Novel insights into physiological mechanisms underlying fecal continence.

The machinery maintaining fecal continence prevents involuntary loss of stool and is based on the synchronized interplay of multiple voluntary and involuntary mechanisms, dependent on cooperation between motor responses of the musculature of the colon, pelvic floor, and anorectum, and sensory and motor neural pathways. Knowledge of the physiology of fecal continence is key toward understanding the pathophysiology of fecal incontinence. The idea that involuntary contraction of the internal anal sphincter is the primary mechanism of continence and that the external anal sphincter supports continence only by voluntary contraction is outdated. Other mechanisms have come to the forefront, and they have significantly changed viewpoints on the mechanisms of continence and incontinence. For instance, involuntary contractions of the external anal sphincter, the puborectal muscle, and the sphincter of O'Beirne have been proven to play a role in fecal continence. Also, retrograde propagating cyclic motor patterns in the sigmoid and rectum promote retrograde transit to prevent the continuous flow of content into the anal canal. With this review, we aim to give an overview of primary and secondary mechanisms controlling fecal continence and evaluate the strength of evidence.

Preclinical applications of high-definition manometry system to investigate pelvic floor muscle contribution to continence mechanisms in a rabbit model.

External anal sphincter (EAS), external urethral sphincters, and puborectalis muscle (PRM) have important roles in the genesis of anal and urethral closure pressures. In the present study, we defined the contribution of these muscles alone and in combination with the sphincter closure function using a rabbit model and a high-definition manometry (HDM) system. A total of 12 female rabbits were anesthetized and prepared to measure anal, urethral, and vaginal canal pressures using a HDM system. Pressure was recorded at rest and during electrical stimulation of the EAS and PRM. A few rabbits (n = 6) were subjected to EAS injury and the impact of EAS injury on the closure pressure profile was also evaluated. Anal, urethral, and vaginal canal pressures recorded at rest and during electrical stimulation of EAS and PRM demonstrated distinct pressure profiles. EAS stimulation induced anal canal pressure increase, whereas PRM stimulation increased the pressures in all the three orifices. Electrical stimulation of EAS after injury resulted in about 19% decrease in anal canal pressure. Simultaneous electrical stimulation of EAS and PRM resulted in an insignificant increase of individual anal canal pressures when compared with pressures recorded after EAS or PRM stimulations alone. Our data confirm that HDM is a viable system to measure dynamic pressure changes within the three orifices and to define the role of each muscle in the development of closure pressures within these orifices in preclinical studies.NEW & NOTEWORTHY We anticipate that with this new HDM technology, physiological changes within these orifices may be redefined using the extensive data that are generated from 96 sensors. When compared with conventional methods, HDM offers the advantages of an increased response rate, as well as the utilization of 96 circumferential sensors to simultaneously measure pressure along the three orifices. Our findings suggest a potential use of this technology to better define urinary leak point pressure.

Functional Outcomes and Quality of Life After Transanal Total Mesorectal Excision for Rectal Cancer: A Prospective Observational Study.

BACKGROUND: Few studies have addressed the functional impact after transanal total mesorectal excision. OBJECTIVE: This study aimed to evaluate function and health-related quality of life among patients with rectal cancer treated with transanal total mesorectal excision. DESIGN: Consecutive patients treated between 2016 and 2018 were selected. Their function and quality of life were studied preoperatively and at 3 and 12 months after surgery. SETTING: This is a prospective case series. PATIENTS: Patients were eligible if they had primary anastomosis, their diverting stoma had been reversed, and they did not have anastomotic leakage. Forty-five patients were finally included. A total of 31 (68.8%) and 32 patients (71.1%) completed the 3- and 12-month surveys. INTERVENTIONS: Standard transanal total mesorectal excision was performed. MAIN OUTCOME MEASURES: The primary end point was functional and quality-of-life outcomes using validated questionnaires. Secondary end points included values obtained with endoanal ultrasounds, anorectal manometries, and rectal sensation testing. RESULTS: Wexner and Low Anterior Resection Syndrome scores significantly increased 3 months after surgery but returned to baseline values at 12 months. The rate of "major low anterior resection syndrome" at the end of follow-up was 25.0% (+11.7% compared with baseline, p = 0.314). Sexual and urinary functions remained stable throughout the study, although a meaningful clinical improvement was detected in male sexual interest. Among quality-of-life domains, all deteriorations returned to baseline values 12 months after surgery, except worsening of flatulence symptoms, and improvement in insomnia and constipation. At 12 months, an expected decrease in the mean width of the internal sphincter, the anal resting pressure, and the tenesmus threshold volume was found. LIMITATIONS: This study was limited by its small sample size, the absence of a comparative group, and significant missing data in female sexual difficulty and in ultrasounds and manometries at 3 months. CONCLUSIONS: Patients undergoing transanal total mesorectal excision report acceptable quality-of-life and functional outcomes 12 months after surgery. See Video Abstract at http://links.lww.com/DCR/B541. RESULTADOS FUNCIONALES Y CALIDAD DE VIDA DE LOS PACIENTES DESPUS DE LA ESCISIN MESORRECTAL TOTAL TRANSANAL PARA CNCER DE RECTO UN ESTUDIO PROSPECTIVO OBSERVACIONAL: ANTECEDENTES:Pocos estudios han abordado el impacto funcional después de la escisión mesorrectal total transanal.OBJETIVO:Evaluar la función y la calidad de vida relacionada con la salud en pacientes con cáncer de recto tratados con escisión mesorrectal total transanal.DISEÑO:Se seleccionaron pacientes consecutivos tratados entre 2016 y 2018. Se estudió su función y calidad de vida, en la etapa preoperatoria, a los tres y doce meses postoperatorios.METODO:Serie de casos prospectivos.PACIENTES:Los pacientes eran incluidos en presencia de anastomosis primaria, cierre del estoma de derivación y en ausencia de fuga anastomótica. Finalmente se incluyeron cuarenta y cinco pacientes. Un total de 31 (68,8%) y 32 pacientes (71,1%) completaron las encuestas de tres y doce meses, respectivamente.INTERVENCIONES:Escisión mesorrectal total transanal estándar.PRINCIPALES MEDIDAS DE RESULTADO:Los criterio de evaluación principal fueron los resultados funcionales y de calidad de vida mediante cuestionarios previamente validados. Los criterios de evaluación secundarios incluyeron los valores obtenidos con ecografía endoanal, manometría anorrectal y prueba de sensibilidad rectal.RESULTADOS:La escala de Wexner y el síndrome de resección anterior baja aumentaron significativamente tres meses después de la cirugía, pero volvieron a los valores iniciales a los doce meses. La tasa de "síndrome de resección anterior inferior grave" al final del seguimiento fue del 25,0% (+ 11,7% en comparación con el valor inicial, p = 0,314). La función sexual y urinaria se mantuvo estable durante todo el estudio, aunque se detectó una mejora clínica significativa en la libido masculina. Entre los criterios que evalúan la calidad de vida, todas las alteraciones en la misma volvieron a los valores iniciales, doce meses después de la cirugía, excepto el aumento de flatulencia, la mejoría del insomnio y el estreñimiento. A los doce meses, se encontró una disminución esperada en el grosor medio del esfínter interno, la presión anal en reposo y el volumen umbral para la presencia de tenesmo.LIMITACIONES:Tamaño de muestra limitado, ausencia de un grupo comparativo, falta significativa de datos para identificar la dificultad para la actividad sexual femenina y el efectuar ecografía y manometría a los tres meses.CONCLUSIONES:Los pacientes sometidos a escisión mesorrectal total transanal refieren una calidad de vida y resultados funcionales aceptables a los doce meses después de la cirugía. Consulte Video Resumen en http://links.lww.com/DCR/B541.

[Analysis of anorectal manometry data in central and peripheral neurological deseases: Review of the literature]. / Analyse des données de manométrie ano-rectale dans les pathologies neurologiques centrales et périphériques : revue de la littérature.

INTRODUCTION: Peripheral or central neurological deseases are providers of anorectal disorders of variable clinical expression (constipation, dyschezia, faecal incontinence (FI)…). Anorectal manometry (ARM) participates in their exploration to determine the underlying mechanisms, guide and optimize treatments. The objective of this work was to determine if there is a pattern of ARM data in neurological populations. MATERIALS ET METHODS: Literature review from PubMed, Cochrane and Google scholar databases, using the following keywords: parkinsonian disorders; parkinson's disease; multiple slcerosis; neurolog*; spinal cord injury; spina bifida occulta; stroke; pudendal; endometriosis; peripheral nervous system diseases. 196 articles were isolated and finally 45 retained after reading the title and the abstract. RESULTS: Data comparison was difficult due to the heterogeneity of techniques and thresholds used. In central lesions, resting and squeeze anal pressures were often altered. The presence of FI or constipation, the sex and the lesion level were factors influencing these data (low if complete injury, women or EDSS>5.5). In case of peripheral lesion, it is the anal tone and the contraction that varied the symptomatology. The sensory thresholds were variable regardless of the impairment. CONCLUSION: This review did not identify a data pattern of ARM in central and peripheral neurological deseases. Gradual standardization of techniques and protocols will allow better comparison of data.

Fatigability of the external anal sphincter muscles using a novel strength training resistance exercise device.

Exercises involving pelvic floor muscles including repetitive voluntary contractions of external anal sphincter (EAS) musculature have been used to improve fecal incontinence. Muscle fatigue is a prerequisite for successful strength training. However, muscle fatigue induced by these exercises has not been systematically studied. We aimed to assess the fatigability of EAS muscles during various exercise methods. Twelve nulliparous (21 ± 2.7 yr) women were studied. We evaluated fatigue during 40 repetitive 3-s contractions and 30-s long squeeze contractions both with and without an intra-anal compressible resistant load. The sequence of exercises was randomized. This load was provided by the continence muscles Resistance Exerciser Device. Anal canal pressures were recorded by high-resolution manometry. Exercise against a resistive load showed significant decrease in anal contractile integral (CI) and maximum squeeze pressure during repetitive short squeeze contractions compared with exercise without a load. Linear regression analysis showed a significant negative correlation between anal CI and successive contraction against load, suggesting "fatigue." Similar findings were observed for maximum squeeze pressure (slope with load = -4.2, P = 0.0003, vs. without load = -0.9, P = 0.3). Long squeeze contraction against a load was also more susceptible to fatigue than without a load (P < 0.0001). In conclusion, repetitive contractions against a compressible load induce fatigue and thus have the potential to strengthen the anal sphincter contractile function than contractions without a load. Fatigue rate in long squeeze contraction exercises with a load is significantly faster than that without a load, also indicating greater effectiveness in inducing muscle fatigue.NEW & NOTEWORTHY Fecal incontinence is a distressing disorder with a mainstay of treatment being pelvic floor muscle exercises. However, none of these exercises has proven occurrence of fatigability, which is an important prerequisite for successful muscle strengthening in rehabilitative exercises. In this study, we proved that we can fatigue the external anal sphincter muscles more efficiently by providing a resistive load during anal repetitive short squeeze contractions and long squeeze contraction exercise.

Simulated stool for assessment of anorectal physiology.

Fecal continence is maintained by several mechanisms including anatomical factors, anorectal sensation, rectal compliance, stool consistency, anal muscle strength, mobility, and psychological factors. The homeostatic balance is easily disturbed, resulting in symptoms including fecal incontinence and constipation. Current technologies for assessment of anorectal function have limitations. Overlap exist between data obtained in different patient groups, and there is lack of correlation between measurements and symptoms. This review describes a novel technology named Fecobionics for assessment of anorectal physiology. Fecobionics is a simulated stool, capable of dynamic measurements of a variety of variables during defecation in a single examination. The data facilitate novel analysis of defecatory function as well as providing the foundation for modeling studies of anorectal behavior. The advanced analysis can enhance our physiological understanding of defecation and future interdisciplinary research for unraveling defecatory function, anorectal sensory-motor disorders, and symptoms. This is a step in the direction of improved diagnosis of anorectal diseases.

Fecal Continence for Solid and Liquid Stool: The Function of the Anal-External Sphincter Continence Reflex and the Puborectal Continence Reflex.

BACKGROUND: The anal-external sphincter continence reflex and the puborectal continence reflex control fecal continence by involuntary contractions of the external anal sphincter and puborectal muscle. To date it is unknown what the effect of liquid stool is on these reflexes. OBJECTIVE: The purpose of this study was to analyze the consequence of liquid stool on the presence and function of these fecal continence reflexes. DESIGN: This was a prospective, observational study. SETTING: The study was conducted at the Anorectal Physiology Laboratory, University Medical Center Groningen. PATIENTS: Forty-two healthy subjects were included. MAIN OUTCOME MEASURES: Pressure changes at the level of the external anal sphincter and the puborectal muscle during the anorectal pressure test used to measure voluntary contractions, the balloon retention test used to measure involuntary contractions mimicking solid stool, and the rectal infusion test used to investigate the effect of only water mimicking liquid stool were measured. RESULTS: During the test mimicking solid stool, the pressure at the level of the external anal sphincter increased from the start to the end (132 ± 54 vs 198 ± 69 mm Hg; p < 0.001). The pressure at the level of the puborectal muscle increased simultaneously (30 ± 9 vs 176 ± 52 mm Hg; p < 0.001). After injecting water into the rectum, mimicking liquid stool, we observed immediate activation of the anal-external sphincter continence reflex (87 ± 32 vs 145 ± 36 mm Hg; p < 0.001); this was after a median 30 seconds, whereas no activation of the puborectal continence reflex appeared (26 ± 9 vs 26 ± 7 mm Hg; p = 0.655). LIMITATIONS: We only performed anorectal function tests mimicking 2 types of stool consistencies, namely water and solid. CONCLUSIONS: The anal-external sphincter continence reflex controls fecal continence of both solid and liquid stool. Contrarily, the puborectal continence reflex contributes to solid stool continence only. See Video Abstract at http://links.lww.com/DCR/B286. CONTINENCIA FECAL PARA HECES SÓLIDAS Y LÍQUIDAS: LA FUNCIÓN DEL REFLEJO DE CONTINENCIA DEL ESFÍNTER ANAL EXTERNO Y EL REFLEJO DE CONTINENCIA PUBORRECTAL: El reflejo de continencia del esfínter anal externo y el reflejo de continencia puborrectal controlan la continencia fecal mediante contracciones involuntarias del esfínter anal externo y el músculo puborrectal, respectivamente. Hasta la fecha, se desconoce cuál es el efecto de las heces líquidas en estos reflejos.Analizar las consecuencias de las heces líquidas en la presencia y función de estos reflejos de continencia fecal.Estudio prospectivo observacional.Laboratorio de F fisiología anorrectal, University Medical Center Groningen.Cuarenta y dos sujetos sanos.Los cambios de presión a nivel del esfínter anal externo y el músculo puborrectal durante la prueba de presión anorrectal utilizada para medir las contracciones voluntarias, la prueba de retención con balón utilizada para medir las contracciones involuntarias que imitan las heces sólidas, y la prueba de infusión rectal utilizada para investigar El el efecto de solo agua imitando las heces líquidas.Durante la prueba que imita las heces sólidas, la presión a nivel del esfínter anal externo aumentó desde el principio hasta el final (132 ± 54 mm Hg versus 198 ± 69 mm Hg, p <0.001). La presión a nivel del músculo puborrectal aumentó simultáneamente (30 ± 9 mm Hg versus 176 ± 52 mm Hg, p <0,001).Después de inyectar agua en el recto, imitando las heces líquidas, observamos la activación inmediata del AESCR (87 ± 32 mm Hg versus 145 ± 36 mm Hg, p <0.001), esto fue después de una mediana de 30 segundos, mientras que no hubo activación de la continencia puborrectal apareció reflejo (26 ± 9 mm Hg versus 26 ± 7 mm Hg, p = 0,655).Solo realizamos pruebas de función anorrectal que imitan dos tipos de consistencia de heces, a saber, discriminando entre a agua y sólidos.El reflejo de continencia del esfínter anal-externo controla la continencia fecal de las heces sólidas y líquidas. Por el contrario, el reflejo de continencia puborrectal contribuye solo a la continencia de heces sólidas. Consulte Video Resumen en http://links.lww.com/DCR/B286. (Traducción-Dr Adrian Ortega).

Reliability of manometry for assessing pelvic floor muscle function in healthy men.

OBJECTIVES: To the best of our knowledge, no study has examined the reliability of assessment methods for male pelvic floor muscle (PFM) function. Therefore, this study aimed to clarify the reliability of manometry with an anal sensor (Peritron cat 9300A) to assess PFM function in healthy men. METHODS: Healthy male subjects (n = 21) without urinary leakage underwent testing to assess PFM function, and intra- and interrater reliability tests among examiners were performed. The PFM function included maximal anorectal squeeze pressure, endurance, mean anorectal squeeze pressure, gradient, and area under the curve during PFM voluntary contraction. RESULTS: Participants had a median age of 38 years (range 26-51), and a mean BMI of 23.2 ± 2.0 kg/m2 . Satisfactory intra- and interrater reliability scores were found for resting pressure, anorectal squeeze pressure, and endurance. The intra-rater reliability of resting pressure, anorectal squeeze pressure, and endurance were 0.71, 0.89, and 0.75 for examiner 1 and 0.72, 0.89, and 0.87 for examiner 2. The interrater reliability for resting pressure, anorectal squeeze pressure, and endurance were 0.58, 0.93, and 0.61, respectively. CONCLUSIONS: This is the first prospective study showing the favorable intra- and interrater reliability of manometry for PFM function in healthy men. Our findings demonstrated that manometry can provide both reliable and reproducible data regarding PFM function in continent men, suggesting Peritron cat 9300A can be used to evaluate the PFM function in men.

The London Classification: Improving Characterization and Classification of Anorectal Function with Anorectal Manometry.

PURPOSE OF REVIEW: Objective measurement of anorectal sensorimotor function is a requisite component in the clinical evaluation of patients with intractable symptoms of anorectal dysfunction. Regrettably, the utility of the most established and widely employed investigations for such measurement (anorectal manometry (ARM), rectal sensory testing and the balloon expulsion test) has been limited by wide variations in clinical practice. RECENT FINDINGS: This article summarizes the recently published International Anorectal Physiology Working Group (IAPWG) consensus and London Classification of anorectal disorders, together with relevant allied literature, to provide guidance on the indications for, equipment, protocol, measurement definitions and results interpretation for ARM, rectal sensory testing and the balloon expulsion test. The London Classification is a standardized method and nomenclature for description of alterations in anorectal motor and sensory function using office-based investigations, adoption of which should bring much needed harmonization of practice.

Design and evaluation of puborectalis-like artificial anal sphincter that replicates rectal perception.

While fecal incontinence (FI) is not fatal, it can dramatically decrease the patient's quality of life. An artificial anal sphincter (AAS) is an implantable device that treats FI by replacing a diseased or damaged anal sphincter, thus allowing the patient's continence to be maintained. Here, we report a novel implantable puborectalis-like artificial anal sphincter (PAAS) that replicates rectal perception and has a low risk of ischemia necrosis. Using the pressure sensors embedded in the PAAS, the relationship between the mass of feces and the pressure was determined, and a feces mass estimation model was developed based on in vitro studies. Rectal perception is provided through the real-time monitoring of rectal feces, and the feeling of defecation is quantified based on a comparison between the feces mass and a preset threshold mass. In vivo studies were performed for validation, and the accuracy of the model was determined to be as high as 90%. The performance of the PAAS in the real-time monitoring of rectal feces and its in vivo biocompatibility were also evaluated. The device should further the functionality of existing AAS systems while improving their biosafety and thus expand the applicability of implantable AAS systems in the treatment of FI.

[Anal tone: Physiology, clinical and instrumental characteristics]. / Tonus anal : déterminant physiologique, évaluation clinique et paraclinique, caractéristique pathologique.

INTRODUCTION: The anal tone allows the maintenance of anorectal continence. Its regulation depends on spinal segmental mechanisms under supra-sacral control. MATERIAL AND METHODS: A systematic review was performed using Medline database, according to PRISMA methodology, using following keywords anal tone ; anal sphincter ; anorectal function ; reflex ; digital rectal examination. RESULTS: Anal hypertonia is an increase in the muscle's resistance to passive stretching. Muscular hypotonia is a decrease in muscle tone. It is associated with a decrease in resistance to passive mobilization. It is not possible to quantify the prevalence of anal tone alterations in the general population and in specific pathological conditions (urinary disorders, neurogenic or non-neurogenic anorectal disorders). In case of hypotonia, most often due to a lower motor neuron lesion, fecal incontinence may occur. Hypertonia (anal sphincter overactivity) is not always due to perineal spasticity. Indeed, in the majority of the cases, the cause of this anal hypertonia in a neurologic context, can be secondary to an upper motor neuron disease due to spinal or encephalic lesion, leading to recto-anal dyssynergia, giving distal constipation. In another way, this anal hypertonia can be purely behavioral, with no direct pathological significance. The evaluation of anal tone is clinical with validated scores but whose sensitivity is not absolute, and instrumental with, on the one hand, the measurement of anal pressure in manometry and, on the other hand, electrophysiological testing which still require validation in this indication. CONCLUSION: Anal tone assessment is of interest in clinical practice because it gives diagnostic arguments for the neurological lesion and its level, in the presence of urinary or anorectal symptoms.

Methodologic Validation of a Faster Pelvic Floor Test: Two Randomized Studies in Anal Acoustic Reflectometry.

BACKGROUND: Anal acoustic reflectometry investigates the opening and closing function of the anal canal using reflected sound waves to measure a cross-sectional area at different pressures. Anal acoustic reflectometry is reliable and repeatable, distinguishes between continence and incontinence and between subgroups of incontinence, correlates with symptom severity, and does not distort the anal canal during investigation. OBJECTIVE: The purpose of this study was to validate anal acoustic reflectometry methodology by asking 2 questions: can anal acoustic reflectometry be used alongside manometry (order study) and can anal acoustic reflectometry be performed faster (filling study). The secondary aim was to assess the response of the anal canal to stretch using anal acoustic reflectometry. DESIGN: This research included 2 prospective randomized studies. SETTINGS: The study was conducted at a tertiary referral center. PATIENTS: Patients undergoing investigation for fecal incontinence were included. INTERVENTION: For the order study, patients were prospectively randomized to anal acoustic reflectometry, manometry, 2-minute rest and then manometry, anal acoustic reflectometry, or vice versa. For the filling study, patients were prospectively randomized to fast rate anal acoustic reflectometry (5 cm H2O/1 s), manometry, 2-minute rest and then manometry, normal rate anal acoustic reflectometry (5 cm H2O/3 s), or vice versa. MAIN OUTCOME MEASURES: The primary outcome was no difference in anal acoustic reflectometry or manometry variables. Demographic and clinical data were recorded. RESULTS: The order study included 30 patients with a median age of 63 years (range, 30-84 y); 77% were women. No difference was found among all of the variables of anal acoustic reflectometry and manometry regardless of which test was performed first. The filling study included 50 patients with a median age of 62 years (range, 30-78 y); 80% were women. No difference was found between fast and normal rates of anal acoustic reflectometry and manometry in any order. LIMITATIONS: This study was limited by its comparison with water-perfused manometry. CONCLUSIONS: Anal acoustic reflectometry and manometry can be performed at the normal or fast rate of anal acoustic reflectometry in any order. A fast rate of anal acoustic reflectometry did not augment the response of the anal canal to stretch as measured by anal acoustic reflectometry and manometry. This study validates a faster anal acoustic reflectometry technique and vindicates previous data. See Video Abstract at http://links.lww.com/DCR/A821.

Neural control properties of the external anal sphincter in young and elderly women.

AIMS: The prevalence of fecal incontinence (FI) increases with age and affects more than 15% of the elderly population. Sarcopenia, skeletal muscle structural, and functional decline with aging, is known to be caused by neuromuscular dysfunction. However, age-related alterations of the neuromuscular function of the external anal sphincter (EAS) have not been studied. This study aims to quantitatively characterize the effect of aging on the EAS by assessing the firing patterns and size of motor unit action potential (MUAP) using high-density surface electromyography (HD-sEMG) recording and analysis techniques. METHODS: Thirteen young (31.0 ± 3.6 years) and 14 elderly (64.3 ± 6.2 years) healthy women were recruited for this study. EMG activity of the EAS during maximal voluntary contraction was recorded by a 64-Channel, HD-sEMG intra-rectal probe. HD-sEMG signals were decomposed into MUAP spike trains to extract the firing rate and amplitudes thereof. RESULTS: HD-sEMG decomposition was successfully performed. For the young and elderly groups, mean motor unit (MU) firing rates of 11.4 ± 2.1 pulses per second (PPS) and 9.6 ± 2.3 PPS, and mean MUAP amplitudes of 45.2 ± 14.3 µV and 61.9 ± 21.2 µV were respectively obtained. Both the MU firing rate and MUAP amplitude were significantly different between two groups (P < .05). Moreover, the MUAP firing rate and amplitude correlated with age with a linear regression model (P < .05). CONCLUSIONS: This study represents the first effort to examine the effect of aging on the neuromuscular function of EAS. Results suggest an age-related impairment of lower motor neuron descending excitation to the EAS with a compensatory increase in mean MU size.

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.

Investigation of Electromyographic Activity of Pelvic Floor Muscles in Different Body Positions to Prevent Urinary Incontinence.

BACKGROUND This study aimed to determine whether trunk stability muscles co-contract with body position as a factor of pelvic floor muscle (PFM) activity. MATERIAL AND METHODS Sixty-one healthy adults without pelvic floor dysfunction were examined for pelvic floor and trunk stability muscle activity in 4 body positions (ankle dorsiflexion and plantar flexion in standing position, and ankle dorsiflexion and plantar flexion in long sitting position). The activities of the PFMs via anal/vaginal probes, internal oblique (IO), multifidus (MF), tibialis anterior, and gastrocnemius muscles were measured by surface electromyography. Three-dimensional motion analysis measured the movement of the pelvis in real time according to the change in body position. RESULTS There was a significant increase in PFM activity from the ankle neutral position while standing for both ankle dorsiflexion and plantar flexion in standing position (p<0.05). In maximal contraction of PFM in the standing position, IO and MF were found to co-activate (p<0.05). CONCLUSIONS In standing position, the ankle dorsiflexion and plantar flexion positions activated PFMs, which was found to co-activate with trunk stability muscles. Pelvic floor training programs based on the results of this study may be helpful in patients with incontinence.

Anti-muscarinic drugs increase rectal compliance and exacerbate constipation in chronic spinal cord injury : Anti-muscarinic drug effect on neurogenic bowel.

STUDY DESIGN: Prospective cohort study OBJECTIVES: We hypothesized that anti-muscarinic agents alter rectal compliance in SCI patients and that altered rectal compliance relates to bowel symptomatology. Our primary aim was to compare rectal compliance before and after the institution of anti-muscarinics (solifenacin and tolterodine) and an adrenoceptor agonist (mirabegron) in these patients. Additionally, we wanted to evaluate if anorectal manometry differed before and after use of anti-muscarinic agents. SETTING: Tertiary neurogastroenterology clinic, London METHODS: Thirty-five patients with supraconal spinal cord injury (SCI) underwent anal manometry, assessment of rectoanal inhibitory reflex (RAIR) and rectal compliance before and after anti-muscarinic treatment (for overactive bladder) was started (mean follow-up 12 weeks). Patients were assessed identically, pre-and post-treatment (solifenacin n = 17, tolterodine n = 10, mirabegron n = 8). Doses used were as for non-SCI patients. RESULTS: Resting, squeeze and cough pressures were unchanged after anti-muscarinic treatment. Rectal compliance was significantly raised after anti-muscarinic treatment (p = 0.001). The percent amplitude of maximal sphincter relaxation of the RAIR was decreased (p < 0.001) and excitation latency was increased (p = 0.006). There was no significant change in the duration of recovery of the RAIR. There was a significant increase of the Wexner Constipation Score (p = 0.001) but no change in the Wexner Incontinence Score. There was a significant correlation between change in rectal compliance and change in Wexner Constipation Score (p = 0.001). Thus, increasing compliance of the rectum is associated with worsening of constipation after anti-muscarinic therapy. However, there were no changes in anorectal manometry or rectal compliance in those who received mirabegron. CONCLUSION: Anti-muscarinic therapy for overactive bladder increases compliance of the neurogenic rectum and alters anorectal reflex activity, with worsening of constipation.

Single-incision laparoscopic-assisted anorectoplasty for treating children with intermediate-type anorectal malformations and rectobulbar fistula: a comparative study.

PURPOSE: Single-incision laparoscopic-assisted anorectoplasty (SILAARP) was compared to posterior sagittal anorectoplasty (PSARP) for treating intermediate-type anorectal malformations (ARMs) with rectobulbar fistula. METHODS: Between December 2011 and January 2016, 48 children with intermediate-type ARMS were treated with SILAARP (n = 34) or PSARP (n = 14) in our centre. Data including demographics, complications, and long-term outcomes were retrospectively compared. RESULTS: No significant difference was observed between both groups in terms of median operative time and complications. The length of postoperative hospital stay was shorter in the SILAARP group than in the PSARP group (6.15 ± 1.10 vs 9.64 ± 4.13 days; p = 0.008). After a mean follow-up of 59.38 ± 13.68 months, the rates of voluntary bowel movements, soiling, and constipation were similar in both groups. Anorectal manometry was performed in 15 and 7 children from the SILAARP and PSARP groups, respectively. Although there were no significant differences in the presence of rectoanal relaxation reflex and high-pressure-zone length, anal canal resting pressure was higher in the SILAARP group than in the PSARP group (33.35 ± 12.95 vs 23.06 ± 8.40 mmHg; p = 0.039). CONCLUSIONS: Both SILAARP and PSARP seemed feasible and effective for treating intermediate-type ARMs with rectobulbar fistula in children. However, SILAARP significantly reduced the length of postoperative hospital stay and improved anal canal resting pressure.

Results of rectoanal manometry after a novel laparoscopic technique: laparoscope-assisted heart-shaped anastomosis for Hirschsprung's disease.

PURPOSE: The present research utilizes a mid-term follow-up study to assess the results of anorectal manometry after laparoscope-assisted heart-shaped anastomosis (LHSA) for Hirschsprung's disease (HSCR), and compares it to a more generally applied approach, the laparoscope-assisted Soave procedure (LSP). METHODS: Retrospectively, patients from January 2015 to June 2017 who received LHSA or LSP were included in this study. After surgery, anorectal manometry was performed by the outpatient department. Anal sphincter resting pressure, anal canal length, amplitude of anal contraction, and frequency of anal contraction pre- and postoperatively were recorded. Additionally, mid-term complications were also monitored. RESULTS: Preoperative manometry showed no statistically significant difference between the LHSA and LSP groups. Postoperatively, anal sphincter resting pressure was lower in the LHSA group (60.64 ± 9.33 vs. 68.84 ± 11.80 mmHg, p = 0.001). Furthermore, anal canal length of the LHSA group was shorter than that of the LSP group (1.41 ± 0.18 vs. 1.53 ± 0.25 cm, p = 0.015). Frequency of anal contraction also showed a statistically significant difference between the LHSA and LSP groups (13.53 ± 2.17 vs. 12.50 ± 2.03 per minute, p = 0.032). The complication rates showed no significant difference and were as follows: incidence of enterocolitis was 13.89% in the LHSA group and 20.45% in the LSP group, incidence of constipation was 11.11% after LHSA and 27.27% after LSP, and incidence of soiling was 13.89% after LHSA and 25.00% after LSP. CONCLUSIONS: Manometric results of this study show satisfactory outcomes after LHSA. LHSA is an advanced surgical technique to make intestinal anastomosis easy and ensure a good prognosis.

Does Bilateral Deep Brain Stimulation of the Subthalamic Nucleus Modify Ano-Rectal Motility in Parkinson's Disease? Results of a Randomized Cross-Over Study.

BACKGROUND: Ano-rectal motility impairment is often observed during Parkinson's disease (PD), generating symptoms as constipation and/or incontinence with impaired quality of life. Subthalamic nuclei (STN) deep brain stimulation (DBS) improves motor symptoms of PD, but its effects on anorectal motility are unknown. This study aimed to assess the effects of STN-DBS on the anorectal motility in PD patients, in a randomized cross-over study. METHODS: Sixteen PD patients with bilateral STN-DBS for at least 6 months were included. The anal resting pressure, duration and maximal amplitude of squeeze effort, recto-anal inhibitory reflex, maximal tolerable rectal volume, and anal pressure during defecation effort were measured and compared after STN-DBS was switched OFF and then ON for 2 hours, or vice-versa, in a randomized order. KEY RESULTS: STN-DBS increased maximal amplitude of anal squeezing pressure (OFF: 85.7 ± 14.5 vs ON: 108.4 ± 21.0 cmH2 O; P = 0.02), with no significant difference in the duration (P = 0.10). No other significant difference was found between stimulation conditions (OFF vs ON) for anal resting pressure (OFF: 72.5 ± 8.6 cmH2 O vs ON: 71.7 ± 9.0 cmH2 O; P = 0.24), recto-anal inhibitory reflex, maximal tolerable rectal volume (OFF: 231 ± 24 mL vs ON: 241 ± 26 mL; P = 0.68), or anal pressure during defecation effort with a similar rate of ano-rectal dyssynergia (7/16 and 8/16 with and without STN-DBS, respectively). No order effect (ON-OFF vs OFF-ON) was observed. CONCLUSION AND INFERENCES: STN-DBS increased anal squeezing pressure, but did not modify anorectal dyssynergia in PD patients, This study demonstrated the involvement of STN in the voluntary control of anorectal motility in PD patients.

Noninvasive neurophysiological mapping of the lower urinary tract in adult and aging rhesus macaques.

The lower urinary tract (LUT) may be activated by spinal cord stimulation, but the physiological mapping characteristics of LUT activation with noninvasive transcutaneous spinal cord stimulation (TSCS) are not known. The effects of aging on the contractile properties of the detrusor are also not well understood. Therefore, TSCS was applied over the T10/T11 to L6/L7 spinous processes in adult ( n = 6) and aged ( n = 9) female rhesus macaques. A combination of urodynamic studies and electromyography recordings of the external urethral sphincter (EUS), external anal sphincter (EAS), and pelvic floor muscles was performed. Distinct functional maps were demonstrated for TSCS-evoked detrusor and urethral pressures and for the activation of the EUS, EAS, and pelvic floor muscles. The magnitude of responses for each peripheral target organ was dependent on TSCS location and strength. The strongest detrusor contraction was observed with TSCS at the L1/L2 site in adults and the L3/L4 site in aged subjects. TSCS-evoked bladder pressure at the L1/L2 site was significantly higher for the adults compared with the aged subjects ( P < 0.05). Cumulative normalized TSCS-evoked pressures, calculated for five consecutive sites between the T11/T12 and L3/L4 levels, were significantly lower for aged compared with adult subjects ( P < 0.05). The aged animals also showed a caudal shift for the TSCS site that generated the strongest detrusor contraction. We conclude that natural aging in rhesus macaques is associated with decreased detrusor contractility, a finding of significant translational research relevance as detrusor underactivity is a common occurrence with aging in humans. NEW & NOTEWORTHY Transcutaneous spinal cord stimulation (TSCS) was used to map lower urinary tract function in adult and aged rhesus macaques. Aging was associated with decreased peak pressure responses to TSCS, reduced cumulative normalized evoked bladder pressure responses, and a caudal shift for the site generating the strongest TSCS-induced detrusor contraction. We demonstrate the utility of TSCS as a new diagnostic tool for detrusor contractility assessments and conclude that aging is associated with decreased detrusor contractility in primates.