification according to Rome Criteria IV, red-flag symptom detection and instrumental laboratory examination. Functional constipation is notably often associated with anorectal abnormalities that bear a diagnostic value to elaborate an apt treatment strategy. Anorectal manometry, rectal sensation and balloon expulsion tests are the well-studied and significant probing techniques for objective anorectal zone sensorimotor function assessment in patients with functional constipation. The article reviews modern diagnostic methods in functional defecation disorders.

Conclusion. The examination and treatment algorithms presented will help improve diagnosis and apply the most suitable management in a constipation-associated functional digestive pathology.

Diagnostics of functional disorders of the gastrointestinal tract in patients with constipation

The purpose of the review is to acquaint general practitioners, therapists, gastroenterologists with the possibilities of diagnosing functional disorders of the gastrointestinal tract associated with constipation, as well as to draw attention to the need for additional examination methods for a comprehensive assessment of functional disorders of the gastrointestinal tract in patients with constipation on pathogenesis.

Functional constipation is an urgent problem today due to its prevalence among different age groups, a negative impact on the quality of life, as well as the variability of the clinical forms of diseases associated with this symptom. The modern diagnostic algorithm for chronic constipation consists of several stages, including the identification of signs of the disease, according to the Rome criteria of the IV revision (2016), the identification of symptoms of “red flags” and laboratory and instrumental research. It should be borne in mind that functional constipation is often based on the pathology of the anorectal zone, which is an important factor in the diagnosis and development of further therapeutic strategies. The article provides an overview of modern and promising methods for diagnosing functional disorders of defecation, taking into account functional disorders of the anorectal zone associated with constipation.

Functional methods such as anorectal manometry, rectal sensory test and balloon expulsion test are the  most studied and obligatory tests for an objective assessment of the sensorimotor function of the anorectal zone. In Russia, these methods are used very little, which requires extensive familiarization of practitioners with the advantages of these techniques. Knowledge and application of the presented examination algorithms will help the clinician to increase the overall diagnostic efficiency and apply the most justified tactics of managing patients with functional pathology of the digestive system associated with constipation. 

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.

Kegel Exercises, Biofeedback, Electrostimulation, and Peripheral Neuromodulation Improve Clinical Symptoms of Fecal Incontinence and Affect Specific Physiological Targets: An Randomized Controlled Trial

Background/Aims

Fecal incontinence (FI) is a prevalent condition among community-dwelling women, and has a major impact on quality of life (QoL). Research on treatments commonly used in clinical practice—Kegel exercises, biofeedback, electrostimulation, and transcutaneous neuromodulation—give discordant results and some lack methodological rigor, making scientific evidence weak. The aim is to assess the clinical efficacy of these 4 treatments on community-dwelling women with FI and their impact on severity, QoL and anorectal physiology.

Methods

A randomized controlled trial was conducted on 150 females with FI assessed with anorectal manometry and endoanal ultrasonography, and pudendal nerve terminal motor latency, anal/rectal sensory-evoked-potentials, clinical severity, and QoL were determined. Patients were randomly assigned to one of the following groups Kegel (control), biofeedback + Kegel, electrostimulation + Kegel, and neuromodulation + Kegel, treated for 3 months and re-evaluated, then followed up after 6 months.

Results

Mean age was 61.09 ± 12.17. Severity of FI and QoL was significantly improved in a similar way after all treatments. The effect on physiology was treatment-specific Kegel and electrostimulation + Kegel, increased resting pressure (P < 0.05). Squeeze pressures strongly augmented with biofeedback + Kegel, electrostimulation + Kegel and neuromodulation + Kegel (P < 0.01). Endurance of squeeze increased in biofeedback + Kegel and electrostimulation + Kegel (P < 0.01). Rectal perception threshold was reduced in the biofeedback + Kegel, electrostimulation + Kegel, and neuromodulation + Kegel (P < 0.05); anal sensory-evoked-potentials latency shortened in patients with electrostimulation + Kegel (P < 0.05).

Conclusions

The treatments for FI assessed have a strong and similar efficacy on severity and QoL but affect specific pathophysiological mechanisms. This therapeutic specificity can help to develop more efficient multimodal algorithm treatments for FI based on pathophysiological phenotypes.