Rectal hyposensitivity: evaluation of anal sensation in female patients with refractory constipation with and without faecal incontinence

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.

Comparison of Anorectal Manometry, Rectal Balloon Expulsion Test, and Defecography for Diagnosing Defecatory Disorders

BACKGROUND & AIMS

The utility of high-resolution anorectal manometry (HR-ARM) for diagnosing defecatory disorders (DDs) is unclear because healthy people may have features of dyssynergia. We aimed to identify objective diagnostic criteria for DD and to ascertain the utility of HR-ARM for diagnosing DD.

METHODS

Constipated patients were assessed with HR-ARM and rectal balloon expulsion time (BET), and a subset underwent defecography. Normal values were established by assessing 184 sex-matched healthy individuals. Logistic regression models evaluated the association of abnormal HR-ARM findings with prolonged BET and reduced rectal evacuation (determined by defecography).

RESULTS

A total of 474 constipated individuals (420 women) underwent HR-ARM and BET, and 158 underwent defecography. BET was prolonged, suggesting a DD, for 152 patients (32%). Rectal evacuation was lower for patients with prolonged vs normal BET. A lower rectoanal gradient during evacuation, reduced anal squeeze increment, and reduced rectal sensation were independently associated with abnormal BETs; the rectoanal gradient was 36% sensitive and 85% specific for prolonged BET. A lower rectoanal gradient and prolonged BET were independently associated with reduced evacuation. Among constipated patients, the probability of reduced rectal evacuation was 14% when the gradient and BET were both normal, 45% when either was abnormal, and 75% when both variables were abnormal.

CONCLUSIONS

HR-ARM, BET, and defecography findings were concordant for constipated patients, and reduced rectoanal gradient was the best HR-ARM predictor of prolonged BET or reduced rectal evacuation. Prolonged BET, reduced gradient, and reduced evacuation each independently supported a diagnosis of DD in constipated patients. We propose the terms probable DD for patients with an isolated abnormal gradient or BET and definite DD for patients with abnormal results from both tests.

The puborectal continence reflex functions independently of the pudendal nerve

AIM

The ability of patients with poor pudendal nerve function to voluntarily contract their external anal sphincter is limited. However, it is not known whether the condition of the pudendal nerve influences voluntary puborectal muscle contraction. Recently, we described the puborectal continence reflex that maintains faecal continence by involuntary contractions of the puborectal muscle. We aim to investigate whether both voluntary and involuntary contractions of the puborectal muscle are influenced by the condition of the pudendal nerve.

METHOD

We retrospectively analysed 129 adult patients who underwent anorectal function tests at the Anorectal Physiology Laboratory. Anal electrosensitivity was used as a measurement of the pudendal nerve function. Voluntary and involuntary contractions of the puborectal muscle were defined as maximum puborectal muscle contractility and maximum pressure at the level of the puborectal muscle during the balloon retention test.

RESULTS

Voluntary contraction of the puborectal muscle was significantly decreased in patients with pudendal nerve damage (P = 0.002). Involuntary contractions, however, were not associated with the condition of the pudendal nerve (P = 0.63). Multiple linear regression analysis showed that the condition of the pudendal nerve and patients' sex significantly predicted voluntary contraction but not involuntary contraction.

CONCLUSION

Voluntary contractions of the puborectal muscle are significantly decreased in patients with pudendal nerve damage, while involuntary contractions of the puborectal muscle are comparable to those of patients without nerve damage. We conclude that the puborectal continence reflex, which controls involuntary contractions of the puborectal muscle, is not regulated by the pudendal nerve.

Human studies of anorectal sensory function

This review addresses three main questions: (1) Why is anorectal sensory function important in humans? (2) What is the evidence for anorectal sensory dysfunction in disease? (3) Can anorectal sensory function be modified for therapeutic benefit?

Searching for a definition for pharmacologically refractory constipation: A systematic review

BACKGROUND AND AIM

Surgery and other non-pharmacological treatments such as sacral nerve stimulation are used for the treatment of difficult-to-treat chronic constipation. Novel pharmacological therapeutic agents are also being introduced. To evaluate the efficacy of these treatments, it is imperative to have a consistent definition of pharmacologically refractory constipation. A systematic review of studies on refractory, difficult-to-treat or surgically treated constipation was carried out to determine the criteria that various authors used to define this group of patients.

METHODS

A systematic review was performed for literature published from June 2005 to June 2015 using PubMed, Cochrane, and Scopus databases, as well as manual searches. Studies on patients with refractory or intractable constipation were extracted. Criteria used for defining refractory constipation, as well as pharmacological agents tried including dosage, frequency, and duration, were reviewed.

RESULTS

Sixty-one studies were included in this review. Forty-eight involved surgical treatment of constipation, while 13 examined non-surgical therapies for refractory constipation. There is no generally accepted definition of refractory constipation. Authors consider constipation to be refractory when response to management is suboptimal, but there is no consensus on the choice of drug, order of usage, and dosage or treatment duration. Prior medical therapy was not mentioned at all in five studies.

CONCLUSIONS

There is need for a detailed definition of pharmacologically refractory constipation before submitting patients to invasive treatments and to evaluate new pharmacological agents.

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.

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.

A bi-directional assessment of the human brain-anorectal axis

BACKGROUND

Brain-gut dysfunction has been implicated in gastrointestinal disorders but a comprehensive test of brain-gut axis is lacking. We developed and tested a novel method for assessing both afferent anorectal-brain function using cortical evoked potentials (CEP), and efferent brain-anorectal function using motor evoked potentials (MEP).

METHODS

Cortical evoked potentials was assessed following electrical stimulations of anus and rectum with bipolar electrodes in 26 healthy subjects. Anorectal MEPs were recorded following transcranial magnetic stimulation (TMS) over paramedian motor cortices bilaterally. Anal and rectal latencies/amplitudes for CEP and MEP responses and thresholds for first sensation and pain (mA) were analyzed and compared. Reproducibility and interobserver agreement of responses were examined.

KEY RESULTS

Reproducible polyphasic rectal and anal CEPs were recorded in all subjects, without gender differences, and with negative correlation between BMI and CEP amplitude (r -0.66, P=0.001). Transcranial magnetic stimulation evoked triphasic rectal and anal MEPs, without gender differences. Reproducibility for CEP and MEP was excellent (CV <10%). The inter-rater CV for anal and rectal MEPs was excellent (ICC 97-99), although there was inter-subject variation.

CONCLUSIONS & INFERENCES

Combined CEP and MEP studies offer a simple, inexpensive and valid method of examining bidirectional brain-anorectal axes. This comprehensive method could provide mechanistic insights into lower gut disorders.

[Diagnosis of constipation: a systematic review]

To diagnose constipation accurately in self-reported constipated patients is very important not to miss organic disease and prevent therapeutic abuse. To investigate the etiology of functional constipation is also important to determine the therapeutic modality of constipation. In this systemic review, the clinical usefulness of symptom evaluation, diagnostic tests to rule out organic and systemic disease, and functional tests to discriminate underlying pathophysiology in the diagnosis of constipation were discussed. No specific symptoms or tests were available to predict organic versus functional constipation or differentiate slow transit constipation versus evacuation disorder. Therefore, collaborative studies are necessary to determine the pathophysiology of this disorder.

Discriminative value of anorectal manometry in clinical practice

Guidelines recommend anorectal manometry in patients with fecal incontinence and chronic constipation. However, limited evidence supports the utility of manometric testing. We retrospectively reviewed tracings obtained between November 2005 and May 2008. A total of 298 patients (86% women; average age 52 years) were included. The main indications were incontinence (51%) and constipation (42%). Patients suffering from incontinence were older and had lower resting and squeeze pressure compared to continent patients. However, the discriminative power of manometric pressure data was poor, with low sensitivity and specificity. An abnormal straining pattern suggesting dyssynergic defecation was seen in 43% of constipated patients compared to 13% of patients with fecal incontinence. A concordance between manometric patterns and the balloon expulsion test was seen in 72%. The low sensitivity and specificity of manometric parameters does not support the routine use of anorectal manometry in patients with defecation disorders.

Manometric, sensorimotor, and neurophysiologic evaluation of anorectal function

With advances in diagnostic technology, it is now accepted that in the field of functional bowel disorders, symptom-based assessment is unsatisfactory as the sole means of directing therapy. A robust taxonomy based on underlying pathophysiology has been suggested, highlighting a crucial role for physiologic testing in clinical practice. A wide number of complementary investigations currently exist for the assessment of anorectal structure and function, some of which have a clinical impact in patients with functional disorders of evacuation and continence by markedly improving diagnostic yield and altering management. The techniques, limitations, measurements, and clinical use of manometric, sensorimotor, and neurophysiologic tests of anorectal function are presented.