Rectal Distension Research Articles

Characterization of Simultaneous Pressure Waves as Biomarkers for Colonic Motility Assessed by High-Resolution Colonic Manometry.

Simultaneous pressure waves (SPWs) in manometry recordings of the human colon have been associated with gas expulsion. Our hypothesis was that the SPW might be a critical component of most colonic motor functions, and hence might act as a biomarker for healthy colon motility. To that end, we performed high-resolution colonic manometry (HRCM), for the first time using an 84-sensor (1 cm spaced) water-perfused catheter, in 17 healthy volunteers. Intraluminal pressure patterns were recorded during baseline, proximal and rectal balloon distention, after a meal and following proximal and rectal luminal bisacodyl administration. Quantification was performed using software, based on Image J, developed during this study. Gas expulsion was always associated with SPWs, furthermore, SPWs were associated with water or balloon expulsion. SPWs were prominently emerging at the termination of proximal high amplitude propagating pressure waves (HAPWs); we termed this motor pattern HAPW-SPWs; hence, SPWs were often not a pan-colonic event. SPWs and HAPW-SPWs were observed at baseline with SPW amplitudes of 12.0 ± 8.5 mmHg and 20.2 ± 7.2 mmHg respectively. The SPW occurrence and amplitude significantly increased in response to meal, balloon distention and luminal bisacodyl, associated with 50.3% anal sphincter relaxation at baseline, which significantly increased to 59.0% after a meal, and 69.1% after bisacodyl. Often, full relaxation was achieved. The SPWs associated with gas expulsion had a significantly higher amplitude compared to SPWs without gas expulsion. SPWs could be seen to consist of clusters of high frequency pressure waves, likely associated with a cluster of fast propagating, circular muscle contractions. SPWs were occasionally observed in a highly rhythmic pattern at 1.8 ± 1.2 cycles/min. Unlike HAPWs, the SPWs did not obliterate haustral boundaries thereby explaining how gas can be expelled while solid content can remain restrained by the haustral boundaries. In conclusion, the SPW may become a biomarker for normal gas transit, the gastrocolonic reflex and extrinsic neural reflexes. The SPW assessment reveals coordination of activities in the colon, rectum and anal sphincters. SPWs may become of diagnostic value in patients with colonic dysmotility.

Behavioural and neural responses to aversive visceral stimuli in women with primary dysmenorrhoea.

BackgroundChronic pelvic pain, in particular dysmenorrhoea, is a significant yet unresolved healthcare problem in gynaecology. As interoceptive sensitivity and underlying neural mechanisms remain incompletely understood, this functional magnetic resonance imaging (fMRI) study assessed behavioural and neural responses to visceral stimuli in primary dysmenorrhoea (PMD).MethodsWomen with PMD (N = 19) without psychological comorbidity and healthy women (N = 20) were compared with respect to visceral sensory and pain thresholds, and to neural responses to individually calibrated mildly painful and painful rectal distensions implemented during scanning. Trial‐by‐trial ratings of perceived intensity were accomplished with visual analogue scales (VAS).ResultsAlthough women with dysmenorrhoea reported significantly higher chronic pain intensity and pain interference with daily life activities (p < 0.01, assessed with the West Haven‐Yale Multidimensional Pain Inventory), there were no differences between groups in visceral sensitivity and mean trial‐by‐trial VAS ratings were virtually identical. Analysis of neural responses revealed activation in brain regions previously shown to be involved in the processing of visceral stimuli with differences between painful and mildly painful stimulation, but no group differences were found even when using a liberal statistical threshold.ConclusionsDysmenorrhoea patients show unaltered perceptual and neural responses to experimental interoceptive stimuli. Despite limited sample size, these negative results argue against a generalized sensitization towards interoceptive stimuli in patients without psychological comorbidities. Future studies should clarify the role of psychosocial factors in central sensitization using more pain region‐specific models in larger and clinically more heterogeneous samples.SignificanceDespite higher chronic pain and pain interference with daily life activities, women with primary dysmenorrhoea do not differ from healthy women with respect to visceral sensitivity or neural processing of aversive interoceptive stimuli induced by rectal distensions. Generalized sensitization may be present only in subgroups with pronounced psychosocial or psychiatric disturbances.

The Protective Effect of Melissa officinalis L. in Visceral Hypersensitivity in Rat Using 2 Models of Acid-induced Colitis and Stress-induced Irritable Bowel Syndrome: A Possible Role of Nitric Oxide Pathway.

Background/AimsThe aim of present study is to estimate the effects of Melissa officinalis L. (MO) on visceral hypersensitivity (VH), defecation pattern and biochemical factors in 2 experimental models of irritable bowel syndrome (IBS) and the possible role of nitric oxide.MethodsTwo individual models of IBS were induced in male Wistar-albino rats. In the acetic acid model, the animals were exposed to rectal distension and abdominal withdrawal reflex, and the defecation patterns were determined. In the restraint stress model, the levels of TNF-α, myeloperoxidase, lipid peroxidation, and antioxidant powers were determined in the (removed) colon. Rats had been treated with MO, L-NG-nitroarginine methyl ester (L-NAME), aminoguanidine (AG), MO + AG, or MO + L-NAME in the mentioned experimental models.ResultsHypersensitive response to rectal distension and more stool defecation in control rats have been observed in comparison to shams. MO-300 significantly reduced VH and defecation frequency in comparison to controls. VH and defecation pattern did not show significant change in AG + MO and L-NAME + MO groups compared to controls. Also, significant reduction in TNF-α, myeloperoxidase, thiobarbituric acid reactive substances (TBARS), and an increase in antioxidant power in MO-300 group was recorded compared to controls. AG + MO and L-NAME + MO groups showed a reverse pattern compared to MO-300 group.ConclusionsMO can ameliorate IBS by modulating VH and defecation patterns. Antioxidant and anti-inflammatory properties along with its effect on the nitrergic pathway seem to play important roles in its pharmacological activity.

A pharmacological challenge predicts reversible rectal sensorimotor dysfunctions in women with fecal incontinence.

In order to understand the pathophysiology of rectal sensorimotor dysfunctions in women with fecal incontinence (FI) and rectal urgency, we evaluated the effects of a muscarinic antagonist and an adrenergic α2 agonist on these parameters. Firstly, rectal distensibility and sensation were evaluated with a barostat and sinusoidal oscillation at baseline and after randomization to intravenous saline or atropine in 16 healthy controls and 44 FI patients. Thereafter, FI patients were randomized to placebo or clonidine for 4wk; rectal compliance and sensation were revaluated thereafter. The effect of atropine and clonidine on rectal functions and the relationship between them were evaluated. At baseline, compared to controls, rectal capacity was lower (P=.03) while the mean pressure (P=.02) and elastance (P=.01) during sinusoidal oscillation were greater, signifying reduced distensibility, in FI. Compared to placebo, atropine increased (P≤.02) the heart rate in controls and FI and reduced (P=.03) the variability in rectal pressures during sinusoidal oscillation in controls. Clonidine increased rectal compliance (P=.04) and reduced rectal capacity (P=.03) in FI. The effects of atropine and clonidine on compliance (r=.44, P=.003), capacity (r=.34, P=.02), pressures during sinusoidal oscillation (r=.3, P=.057), pressure (r=.6, P<.0001), and volume sensory thresholds (r=.48, P=.003) were correlated. The effects of atropine and clonidine on rectal distensibility and sensation were significantly correlated. A preserved response to atropine suggests that reduced rectal distensibility is partly reversible, mediated by cholinergic mechanisms, and may predict the response to clonidine, providing a pharmacological challenge.

Electroacupuncture via chronically implanted electrodes improves gastric dysmotility mediated by autonomic-cholinergic mechanisms in a rodent model of functional dyspepsia.

Electroacupuncture (EA) has been shown to be effective in reducing symptoms in patients with functional dyspepsia (FD). However, its mechanisms remain largely unknown. The aim of this study was to investigate mechanisms of the prokinetic effects of EA in a rodent model of FD. A FD model was established by neonatal treatment of iodoacetamide (IA). Eight weeks later, the rats were implanted with electrodes in the stomach for the measurement of gastric slow waves (GSW) and electrodes into acupoints ST36 for EA. Autonomic functions were assessed by the spectral analysis of heart rate variability. (i) The IA-treated rats ("FD" rats) showed increased dysrhythmia in both fasting and fed states (P<.01) as well as during rectal distention (P<.02). EA reduced the percentage of dysrhythmia (P<.05 for both fasting and fed) and normalized RD-induced impairment in GSW in "FD" rats. Atropine blocked the effect of EA on GSW. (ii) "FD" rats showed delayed gastric emptying (P=.001 vs control) that was accelerated with EA (P=.01, vs sham-EA). (iii) "FD" rats showed increased plasma norepinephrine (P=.006, vs control) that was suppressed with EA (P=.003) and reduced vagal activity that was improved with EA. Gastric motility (GSW and GE) is impaired in rats treated with IA, possibly attributed to impaired autonomic functions. EA improves GSW and accelerates GE mediated via the autonomic and cholinergic mechanisms.

Su1634 - Ameliorating Effect and Mechanism of Vagal Nerve Stimulation on Gastric Slow Wave Dysrhythmia Induced by Rectal Distension

Su1634 - Ameliorating Effect and Mechanism of Vagal Nerve Stimulation on Gastric Slow Wave Dysrhythmia Induced by Rectal Distension

Anal and rectal function after intensity-modulated prostate radiotherapy with endorectal balloon

Background and purposeLate anorectal toxicity influences quality of life after external beam radiotherapy (EBRT) for prostate cancer. A daily inserted endorectal balloon (ERB) during EBRT aims to reduce anorectal toxicity. Our goal is to objectify anorectal function over time after prostate intensity-modulated radiotherapy (IMRT) with ERB. Material and methodsSixty men, irradiated with IMRT and an ERB, underwent barostat measurements and anorectal manometry prior to EBRT and 6 months, one year and 2 years after radiotherapy. Primary outcome measures were rectal distensibility and rectal sensibility in response to stepwise isobaric distensions and anal pressures. ResultsForty-eight men completed all measurements. EBRT reduced maximal rectal capacity 2 years after EBRT (250 ± 10 mL vs. 211 ± 10 mL; p < 0.001), area under the pressure–volume curve (2878 ± 270 mL mmHg vs. 2521 ± 305 mL mmHg; p = 0.043) and rectal compliance (NS). Sensory pressure thresholds for first sense and first urge (both p < 0.01) increased. Anal maximum pressure diminished after IMRT (p = 0.006). ConclusionsRectal capacity and sensory function are increasingly affected over time after radiotherapy. There is an indication that these reductions are affected less with IMRT + ERB compared to conventional radiation techniques.

Abnormal neuronal response to rectal and anal stimuli in patients treated with primary radiotherapy for anal cancer

IntroductionSphincter-sparing radiotherapy or chemoradiation (RT/CRT) have become the standard treatments for most patients with anal cancer. Unfortunately, long-term survivors often suffer from severe bowel symptoms indicating sensory dysfunction. The aim of the present study was to characterize the sensory pathways of the brain–gut axis after radiotherapy for anal cancer. MethodCortical evoked potentials (CEPs) were recorded during repeated, rapid balloon distensions of the rectum and anal canal in 13 patients with anal cancer treated with radiotherapy or chemoradiation and in 17 healthy volunteers. Latencies and amplitudes of rectal CEPs were compared between the groups. CEPs from both rectal and anal distensions were examined using single sweep spectral band analysis to determine the relative amplitude of five spectral bands as a proxy of neuronal processing. ResultsGroups were comparable by age (62.4 ± 7.8 vs 58.9 ± 8.9, p < 0.32) and gender. Patients had a mean Wexner fecal incontinence score of 5.5 (±3.8) and median LARS Score of 29 (0–39). Rectal CEP latencies were prolonged in patients (F = 11.7; p < 0.001), whereas amplitudes were similar (F = 0.003; p = 0.96). Spectral analysis of CEPs from rectal distensions showed significant differences between groups in theta (4–8 Hz), alpha (8–12 Hz), beta (12–32 Hz) and gamma (32–70 Hz) bands (all p < 0.001) and CEPs from anal distensions showed significant differences in the alpha, beta and gamma bands (all p ≤ 0.002). ConclusionPatients treated with RT/CRT for anal cancer have impaired ano-rectal sensory pathways and abnormal cortical processing. This may play a central role for the pathogenesis of late proctopathy.

Correction: MicroRNA-29a increased the intestinal membrane permeability of colonic epithelial cells in irritable bowel syndrome rats.

[This corrects the article DOI: 10.18632/oncotarget.20687.].

Impact of rectal distension on prostate CBCT-based positioning assessed with 6 degrees-of-freedom couch

IntroductionProstate requires a daily correction of its 3-dimensional position in relation with rectal distension. In this study, we sought to determine whether rectal distension with respect to the rectal behavior might have an impact on prostate translations and/or rotations during prostate image guided radiation therapy using a 6 degrees-of-freedom (DOF) couch. Methods and materialsWe reviewed the data from 39 patients with localized prostate cancer treated with protracted external radiation therapy using a 6 DOF couch. Before each fraction, a kilovoltage cone beam computed tomography (kV-CBCT) scan was performed. The automatic fusion algorithm was set to fuse on soft tissue and allowed correction for translations in 3 dimensions and rotations in the longitudinal axis (“roll”) and lateral axis (“pitch”). After contouring the rectum on each kV-CBCT, we determined the cross-sectional area (CSA) and relative CSA (CSArel) by dividing with the CSA of planning CT. The standard deviation of CSArel per patient was used to classify the patients in 2 groups: patients with a stable rectum and patients with an unstable rectum. The CSArel was compared between these 2 groups with a linear mixed model with group as fixed effect and patient as random effect. ResultsA total of 616 kV-CBCT were analyzed, and 2 subgroups of patients could be defined a posteriori: 19 patients had a stable rectum, mean CSArel (1.06 ± 0.08); the other 20 patients had an unstable rectum, mean CSArel (1.43 ± 0.08). The average pitch in the group with a stable rectum was 0.36° (±0.21) versus 0.40° (±0.20) (P = .898). The pitch was not correlated with the CSArel (P = -.065, r = 0.119). The average roll in the group with a stable rectum was 0.27° (±0.16) versus 0.05° (±0.16) (P = .137). The roll was not correlated with the CSA (P = .094, r = 0.068). The average CSArel was higher (P = .0013) and more variable (P = .035) in the unstable group. ConclusionRectal distension had no impact on the pitch or on the roll, which suggest that a 6 DOF couch has little interest in daily practice for prostate image guided radiation therapy.

Time-dependent dose distribution changes in prostate brachytherapy with iodine seeds.

115 Background: Prostate brachytherapy with iodine seeds has a lasting dose delivery due to a long half life of I125 (i.e. 2 months). To assess changes in dose metrics over time in low-dose rate prostate brachytherapy with iodine seeds and its relationship with rectal distension. Methods: One hundred and twenty-one post-implant CT scans performed every 2 weeks over 2 months after the treatment procedure were analyzed for dosimetry. Each CT-scan was performed without and with rectal enema. The following rectal parameters were collected to evaluate the influence of rectal distension over time: rectal volume, cross-sectional surface area (CSA) and relative CSA calculated from the first CT-scan chosen as reference (CTref). Results: Mean V150% and V200% of the prostate volume increased significantly over time (p &lt; 0.0001) and were significantly higher on postimplant CT scan performed at day 45 (CT45) (p = 0.024 and p = 0.003, respectively) and CT scan performed at day 60 (CT60) (p = 0.0005 and p &lt; 0.0001, respectively) compared with CTref. All dosimetric parameters for the rectum were significantly increased over time. No rectal parameters were significantly different after rectal enema and there was no difference in doses delivered to the prostate and the rectum after rectal emptying. Conclusions: Increased hot spots in the prostate and the rectum during the 2 months following the procedure with iodine seeds may be related to prostate shrinkage rather than rectal distension. We hypothesize that radioelements with shorter half-life (Pd103 or Cs131) or HDR may give less toxicity, as dose distribution is less time-dependent.

The impact of naloxegol on anal sphincter function - Using a human experimental model of opioid-induced bowel dysfunction

Background and aimsOpioid treatment interferes with anal sphincter function and its regulation during defecation. This may result in straining, incomplete evacuation, and contribute to opioid-induced bowel dysfunction (OIBD). Employing an experimental model of oxycodone-induced OIBD, we hypothesized that co-administration of the peripherally acting μ-opioid antagonist naloxegol would improve anal sphincter function in comparison to placebo. MethodsIn a double-blind randomized crossover trial, 24 healthy males were assigned to a six-day treatment of oral oxycodone 15 mg twice daily in combination with either oral naloxegol 25 mg once daily or placebo. At baseline and at day 6, anal resting pressure and the recto-anal inhibitory reflex (RAIR) were evaluated using manometry and rectal balloon distension. Furthermore, the functional lumen imaging probe was used to measure distensibility of the anal canal. Gastrointestinal symptoms were assessed with the Patient Assessment of Constipation Symptom (PAC-SYM) questionnaire and the Bristol Stool Form Scale. ResultsDuring oxycodone treatment, naloxegol improved RAIR-induced sphincter relaxation by 15% (−45.9 vs −38.8 mm Hg; P < 0.01). No differences in anal resting pressure and anal canal distensibility were found between treatments (all P > 0.5). Naloxegol improved PAC-SYM symptoms (mean score over days; 2.6 vs 4.5, P < 0.001) and improved stool consistency scores (mean score over days; 3.3 vs 2.9, P < 0.01). ConclusionsIn this experimental model of OIBD, naloxegol improved the RAIR and reduced gastrointestinal symptoms. Hence, in contrast to conventional laxatives, naloxegol may regulate opioid-induced anal sphincter dysfunction and facilitate the defecation process.

Are characteristics of abdominal pain helpful to identify patients with visceral hypersensitivity in irritable bowel syndrome? Results of a prospective study.

Some consider that patients with visceral hypersensitivity may represent a separate entity within the IBS population not only from a pathophysiological but also from a clinical perspective. The aim of this prospective exploratory study was to assess whether characteristics of abdominal pain in IBS patients could be suggestive of hypersensitivity. This prospective study included consecutive IBS patients selected by Rome III criteria. Validated scores (IBS-SSS, Bristol stool scale, HADS) were used to phenotype patients who were also asked to describe the main location of their abdominal pain on a simple image (abdomen divided into 6 zones). Progressive isobaric rectal distensions were performed to demonstrate, with the ascending method of limits, allodynia (pain threshold lower than 24mmHg). Fifty patients (women: 72%), 42.6±15.7years old, were included. Sub-types were IBS-D, IBS-C and IBS-M in 58%, 22% and 20% of cases, respectively. Allodynia was present in 18% of cases. Neither IBS-SSS nor intensity of pain was predictive of hypersensitivity. In hypersensitive patients, pain was more often located in one of the two iliac fossa (P=0.02) and located outside these areas in only 11% of cases. The sensitivity and the specificity of this pain location to differentiate hyper from normosensitive patients were 0.89 and 0.59, respectively. The location of pain is different between hyper and normosensitive IBS patients. Pain located outside one of the two iliac fossa suggests that the patient is normosensitive.

High-resolution anorectal manometry in children with functional constipation: a single-centre experience before and after treatment.

IntroductionConstipation is a common disorder among children, and most of the cases are functional in aetiology. Few studies have reported the manometric data of normal and constipated children.AimTo evaluate the manometric parameters in children with functional constipation and to assess any possible changes in these parameters after treatment.Material and methodsA prospective descriptive study was conducted at a single centre, enrolling 50 children diagnosed with functional constipation based on Rome IV criteria. Their age ranged from 6 to 14 years with a mean of 7.31 ±1.72 years. High-resolution manometry was performed on all children at the initial presentation and after six months of treatment.ResultsThe studied children showed markedly abnormal rectal sensation parameters (increased first sensation, first urge, intense urge, and maximum tolerable volume) during rectal balloon distension. These parameters were even higher in children with stool incontinence (p = 0.005). Manometric data after 6 months of treatment showed that the resting and squeeze pressures were increased when compared to pre-treatment recordings; however, both were statistically insignificant (p = 0.474 and p = 0.155, respectively). Abnormalities in rectal sensations and the manometric parameters reached near normal values following treatment.ConclusionsAnorectal manometry is sensitive in predicting improvement in patient condition even before complete clinical cure, and it has a prognostic role in the management of childhood constipation. More research is still needed before recommending anorectal manometry as a routine diagnostic or prognostic tool in paediatric constipation management.

Some Autonomic Deficits of Acute or Chronic Cervical Spinal Contusion Reversed by Interim Brainstem Stimulation.

Prolonged electrical stimulation of the hindbrain's nucleus raphe magnus (NRM) or of its major midbrain input region, the periaqueductal gray (PAG), was previously found in rats to promote recovery from sensory-motor and histological deficits of acute thoracic spinal cord injury (SCI). Here, some visceral deficits of acute and chronic midline cervical (C5) contusion are similarly examined. Cranially implanted wireless stimulators delivered intermittent 8 Hz, 30-70 μA cathodal pulse trains to a brainstem microelectrode. Injured controls were given inactive stimulators; rats without injuries or implants were also compared. Rectal distension or squeezing of the forepaws caused an exaggerated rise in mean arterial pressure in injured, untreated rats under anesthesia on post-injury week 6, probably reflecting autonomic dysreflexia (AD). These pressor responses became normal when 7 days of unilateral PAG stimulation was started on the injury day. Older untreated injuries (weeks 18-19) showed normal pressor responses, but unexpectedly had significant resting and nociceptive bradycardia, which was reversed by 3 weeks of PAG stimulation started on weeks 7 or 12. Subsequent chronic studies examined gastric emptying (GE), as indicated by intestinal transit of gavaged dye, and serum chemistry. GE and fasting serum insulin were reduced on injury weeks 14-15, and were both normalized by ∼5 weeks of PAG stimulation begun in weeks 7-8. Increases in calcitonin gene-related peptide, a prominent visceral afferent neurotransmitter, measured near untreated injuries (first thoracic segment) in superficial dorsal laminae were reversed by acutely or chronically initiated PAG stimulation. The NRM, given 2-3 weeks of stimulation beginning 2 days after SCI, prevented abnormalities in both pressor responses and GE on post-injury week 9, consistent with its relaying of repair commands from the PAG. The descending PAG-NRM axis thus exhibits broadly restorative influences on visceral as well as sensory-motor deficits, improving chronic as well as acute signs of injury.

Magnetic resonance imaging analysis of brain function in patients with irritable bowel syndrome

BackgroundIrritable bowel syndrome (IBS) is a common functional disease of the gastrointestinal tract. The current study aimed to examine the association between visceral hypersensitivity in IBS and cortical activation using functional magnetic resonance imaging (fMRI), and to elucidate the role of psychological factors in the pathogenesis of IBS.MethodsThe present study included 31 patients with IBS and 20 healthy controls. Cerebral function was assessed using fMRI. During imaging, a Sengstaken-Blakemore tube was placed within the rectum approximately 10 cm from the anus, following which gas was rapidly injected into the airbag using a 150-ml syringe. Images were obtained at 40 ml, 80 ml, and 120 ml of expansion. Psychological status was evaluated using the Hospital Anxiety and Depression Scale (HADS).ResultsAnxiety and depression scores were higher among patients with IBSthan among controls (both P < 0.05), although scores in both groups were below the level of clinical diagnosis. Brain activation in regions of interest (parietal areas, prefrontal cortex, cerebellum, anterior cingulate cortex, insular cortex, and thalamus) increased along with increases in rectal balloon dilation, except in women with IBS and patients with disease duration less than 5 years. Furthermore, region of interest (ROI) activation (such as the parietal region, prefrontal cortex, cerebellum, anterior cingulate cortex, insular cortex, and thalamus) differed significantly between the 40-ml and 120-ml conditions, and between the 80-ml and 120-ml conditions (P < 0.05), among patients with IBS with anxiety or depression scores less than 9 points.ConclusionsOverall, our findings indicate that changes in brain activation due to changes in rectal balloon distension can be objectively and accurately measured using fMRI. Although our results indicated that visceral hypersensitivity during IBS is associated with changes in cortical activation, further studies utilizing larger sample sizes are required to more fully elucidate the association between psychological factors and visceral hypersensitivity in IBS.

Benefits & pitfalls of administration of rectal gel enema in MRI assessment of rectal cancer

ObjectivesTo assess diagnostic benefits of filling of the rectum with ultrasound gel during MR assessment of rectal cancer and the pitfalls that occurs due to rectal distention. Materials/methods40 patients presented with rectal cancer for either initial MR staging or for assessment after neoadjuvent chemoradiotherapy using ultrasound transmission gel as a contrast for rectal filling. ResultsMR with gel rectal filling showed better depiction in all patients with small tumors than in non filling of the rectum. The filling of rectum with gel increased the distance of the lower tumor border from the anal verge however it showed better assessment of the site of the fixed tumor lower edge in all cases of pedunculated tumor masses. Also rectal filling decreases the distance from the perirectal fascia which may affect the CRM. ConclusionsMR with rectal gel filling is useful in assessment of cases with rectal cancer and by combining empty rectum & distended rectum in the same study we can get the benefits & avoid the pitfalls by correlating the images in both techniques.Clinical Relevance/Application This study helped in assessment of patients with rectal cancer either referred for initial MR staging or for assessment after neoadjuvent chemoradiotherapy.

To prep or not to prep - that is the question: A randomized trial on the use of antiflatulent medication as part of bowel preparation for patients having image guided external beam radiation therapy to the prostate

IntroductionRadiation therapy is a standard treatment option for prostate cancer. With growing use of escalated doses and tighter margins, procedures to limit rectal size variation are needed to reduce prostate motion, increase treatment accuracy, and minimize rectal toxicity. This prospective study was done to determine whether the introduction of an antiflatulent medication would decrease rectal distention at computed tomography (CT) simulation and throughout a course of radiation therapy. Methods and materialsPatients undergoing a radical course of radiation therapy to the prostate/prostate bed were eligible to participate. Participants were randomly assigned to the intervention arm (antiflatulent medication) or the control arm (no medication). For each participant, the number of CT simulation rescans was recorded. Rectal diameters were measured on CT simulation and treatment cone beam CT scans. Acute rectal toxicities were assessed at baseline and weekly using National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), version 4.0. A χ2 analysis was used to compare the number of participants requiring a rescan in each study arm. Change in rectal diameter over time was assessed using repeated measures analysis of variance. ResultsA total of 78 patients participated, with equal numbers assigned to each study arm. There was no significant difference between arms in the number of participants requiring a CT simulation rescan (P = .5551). There was no significant variation in rectal diameter between arms (P = .8999); however, there was a significant effect of time (P = .0017) and a significant interaction effect between study arm and time on rectal diameter (P = .0141). No acute rectal toxicities above grade 2 were reported. ConclusionsThe addition of antiflatulent medication did not affect the frequency of CT simulation rescans. Both time and the interaction between study arm and time had a statistically significant effect on rectal diameter, although neither finding was clinically significant. Instead, standardized bowel preparation education developed for this study may have been sufficient to limit rectal size variation.

Influence of Uncertain Anticipation on Brain Responses to Aversive Rectal Distension in Patients With Irritable Bowel Syndrome.

We investigated whether certainty and uncertainty of impending aversive visceral sensation differently modulate regional brain activity, both during anticipation and visceral sensation in irritable bowel syndrome (IBS) patients compared with healthy controls. Twenty-six IBS patients (14 women) and 29 healthy controls (15 women) were enrolled in a functional magnetic resonance imaging study. Participants received rectal distention at an individually titrated severe discomfort level that was preceded by visual cues to induce certain (100% chance of distention), uncertain (50% chance), and safe (0% chance) anticipation. Subjective ratings of anticipatory fear before and discomfort during distention were similar between IBS and control participants under cued certainty and uncertainty (p > .05). Uncertain anticipation compared with certain anticipation induced greater activation of anterior midcingulate cortex, thalamus, and visual processing areas in IBS patients compared with controls. Rectal distention after the uncertain, but not certain, cue induced higher activity in the posterior- and midcingulate cortices and the precuneus in IBS compared with controls. Controls exhibited bilateral insula activation during the nondistention period after the uncertain cue compared with the safe cue. IBS patients failed to produce this response, which was possibly due to elevated bilateral insular responses during nondistention after the safe cue. Brain data were significant at a voxel-level threshold of puncorrected value of less than .005 combined with a cluster-level threshold of pFWE-corrected value of less than .05. Preceding uncertainty differentially modulates the brain processing of physiologically identical rectal stimulation in IBS patients. Cue-dependent alterations in brain responses may underlie hypervigilance to visceral sensations in IBS patients.

Brain processing of rectal sensation in adolescents with functional defecation disorders and healthy controls.

Decreased sensation of urge to defecate is often reported by children with functional constipation (FC) and functional nonretentive fecal incontinence (FNRFI). The aim of this cross-sectional study was to evaluate cerebral activity in response to rectal distension in adolescents with FC and FNRFI compared with healthy controls (HCs). We included 15 adolescents with FC, 10 adolescents with FNRFI, and 15 young adult HCs. Rectal barostat was performed prior to functional magnetic resonance imaging (fMRI) to determine individual pressure thresholds for urge sensation. Subjects received 2 sessions of 5×30seconds of barostat stimulation during the acquisition of blood oxygenation level-dependent fMRI. Functional magnetic resonance imaging signal differences were analyzed using SPM8 in Matlab. Functional constipation and FNRFI patients had higher thresholds for urgency than HCs (P<.001). During rectal distension, FC patients showed activation in the anterior cingulate cortex, dorsolateral prefrontal cortex, inferior parietal lobule, and putamen. No activations were observed in controls and FNRFI patients. Functional nonretentive fecal incontinence patients showed deactivation in the hippocampus, parahippocampal gyrus, fusiform gyrus (FFG), lingual gyrus, posterior parietal cortex, and precentral gyrus. In HCs, deactivated areas were detected in the hippocampus, amygdala, FFG, insula, thalamus, precuneus, and primary somatosensory cortex. In contrast, no regions with significant deactivation were detected in FC patients. Children with FC differ from children with FNRFI and HCs with respect to patterns of cerebral activation and deactivation during rectal distension. Functional nonretentive fecal incontinence patients seem to resemble HCs when it comes to brain processing of rectal distension.