Identifying Suspected Volume Conduction Contamination of External Anal Sphincter Motor Evoked Potentials in Lumbosacral Spine Surgery.

PURPOSE: Iatrogenic injury to sacral nerve roots poses significant quality of life issues for patients. Motor evoked potential (MEP) monitoring can be used for intraoperative surveillance of these important structures. We hypothesized that volume conducted depolarizations from gluteus maximus (GM) may contaminate external anal sphincter (EAS) MEP results during lumbosacral spine surgery. METHODS: Motor evoked potential from the EAS and medial GM in 40 patients were prospectively assessed for inter-muscle volume conduction during lumbosacral spine surgeries. Peak latency matching between the EAS and GM MEP recordings conditionally identified volume conduction (VC+) or no volume conduction (VC-). Linear regression and power spectral density analysis of EAS and medial GM MEP amplitudes were performed from VC+ and VC- data pairs to confirm intermuscle electrical cross-talk. RESULTS: Motor evoked potential peak latency matching identified putative VC+ in 9 of 40 patients (22.5%). Mean regression coefficients (r2) from peak-to-peak EAS and medial GM MEP amplitude plots were 0.83 ± 0.04 for VC+ and 0.34 ± 0.06 for VC- MEP (P < 0.001). Power spectral density analysis identified the major frequency component in the MEP responses. The mean frequency difference between VC+ EAS and medial GM MEP responses were 0.4 ± 0.2 Hz compared with 3.5 ± 0.6 Hz for VC- MEP (P < 0.001). CONCLUSIONS: Our data support using peak latency matching between EAS and GM MEP to identify spurious MEP results because of intermuscle volume conduction. Neuromonitorists should be aware of this possible cross-muscle conflict to avoid interpretation errors during lumbosacral procedures using EAS MEP.

TMEM16A in smooth muscle cells acts as a pacemaker channel in the internal anal sphincter.

Maintenance of fecal continence requires a continuous or basal tone of the internal anal sphincter (IAS). Paradoxically, the basal tone results largely from high-frequency rhythmic contractions of the IAS smooth muscle. However, the cellular and molecular mechanisms that initiate these contractions remain elusive. Here we show that the IAS contains multiple pacemakers. These pacemakers spontaneously generate propagating calcium waves that drive rhythmic contractions and establish the basal tone. These waves are myogenic and act independently of nerve, paracrine or autocrine signals. Using cell-specific gene knockout mice, we further found that TMEM16A Cl- channels in smooth muscle cells (but not in the interstitial cells of Cajal) are indispensable for pacemaking, rhythmic contractions, and basal tone. Our results identify TMEM16A in smooth muscle cells as a critical pacemaker channel that enables the IAS to contract rhythmically and continuously. This study provides cellular and molecular insights into fecal continence.

[Chinese expert consensus on clinical diagnosis and treatment of fecal incontinence (2022 edition)].

Fecal incontinence is one of the common diseases in the field of colorectal and anal surgery. Its etiology is complex, the treatment response is suboptimal, and there are controversies in clinical care. There is no consensus on the clinical practice of fecal incontinence in China currently. Launched by Anorectal Branch of Chinese Medical Doctor Association, Expert Committee on Anorectal Disease of Anorectal Branch of Chinese Medical Doctor Association, and Clinical Guidelines Committee of Anorectal Branch of Chinese Medical Doctor Association, and organized by the editorial board of Chinese Journal of Gastrointestinal Surgery, Chinese experts on this field were convened to write the Chinese expert consensus on clinical practice of fecal incontinence based on relevant references. After rounds of discussion, the final consensus combines the latest evidence and experts' clinical experience. This expert group suggested that a comprehensive assessment of fecal incontinence should be conducted before treatment, including medical history, relevant scales, physical examination and special examinations. Special examinations include anorectal endoscopy, anorectal manometry, transrectal ultrasound, magnetic resonance, rectal sensation and compliance, balloon ejection test, pelvic floor electromyography, defecography, colonoscopy and pudendal nerve terminal motor latency. Treatment methods include life style modification, medication, surgery, traditional Chinese medicine and other treatments. This consensus aims to standardize the algorithm of fecal incontinence management and improve therapeutic efficacy.

Kilohertz alternating current neuromodulation of the pudendal nerves: effects on the anal canal and anal sphincter in rats.

The first two objectives were to establish which stimulation parameters of kilohertz frequency alternating current (KHFAC) neuromodulation influence the effectiveness of pudendal nerve block and its safety. The third aim was to determine whether KHFAC neuromodulation of the pudendal nerve can relax the pelvic musculature, including the anal sphincter. Simulation experiments were conducted to establish which parameters can be adjusted to improve the effectiveness and safety of the nerve block. The outcome measures were block threshold (measure of effectiveness) and block threshold charge per phase (measure of safety). In vivo, the pudendal nerves in 11 male and 2 female anesthetized Sprague Dawley rats were stimulated in the range of 10 Hz to 40 kHz, and the effect on anal pressure was measured. The simulations showed that block threshold and block threshold charge per phase depend on waveform, interphase delay, electrode-to-axon distance, interpolar distance, and electrode array orientation. In vivo, the average anal pressure during unilateral KHFAC stimulation was significantly lower than the average peak anal pressure during low-frequency stimulation (p < 0.001). Stimulation with 20 kHz and 40 kHz (square wave, 10 V amplitude, 50% duty cycle, no interphase delay) induced the largest anal pressure decrease during both unilateral and bilateral stimulation. However, no statistically significant differences were detected between the different frequencies. This study showed that waveform, interphase delay and the alignment of the electrode along the nerve affect the effectiveness and safety of KHFAC stimulation. Additionally, we showed that KHFAC neuromodulation of the pudendal nerves with an electrode array effectively reduces anal pressure in rats.

The anorectal defaecation reflex: a prospective intervention study.

AIM: Our hypothesis is that there may be a neural pathway with sensory afferent neurons in the anal canal that leads to rectal contraction to assist defaecation. We aimed to compare rectal motility between healthy participants with or without anal anaesthesia. METHOD: This prospective intervention study consisted of two test sessions: a baseline session followed by an identical second session. During each session we performed the anal electrosensitivity test, the rectoanal inhibitory reflex test and rapid phasic barostat distensions. Prior to the second session, participants were randomly assigned to receive either a local anal anaesthetic or a placebo. RESULTS: We included 23 healthy participants aged 21.1 ± 0.5 years, 13 of whom received an anal anaesthetic and 10 a placebo. All participants showed a transient rectal contraction during the first test session, which decreased significantly after anal anaesthesia (18.6 ml vs. 4.9 ml, p = 0.019). The maximum rectal contraction was comparable to the baseline results in the placebo group. Furthermore, the electrosensitivity at the highest centimetre of the anal canal correlated with the maximum rectal contraction (r = -0.452, p = 0.045). CONCLUSION: All healthy study participants display an involuntary, reproducible rectal reflex contraction that appears to be innervated by afferent nerves in the proximal anal canal. The rectal reflex contraction appears to play a role in defaecation and we therefore refer to this phenomenon as the anorectal defaecation reflex. Knowledge of the anorectal defaecation reflex may have consequences for the diagnostics and treatment of constipation.

Superficial peroneal neuromodulation of nonobstructive urinary retention induced by prolonged pudendal afferent activity in cats.

The purpose of this study is to determine whether superficial peroneal nerve stimulation (SPNS) can improve nonobstructive urinary retention (NOUR) induced by prolonged pudendal nerve stimulation (PNS). In this exploratory acute study using eight cats under anesthesia, PNS and SPNS were applied by nerve cuff electrodes. Skin surface electrodes were also used for SPNS. A double lumen catheter was inserted via the bladder dome for bladder infusion and pressure measurement and to allow voiding without a physical urethral outlet obstruction. The voided and postvoid residual (PVR) volumes were also recorded. NOUR induced by repetitive (4-13 times) application of 30-min PNS significantly (P < 0.05) reduced voiding efficiency by 49.5 ± 16.8% of control (78.3 ± 7.9%), with a large PVR volume at 208.2 ± 82.6% of control bladder capacity. SPNS (1 Hz, 0.2 ms) at 1.5-2 times threshold intensity (T) for inducing posterior thigh muscle contractions was applied either continuously (SPNSc) or intermittently (SPNSi) during cystometrograms to improve the PNS-induced NOUR. SPNSc and SPNSi applied by nerve cuff electrodes significantly (P < 0.05) increased voiding efficiency to 74.5 ± 18.9% and 67.0 ± 15.3%, respectively, and reduced PVR volume to 54.5 ± 39.0% and 88.3 ± 56.0%, respectively. SPNSc and SPNSi applied noninvasively by skin surface electrodes also improved NOUR similar to the stimulation applied by a cuff electrode. This study indicates that abnormal pudendal afferent activity could be a pathophysiological cause for the NOUR occurring in Fowler's syndrome and a noninvasive superficial peroneal neuromodulation therapy might be developed to treat NOUR in patients with Fowler's syndrome.

Translumbosacral Anorectal Magnetic Stimulation Test for Fecal Incontinence.

BACKGROUND: Neuropathy may cause fecal incontinence and mixed fecal incontinence/constipation, but its prevalence is unclear, partly due to the lack of comprehensive testing of spino-anorectal innervation. OBJECTIVE: This study aimed to develop and determine the clinical usefulness of a novel test, translumbosacral anorectal magnetic stimulation for fecal incontinence. DESIGN: This observational cohort study was conducted from 2012 to 2018. SETTINGS: This study was performed at a tertiary referral center. PATIENTS: Patients with fecal incontinence, patients with mixed fecal incontinence/constipation, and healthy controls were included. INTERVENTIONS: A translumbosacral anorectal magnetic stimulation test was performed by using an anorectal probe with 4 ring electrodes and magnetic coil, and by stimulating bilateral lumbar and sacral plexuses, uses and recording 8 motor-evoked potentials at anal and rectal sites. MAIN OUTCOME MEASURES: The prevalence of lumbar and/or sacral neuropathy was examined. Secondary outcomes were correlation of neuropathy with anorectal sensorimotor function(s) and morphological changes. RESULTS: We evaluated 220 patients: 144 with fecal incontinence, 76 with mixed fecal incontinence/constipation, and 31 healthy controls. All 8 lumbar and sacral motor-evoked potential latencies were significantly prolonged (p < 0.01) in fecal incontinence and mixed fecal incontinence/constipation groups compared with controls. Neuropathy was patchy and involved 4.0 (3.0) (median (interquartile range)) sites. Lumbar neuropathy was seen in 29% to 65% of the patients in the fecal incontinence group and 22% to 61% of the patients in the mixed fecal incontinence/constipation group, and sacral neuropathy was seen in 24% to 64% and 29% to 61% of these patients. Anal neuropathy was significantly more (p < 0.001) prevalent than rectal neuropathy in both groups. There was no correlation between motor-evoked potential latencies and anal sphincter pressures, rectal sensation, or anal sphincter defects. LIMITATIONS: No comparative analysis with electromyography was performed. CONCLUSION: Lumbar or sacral plexus neuropathy was detected in 40% to 75% of patients with fecal incontinence with a 2-fold greater prevalence at the anal region than the rectum. Lumbosacral neuropathy appears to be an independent mechanism in the pathogenesis of fecal incontinence, unassociated with other sensorimotor dysfunctions. Translumbosacral anorectal magnetic stimulation has a high yield and is a safe and clinically useful neurophysiological test. See Video Abstract at http://links.lww.com/DCR/B728. PRUEBA DE ESTIMULACIN MAGNTICA TRANSLUMBOSACRAL ANORECTAL PARA LA INCONTINENCIA FECAL: ANTECEDENTES:La neuropatía puede causar incontinencia fecal y una combinación de incontinencia fe-cal/estreñimiento, pero su prevalencia no está clara, en parte debido a la falta de pruebas comple-tas de inervación espino-anorrectal.OBJETIVO:Desarrollar y determinar la utilidad clínica de una nueva prueba, estimulación magnética trans-lumbosacral anorrectal para la incontinencia fecal.DISEÑO:Estudio de cohorte observacional del 2012 al 2018.ENTORNO CLINICO:Centro de referencia terciario.PACIENTES:Pacientes con incontinencia fecal, combinación de incontinencia fecal/estreñimiento y controles sanos.INTERVENCIONES:Se realizó una prueba de estimulación magnética translumbosacral anorrectal utilizando una sonda anorrectal con 4 electrodos anulares y bobina magnética, y estimulando los plexos lumbares y sacros bilaterales y registrando ocho potenciales evocados motores las regiones anal y rectal.PRINCIPALES MEDIDAS DE RESULTADO:Se examinó la prevalencia de neuropatía lumbar y/o sacra. Los resultados secundarios fueron la correlación de la neuropatía con las funciones sensitivomotoras anorrectales y cambios morfológi-cos.RESULTADOS:Evaluamos 220 pacientes, 144 con incontinencia fecal, 76 con combinación de incontinencia fe-cal/estreñimiento y 31 sujetos sanos. Las ocho latencias de los potenciales evocadas motoras lum-bares y sacras se prolongaron significativamente (p <0,01) en la incontinencia fecal y el grupo mixto en comparación con los controles. La neuropatía fue irregular y afectaba 4,0 (3,0) (mediana (rango intercuartílico) sitios. Se observó neuropatía lumbar en 29-65% en la incontinencia fecal y 22-61% en el grupo mixto, y neuropatía sacra en 24-64% y 29-61 % de pacientes respectivamen-te. La neuropatía anal fue significativamente más prevalente (p <0,001) que la rectal en ambos grupos. No hubo correlación entre las latencias de los potenciales evocadas motoras y las presio-nes del esfínter anal, la sensación rectal o los defectos del esfínter anal.LIMITACIONES:Sin análisis comparativo con electromiografía.CONCLUSIÓNES:Se detectó neuropatía del plexo lumbar o sacro en el 40-75% de los pacientes con incontinencia fecal con una prevalencia dos veces mayor en la región anal que en el recto. La neuropatía lumbo-sacra parece ser un mecanismo independiente en la patogenia de la incontinencia fecal, no asocia-do con otras disfunciones sensitivomotoras. La estimulación magnética translumbosacral anorrec-tal tiene un alto rendimiento, es una prueba neurofisiológica segura y clínicamente útil. Consulte Video Resumen en http://links.lww.com/DCR/B728.

Pudendal Nerve Terminal Motor Latency Compared by Anorectal Manometry Diagnosing Fecal Incontinence: A Retrospective Study.

OBJECTIVE: The aim of the study was to compare the clinical value of pudendal nerve terminal motor latency in fecal incontinence patients with that of another diagnostic test-anorectal manometry. DESIGN: This study used a cross-sectional design. Medical records of fecal incontinence patients who underwent pudendal nerve terminal motor latency and anorectal manometry testing were reviewed. Greater than 2.4 ms of pudendal nerve terminal motor latency was determined to be abnormal. Anorectal manometry was performed using a station pull-through technique. Mean resting anal pressure, maximal resting anal pressure, mean squeezing anal pressure, and maximal squeezing anal pressure were investigated. For normal and abnormal pudendal nerve terminal motor latency groups, comparative analyses were performed on anorectal manometry results. RESULTS: A total of 31 patients were included. Thirteen patients showed normal pudendal nerve terminal motor latency. For anorectal manometry results, there was no significant difference between normal and abnormal pudendal nerve terminal motor latency groups. Fourteen patients had diabetes mellitus. Subgroup analysis of the 14 diabetic patients showed no significant difference between normal and abnormal pudendal nerve terminal motor latency groups. For 17 nondiabetic patients, there was a significant difference between the groups with positive correlations with mean/maximal resting anal pressures. CONCLUSIONS: Pudendal nerve terminal motor latency significantly correlates with anorectal manometry in fecal incontinence only in nondiabetic patients.

Chinese expert consensus on clinical diagnosis and treatment of fecal incontinence (2022 edition) / 中华胃肠外科杂志

Fecal incontinence is one of the common diseases in the field of colorectal and anal surgery. Its etiology is complex, the treatment response is suboptimal, and there are controversies in clinical care. There is no consensus on the clinical practice of fecal incontinence in China currently. Launched by Anorectal Branch of Chinese Medical Doctor Association, Expert Committee on Anorectal Disease of Anorectal Branch of Chinese Medical Doctor Association, and Clinical Guidelines Committee of Anorectal Branch of Chinese Medical Doctor Association, and organized by the editorial board of Chinese Journal of Gastrointestinal Surgery, Chinese experts on this field were convened to write the Chinese expert consensus on clinical practice of fecal incontinence based on relevant references. After rounds of discussion, the final consensus combines the latest evidence and experts' clinical experience. This expert group suggested that a comprehensive assessment of fecal incontinence should be conducted before treatment, including medical history, relevant scales, physical examination and special examinations. Special examinations include anorectal endoscopy, anorectal manometry, transrectal ultrasound, magnetic resonance, rectal sensation and compliance, balloon ejection test, pelvic floor electromyography, defecography, colonoscopy and pudendal nerve terminal motor latency. Treatment methods include life style modification, medication, surgery, traditional Chinese medicine and other treatments. This consensus aims to standardize the algorithm of fecal incontinence management and improve therapeutic efficacy.

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.

Anatomical feasibility of peripheral nerve transfer to reestablish external anal sphincter control - cadaveric study.

PURPOSE: Motor deficits affecting anal sphincter control can severely impair quality of life. Peripheral nerve transfer has been proposed as an option to reestablish anal sphincter motor function. We assessed, in human cadavers, the anatomical feasibility of nerve transfer from a motor branch of the tibialis portion of the sciatic nerve to two distinct points on pudendal nerve (PN), through transgluteal access, as a potential approach to reestablish anal sphincter function. METHODS: We dissected 24 formalinized specimens of the gluteal region and posterior proximal third of the thigh. We characterized the motor fascicle (donor nerve) from the sciatic nerve to the long head of the biceps femoris muscle and the PN (recipient nerve), and measured nerve lengths required for direct coaptation from the donor nerve to the recipient in both the gluteal region (proximal) and perineal cavity (distal). RESULTS: We identified three anatomical variations of the donor nerve as well as three distinct branching patterns of the recipient nerve from the piriformis muscle to the pudendal canal region. Donor nerve lengths (proximal and distal) were satisfactory for direct coaptation in all cases. CONCLUSIONS: Transfer of a motor fascicle of the sciatic nerve to the PN is anatomically feasible without nerve grafts. Donor nerve length was sufficient and donor nerve functionally compatible (motor). Anatomical variations in the PN could also be accommodated.

Fecal Incontinence in the Elderly.

Fecal incontinence can be a challenging and stigmatizing disease with a high prevalence in the elderly population. Despite effective treatment options, most patients do not receive care. Clues in the history and physical examination can assist the provider in establishing the diagnosis. Direct inquiry about the presence of incontinence is key. Bowel disturbances are common triggers for symptoms and represent some of the easiest treatment targets. We review the epidemiology and impact of the disease, delineate a diagnostic and treatment approach for primary care physicians to identify patients with suspected fecal incontinence and describe appropriate treatment options.

A Novel High-Density Electromyography Probe for Evaluating Anorectal Neurophysiology: Design, Human Feasibility Study, and Validation with Trans-Sacral Magnetic Stimulation.

Fecal incontinence (FI) substantially impairs quality of life and imparts a major socioeconomic burden. Anal sphincter injury and possibly pudendal nerve damage are considered common causes, however, current clinical methods for evaluating their function remain suboptimal. Electromyography (EMG) and pudendal nerve terminal latencies have been applied with some success, but are not considered standard practice due to uncertain accuracy and clinical value. In this study we developed and applied a novel anorectal high-density (HD) EMG probe in humans and pigs to acquire quantitative electrophysiological metrics of the anorectum. In the human trial we assessed somatic pathways and showed that EMG amplitude was greater for tight voluntary squeezes than light voluntary squeezes (0.03 ± 0.02 mV vs. 0.05 ± 0.03 mV). In a porcine model we applied trans-sacral magnetic stimulation to evoke extrinsically activated involuntary pathways and the resulting motor evoked potentials (MEP) were captured using the HD-EMG probe. The mean MEP amplitude at 50% magnetic stimulation intensity output (MSO) was significantly lower that the MEP amplitude at 85, 95 and 100% MSO (1.52 ± 0.50 mV vs. 3.10 ± 0.60 mV). In conclusion, the use of HD-EMG probe in conjunction with trans-sacral magnetic stimulation, for spatiotemporal mapping of anorectal EMG and MEP activity is anticipated to achieve new insights into FI and could offer improved diagnostic and prognostic biomarkers for anorectal dysfunction.

Translumbosacral Neuromodulation Therapy for Fecal Incontinence: A Randomized Frequency Response Trial.

INTRODUCTION: Treatments for fecal incontinence (FI) remain unsatisfactory because they do not remedy the underlying multifactorial dysfunction(s) including anorectal neuropathy. The aim of this study was to investigate the optimal dose frequency, clinical effects, and safety of a novel treatment, translumbosacral neuromodulation therapy (TNT), aimed at improving neuropathy. METHODS: Patients with FI were randomized to receive 6 sessions of weekly TNT treatments consisting of 600 repetitive magnetic stimulations over each of 2 lumbar and 2 sacral sites with either 1, 5, or 15 Hz frequency. Stool diaries, FI severity indices, anorectal neurophysiology and sensorimotor function, and quality of life were compared. Primary outcome measure was the change in FI episodes/week. Responders were patients with ≥50% decrease in weekly FI episodes. RESULTS: Thirty-three patients with FI participated. FI episodes decreased significantly (∆ ±95% confidence interval, 4.2 ± 2.8 (1 Hz); 2 ± 1.7 (5 Hz); 3.4 ± 2.5 (15 Hz); P < 0.02) in all 3 groups when compared with baseline. The 1 Hz group showed a significantly higher (P = 0.04) responder rate (91 ± 9.1%) when compared with the 5 Hz group (36 ± 18.2%) or 15 Hz (55 ± 18.2%); no difference was found between the 5 and 15 Hz groups (P = 0.667). Anal neuropathy, squeeze pressure, and rectal capacity improved significantly only in the 1 Hz (P < 0.05) group compared with baseline, but not in other groups. Quality of life domains improved significantly (P < 0.05) with 1 and 5 Hz groups. No device-related serious adverse events were noted. DISCUSSION: TNT significantly improves FI symptoms in the short term, and the 1 Hz frequency was overall better than 5 and 15 Hz. Both anorectal neuropathy and physiology significantly improved, demonstrating mechanistic improvement. TNT is a promising, novel, safe, efficacious, and noninvasive treatment for FI (see Visual Abstract, Supplementary Digital Content 3, http://links.lww.com/AJG/B598).

Abnormal Neuronal Response to Rectal and Anal Stimuli in Patients Treated for Distal Rectal Cancer With High-Dose Chemoradiotherapy Followed By Watchful Waiting.

BACKGROUND: Watchful waiting in patients with rectal cancer with complete clinical response after chemoradiation therapy has gained increased popularity to avoid morbidity and mortality associated with surgery. Irradiation of the pelvis causes bowel dysfunction, but the effect on anorectal sensory function remains obscure in this patient category. OBJECTIVE: The aim of this study was to characterize the sensory pathways of the gut-brain axis in patients with rectal cancer treated solely with chemoradiation therapy (nonconventional regime/dose) compared with healthy volunteers. DESIGN: This is an explorative study. SETTINGS: Sensory evaluation by rectal distension was performed and cortical evoked potentials were recorded during rapid balloon distensions of the rectum and anal canal. Latencies and amplitudes of cortical evoked potentials were compared, and the relative amplitude of 5 spectral bands from recorded cortical evoked potentials was used as an additional proxy of neuronal processing. PATIENTS: Patients with rectal cancer solely with chemoradiation therapy (n = 13) a median of 3.2 years ago (range, 2.3-5.6 y) and healthy volunteers (n = 13) were included. MAIN OUTCOME MEASURES: Cortical evoked potentials were measured. RESULTS: Patients had 35% lower rectal capacity at a maximum tolerable volume (p = 0.007). We found no differences in rectal cortical evoked potential latencies (p = 0.09) and amplitudes (p = 0.38) between groups. However, spectral analysis of rectal cortical evoked potentials showed a decrease in θ (4-8 Hz) and an increase in ß (12-32 Hz) band activity in patients (all p < 0.001). Anal cortical potentials showed an increase in α (8-12 Hz) and ß and a decrease in γ (32-70 Hz) band activity (all p < 0.001) in patients compared with healthy volunteers. LIMITATIONS: This is an explorative study of limited size. CONCLUSIONS: Chemoradiation therapy for distal rectal cancer causes abnormal cortical processing of both anal and rectal sensory input. Such central changes may play a role in symptomatic patients, especially when refractory to local treatments. See Video Abstract at http://links.lww.com/DCR/B270. RESPUESTA NEURONAL ANORMAL A ESTÍMULOS RECTALES Y ANALES, EN PACIENTES TRATADOS POR CÁNCER RECTAL DISTAL, CON QUIMIORRADIOTERAPIA DE DOSIS ALTA, SEGUIDA DE ESPERA VIGILANTE: La espera vigilante en pacientes de cáncer rectal, con respuesta clínica completa después de la quimiorradiación, ha ganado una mayor popularidad en evitar la morbilidad y mortalidad asociadas con la cirugía. La irradiación de la pelvis causa disfunción intestinal, pero el efecto sobre la función sensorial ano-rectal sigue siendo no claro, en esta categoría de pacientes.El objetivo de este estudio, fue caracterizar las vías sensoriales del eje intestino-cerebro en pacientes con cáncer rectal, tratados únicamente con quimiorradiación (régimen / dosis no convencional), en comparación con voluntarios sanos.Es un estudio exploratorio.Se realizó una evaluación sensorial por distensión rectal y se registraron los potenciales evocados corticales, durante las distensiones rápidas con balón en recto y canal anal. Se compararon las latencias y amplitudes de los potenciales evocados corticales, y la amplitud relativa de cinco bandas espectrales registradas, de potenciales evocados corticales, se usaron como proxy adicional del procesamiento neuronal.Pacientes de cáncer rectal, únicamente con terapia de quimiorradiación (n = 13) mediana de 3.2 años (rango 2.3-5.6) y voluntarios sanos (n = 13).Potenciales evocados corticales.Pacientes tuvieron una capacidad rectal menor del 35%, al volumen máximo tolerable (p = 0.007). No encontramos diferencias en las latencias potenciales evocadas corticales rectales (p = 0.09) y amplitudes (p = 0.38) entre los grupos. Sin embargo, el análisis espectral de los potenciales evocados corticales rectales, mostró una disminución en theta (4-8 Hz) aumento en beta (12-32 Hz), y actividad en banda en pacientes (todos p <0.001). Los potenciales evocados corticales anales mostraron un aumento en alfa (8-12 Hz) y beta, disminución en gamma (32-70 Hz), y actividad en banda (todos p <0.001), en pacientes comparados a voluntarios sanos.Este es un estudio exploratorio de tamaño limitado.La quimiorradiación para el cáncer rectal distal, ocasiona procesos corticales sensoriales anormales anales y rectales. Tales cambios centrales pueden desempeñar un papel en pacientes sintomáticos, especialmente cuando son refractarios a tratamientos locales. Consulte Video Resumen en http://links.lww.com/DCR/B270.

A novel intramuscular Interstitial Cell of Cajal is a candidate for generating pacemaker activity in the mouse internal anal sphincter.

The internal anal sphincter (IAS) generates phasic contractions and tone. Slow waves (SWs) produced by interstitial cells of Cajal (ICC) underlie phasic contractions in other gastrointestinal regions. SWs are also present in the IAS where only intramuscular ICC (ICC-IM) are found, however the evidence linking ICC-IM to SWs is limited. This study examined the possible relationship between ICC-IM and SWs by recording Ca2+ transients in mice expressing a genetically-encoded Ca2+-indicator in ICC (Kit-Cre-GCaMP6f). A role for L-type Ca2+ channels (CavL) and anoctamin 1 (ANO1) was tested since each is essential for SW and tone generation. Two distinct ICC-IM populations were identified. Type I cells (36% of total) displayed localised asynchronous Ca2+ transients not dependent on CavL or ANO1; properties typical of ICC-IM mediating neural responses in other gastrointestinal regions. A second novel sub-type, i.e., Type II cells (64% of total) generated rhythmic, global Ca2+ transients at the SW frequency that were synchronised with neighbouring Type II cells and were abolished following blockade of either CavL or ANO1. Thus, the spatiotemporal characteristics of Type II cells and their dependence upon CavL and ANO1 all suggest that these cells are viable candidates for the generation of SWs and tone in the IAS.

[Surgical key points of precision functional sphincter-preserving surgery].

The principle of sphincter-preserving surgery is to preserve the anal sphincter function under the premise of radical resection. Due to low position of rectal tumor, conventional laparoscopic surgery has difficulties in operating in the deep and narrow pelvis, which may lead to inaccurate tissue dissociation, imprecise positioning of tumor edge, excessive stretch of the anal sphincter complex, and excessive removal of distal rectal mucosa. Moreover, pain from abdominal auxiliary incision has an unavoidable side effect for postoperative recovery. With the help of the Liu's transanal microsurgery system, precision functional sphincter-preserving surgery (PPS) can be successfully performed. PPS tries to preserve left colonic artery and pelvic autonomic nerve in the transabdominal operation. In the part of transanal surgery, measurement, localization and resection of the lower edge of the tumor are conducted under a clear and open visual field with the transparent screw anal dilator. After the rectum is cut off, the specimen is taken out through the anus to avoid abdominal incision. Inserting the intestinal supporter to support the bowel stump, full thickness of bowel stump is then sutured with anal canal by vertical mattress suture. Special transanal tube is placed afterwards without routine prophylactic stoma. PPS can achieve precise tumor resection and sphincter preservation simultaneously.

[Tarlov cyst and faecal incontinence: A case report and literature review]. / Quiste de Tarlov e incontinencia fecal: caso clínico y revisión de la literatura.

Tarlov, or perineural cysts, are lesions of the nerve root usually located at the sacral level of the spine. Their cause is unclear. These cysts are generally identified as an incidental finding and are usually asymptomatic. Symptomatic cysts are infrequent, with symptoms usually consisting of pain, radiculopathy and, less frequently, bladder, bowel and sexual dysfunction. We report the case of a 70-year-old woman with Tarlov cyst, provoking faecal incontinence, and review the aetiology, pathophysiology and management of this particular case.