Rectal Distension Research Articles

Cortical evoked potentials in response to rapid balloon distension of the rectum and anal canal.

Neurophysiological evaluation of anorectal sensory function is hampered by a paucity of methods. Rapid balloon distension (RBD) has been introduced to describe the cerebral response to rectal distension, but it has not successfully been applied to the anal canal. Nineteen healthy women received 30 RBDs in the rectum and the anal canal at intensities corresponding to sensory and unpleasantness thresholds, and response was recorded as cortical evoked potentials (CEPs) in 64-channels. The anal canal stimulations at unpleasantness level were repeated after 4min to test the within-day reproducibility. CEPs were averaged, and to overcome latency variation related to jitter the spectral content of single sweeps was also computed. Repeated stimulation of the anal canal generated CEPs with similar latencies but smaller amplitudes compared to those from the rectum. Due to latency jitter, reproducibility of averaged CEPs was lower than what was found in the rectum. The most reproducible feature was N2P2 peak-to-peak amplitude with intra-class correlation coefficient (ICC) of 0.7 and coefficient of variation (CV) of 18%. Spectral content of the single sweeps showed reproducibility with ICCs for all bands >0.8 and corresponding CVs <7%. Cortical potentials evoked from the anal canal are challenged by latency jitter likely related to variability in muscle tone due to the distensions. Using single-sweep analysis, anal CEPs proved to be reproducible and should be used in future evaluation of the anal function.

Impact of planning target volume margins and rectal distention on biochemical failure in image-guided radiotherapy of prostate cancer

Background and purposeA previous study in our department demonstrated the negative impact on freedom from biochemical failure (FFBF) of using too narrow planning target volume (PTV) margins during prostate image-guided radiotherapy (IGRT). Here, we investigated the impact of appropriate PTV margins and rectal distention on FFBF. Methods and materialsA total of 50 T1-T3N0M0 prostate cancer patients were treated with daily IGRT by implanted markers. In the first 25 patients, PTV margins were 3mm laterolateral, 5mm anterioposterior and 4mm craniocaudal. The subsequent 25 patients were treated with isotropic margins of 6mm. The rectal cross-sectional area (CSA) was determined on the planning CT. Median follow-up was 61months. ResultsThe overall 5-year FFBF was 83%. A 6mm PTV margin was related to increased 5-year FFBF on univariate analysis (96% vs 74% with the tighter PTV margins, p=0.04). The 5-year FFBF of patients with a rectal distention on the planning CT was worse compared to those with limited rectal filling (75% for CSA⩾9cm2 vs 89% for CSA<9cm2, p=0.02), which remained significant on multivariate analysis (p=0.04). ConclusionThis retrospective study illustrated the positive impact of PTV margin adaptation and addressed the importance of avoiding rectal distention at time of the planning CT.

Prokinetic effects of mirtazapine on gastrointestinal transit

Mirtazapine is a noradrenergic and specific serotonergic antidepressant. The aim of this study was to investigate the effects of mirtazapine on gastrointestinal motility in dogs, including solid gastric emptying, antral and small intestinal contractions, and small intestinal and colonic transit. Six dogs were implanted with two cannulas located at the duodenum and the ascending colon; another six dogs were implanted with gastric cannula 6 cm proximal to the pylorus. Mirtazapine 45 mg was administered orally 90 min before the study. We found that 1) Mirtazapine accelerated gastric emptying during the entire 3 h in normal dogs (P < 0.04) and accelerated delayed gastric emptying induced by rectal distention (P < 0.04). 2) Mirtazapine restored impaired gastric tone and accommodation induced by rectal distention (P < 0.05). 3) No significant changes were noted in small intestinal contractions or transit with mirtazapine (P > 0.1). 4) Mirtazapine accelerated colonic transit at 2 and 4 h but not 6 h. The geometric center was increased from 1.9 ± 0.6 to 3.0 ± 0.5 and 3.9 ± 0.5 to 4.7 ± 0.1 at 2 and 4 h respectively (P = 0.04 vs. corresponding control). In conclusion, mirtazapine improves gastric emptying in healthy dogs and normalizes rectal distention-induced delay in gastric emptying and accelerates colon but not small intestinal transit in healthy dogs. Clinical studies are warranted to assess the effects of mirtazapine on gastrointestinal motility and sensory functions in patients with functional gastrointestinal diseases.

Colorectal motor and sensory function after hysterectomy

Women may develop constipation after hysterectomy. The pathophysiology and underlying mechanisms are poorly understood. They may originate from either neural damage of rectum and colon or changes in anatomical constellation of the remaining pelvic organs. The aim of this study is to evaluate sensory and motor functions of rectum and colon in women with newly developed constipation after hysterectomy in comparison with women without constipation and healthy controls after hysterectomy . Barostat measurements were performed in posthysterectomy women with constipation (PH-C), without constipation (PH-NC), and healthy controls (n = 10, every group). Outcome measures were rectal and colonic compliance (millilitre per millimetre of mercury), rectocolonic perception in reaction to mechanical distension (millimetre; VAS scores) and rectocolonic reflex (millilitre per millimetre of mercury). No differences in rectal or colonic compliance were observed. Urge perception due to rectal distension increased significantly in controls (from 7 ± 5 to 41 ± 10 mm; p < 0.05) and PH-NC group (from 3 ± 1 to 24 ± 9 mm; p < 0.05), but not in PH-C patients (1 ± 1 to 11 ± 5 mm; ns). In healthy controls and the PN-NC group, respectively, 100 and 70 % of subjects reached the minimal threshold value for urge of 10 mm during the isobaric distension sequence. In the PH-C group, only two subjects (20 %) reached this threshold (p < 0.05). Rectal pain perception, phasic colonic motility and the rectocolonic reflex were intact in all three groups. Colorectal motor and sensory function is generally well preserved in women with constipation after hysterectomy. It is unlikely that the symptom of constipation after hysterectomy has been caused by iatrogenic neuronal damage in these patients.

Enhancing the Placebo Response: Functional Magnetic Resonance Imaging Evidence of Memory and Semantic Processing in Placebo Analgesia

Two groups of patients with irritable bowel syndrome rated pain and underwent functional magnetic resonance imaging brain scanning during experimentally induced rectal distension (20 seconds, 7 stimuli). Group 1 was tested under baseline (natural history [NH]) and a verbally induced placebo condition, whereas Group 2 was tested under baseline and standard placebo (no verbal suggestion for pain reduction) and intrarectal lidocaine conditions. As hypothesized, intrarectal lidocaine reduced evoked pain and pain-related brain activity within Group 2. Between-group comparisons showed that adding a verbal suggestion to a placebo condition increased neural activity involved in memory and semantic processing, areas that process the placebo suggestions. These areas, in turn, are likely to influence brain areas involved in emotions and analgesia and consequently the placebo effect. These placebo suggestions also added significant decreases in activity of brain areas that process pain. The test stimulus itself seems to cue these effects and is consistent with previous explanations that somatic focus and sensory feedback reinforce expectations and other factors that mediate placebo analgesic effects. PerspectiveExpectations for pain can be verbally manipulated to produce placebo analgesia. Placebo analgesia is accompanied by decreased brain activity related to processing pain and increased brain activity that generates placebo analgesia, including semantic and memory regions. Placebo suggestions may enhance placebo analgesia by engaging a feedback mechanism triggered by the painful stimulus itself and related to brain mechanisms involved in memory and semantic processing.

Normal values for high‐resolution anorectal manometry/topography in a healthy Korean population and the effects of gender and body mass index

High-resolution manometry (HRM) based on spatiotemporal plots is increasingly being used. The aim this study was to evaluate, for the first time, the influence of gender, with adjustment for age, body mass index (BMI), and vaginal delivery, on anorectal functions in asymptomatic adults. Fifty-four asymptomatic healthy subjects (M : F = 27 : 27; age = 20-67 years) who were matched by age and gender were enrolled prospectively. We evaluated anorectal pressures, rectal sensation using a HRM probe, and balloon expulsion time. Multivariate linear regression analysis was performed to identify the independent effects of each factor. Anal resting pressure (median [IQR]; 32 [18] vs 46 [17] mmHg, p < 0.001), anal squeeze pressure (75 [28] vs 178 [72] mmHg, p < 0.001), rectal pressure (33 [16] vs 53 [46] mmHg, p = 0.009) and anal pressure (16 [17] vs 30 [36] mmHg, p = 0.019) during simulated evacuation with rectal distention, and the threshold for the desire to defecate (60 [20] vs 80 [60] mL, p = 0.020) were significantly lower in women than in men. BMI was positively correlated with anal resting pressure (95% CI: 0.598-2.947) and negatively correlated with the threshold for first sensation (95% CI: -0.099 to -0.015). Vaginal delivery did not affect any of the anorectal HRM parameters. HRM parameters may be associated with gender and BMI. Therefore, gender and BMI should be taken into consideration when interpreting HRM results.

Towards understanding sex differences in visceral pain: Enhanced reactivation of classically-conditioned fear in healthy women

Sex differences in learned fear regarding aversive gastrointestinal stimuli could play a role in the female preponderance of chronic abdominal pain. In a fear conditioning model with rectal pain as unconditioned stimulus (US), we compared healthy males and females with respect to neural responses during aversive visceral learning, extinction and re-activation of fear memory (i.e., reinstatement). To do so, conditioned visual stimuli (CS+) were consistently paired with painful rectal distensions as US, while different visual stimuli (CS−) were presented without US. During extinction, both CSs were presented without US, whereas during reinstatement, a single, unpaired US was presented. In region-of-interest analyses, sexes were compared with respect to conditioned anticipatory neural activation (CS+>CS−). The results revealed that in late acquisition, CS+ presentation induced significantly greater anticipatory activation of the insula in women. During extinction, women demonstrated reduced activation of the posterior cingulate cortex. During reinstatement, the CS+ led to greater activation of the hippocampus, thalamus and cerebellum in women. These group effects in neural activation during learning and memory processes were not accounted for by sex differences in pain thresholds, pain ratings, or stress parameters. In conclusion, this is the first study to support sex differences in neural processes mediating aversive visceral learning. Our finding of enhanced neural responses during reinstatement in key brain areas relevant for memory suggests enhanced reactivation of old fear memory trace in women. Sex differences in “gut memories” could play a role in the female preponderance of chronic abdominal pain.

Accuracy of High-Resolution MRI with Lumen Distention in Rectal Cancer Staging and Circumferential Margin Involvement Prediction

ObjectiveTo evaluate the accuracy of magnetic resonance imaging (MRI) with lumen distention for rectal cancer staging and circumferential resection margin (CRM) involvement prediction.Materials and MethodsSeventy-three patients with primary rectal cancer underwent high-resolution MRI with a phased-array coil performed using 60-80 mL room air rectal distention, 1-3 weeks before surgery. MRI results were compared to postoperative histopathological findings. The overall MRI T staging accuracy was calculated. CRM involvement prediction and the N staging, the accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were assessed for each T stage. The agreement between MRI and histological results was assessed using weighted-kappa statistics.ResultsThe overall MRI accuracy for T staging was 93.6% (k = 0.85). The accuracy, sensitivity, specificity, PPV and NPV for each T stage were as follows: 91.8%, 86.2%, 95.5%, 92.6% and 91.3% for the group ≤ T2; 90.4%, 94.6%, 86.1%, 87.5% and 94% for T3; 98,6%, 85.7%, 100%, 100% and 98.5% for T4, respectively. The predictive CRM accuracy was 94.5% (k = 0.86); the sensitivity, specificity, PPV and NPV were 89.5%, 96.3%, 89.5%, and 96.3% respectively. The N staging accuracy was 68.49% (k = 0.4).ConclusionMRI performed with rectal lumen distention has proved to be an effective technique both for rectal cancer staging and involved CRM predicting.

A volumetric approach to path-length measurements is essential when treating radiotherapy with modulated beams

The established dosimetric benefits of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy have lead to their increased use in prostate radiotherapy. Complimenting these techniques, volumetric image guidance has supported increased positional accuracy. In addition, 3-dimensional image guidance has also allowed for assessment of potential dosimetric variation that can be attributed to a deformation of either internal or external structures, such as rectal distension or body contour. Compounding these issues is the variation of tissue density through which the new field position passes and also the variation of dose across a modulated beam. Despite the growing level of interest in this area, there are only a limited number of articles that examine the effect of a variation in beam path length, particularly across a modulated field. IMRT and volumetric-modulated radiation therapy (VMAT) fields are dynamic in nature, and the dose gradient within these fields is variable. Assessment of variation of path length away from the beam׳s central axis and across the entire field is vital where there is considerable variation of dose within the field, such as IMRT and VMAT. In these cases, reliance on the traditional central axis to focus skin distances is no longer appropriate. This article discusses these more subtle challenges that may have a significant clinical effect if left unrecognized and undervalued.

Effects of transcutaneous tibial nerve stimulation on anorectal physiology in fecal incontinence: a double‐blind placebo‐controlled cross‐over evaluation

Transcutaneous electrical tibial nerve stimulation (TENS) is of growing interest for the treatment of fecal incontinence (FI), but its mechanism of action remains uninvestigated. We aimed to further assess the anorectal response to TENS in a dynamic model. We performed a placebo-controlled, randomized, double-blinded crossover study in 19 patients suffering from FI to assess the effects of TENS on anorectal function. Anorectal physiology and perception were recorded through two sequences of rectal isobaric distension using an electronic barostat device to measure anal and rectal pressures, rectal volumes, and perception scores. Maximal rectal pressure and volume variation were affected by TENS, with higher mean maximal rectal pressure (5.33 and 4.06 mmHg in the active and sham TENS respectively, p < 0.0001) and lower volume variation (11.45 and 14.7 mL in the active and sham stimulation respectively, p < 0.05). Rectal compliance was not modified by active TENS. Pressure of the upper anal canal was significantly lower with raised isobaric distension in sequences assigned to active TENS. Acute TENS modified anorectal physiology by strengthening the myogenic response to distension rather than increasing muscle relaxation and related rectal compliance in patients with FI.

Sensitivity Testing in Irritable Bowel Syndrome With Rectal Capsaicin Stimulations: Role of TRPV1 Upregulation and Sensitization in Visceral Hypersensitivity?

Abnormal pain perception or visceral hypersensitivity (VH) is considered to be an important mechanism underlying symptoms in a subgroup of irritable bowel syndrome (IBS) patients. Increased TRPV1 (transient receptor potential cation channel subfamily V member 1) expression in rectal biopsies of IBS patients suggests a potentially important role for this nociceptor in the pathophysiology of IBS. However, evidence underscoring the involvement of TRPV1 in visceral perception in IBS is lacking. The objective of this study was to evaluate the role of TRPV1 in VH to rectal distension and clinical symptoms in patients with IBS. A total of 48 IBS patients and 25 healthy volunteers (HVs) were invited to undergo subsequent assessment of sensitivity to rectal distensions and rectal capsaicin applications. Visceral sensitivity was evaluated by rectal distension at 3, 9, and 21 mm Hg above minimal distension pressure (MDP). Capsaicin was applied to the rectal mucosa (0.01%, 0.1%, or solvent only in random order). Visceral sensations (urge to defecate, pain, burning, and warmth sensation) were scored on a 100-mm visual analog scale (VAS). TRPV1 expression in rectal biopsies was determined by immunohistochemistry and real-time PCR. A total of 23 IBS patients (48%) were hypersensitive to rectal distensions (VH-IBS). A concentration-dependent increase of urge and pain perception was present in HVs and IBS patients during capsaicin 0.01 and 0.1% applications. VH-IBS patients experienced a significantly increased perception of pain, but not urge, during capsaicin applications compared with normosensitive patients (ns-IBS) and HVs. Increased pain perception was significantly associated with anxiety and VH, symptoms scores of abdominal pain, loose stools, and stool frequency. Anxiety experienced during the experimental procedure was enhanced in VH-IBS patients but not in ns-IBS or HVs. However, rectal TRPV1 expression was similar in VH-IBS, ns-IBS, and HVs on both mRNA and protein expression levels. TRPV1 expression levels did not correlate with pain perception to capsaicin or clinical symptoms in IBS patients or the subgroups. IBS patients with VH to rectal distension reveal increased pain perception to rectal application of capsaicin, as well as an increased anxiety response. No evidence for TRPV1 upregulation could be demonstrated. As both VH and anxiety are independently associated with increased pain perception to rectal capsaicin application, our data suggest that both peripheral and central factors are involved, with increased receptor sensitivity as a speculative possibility.

Systematic review: anal and rectal changes after radiotherapy for prostate cancer

Pelvic radiotherapy may lead to changes of anorectal function resulting in incontinence-related complaints. The aim of this study was to systematically review objective findings of late anorectal physiology and mucosal appearance after irradiation for prostate cancer. MEDLINE, EMBASE, and the Cochrane library were searched. Original articles in which anal function, rectal function, or rectal mucosa were examined ≥3 months after EBRT for prostate cancer were included. Twenty-one studies were included with low to moderate quality. Anal resting pressures significantly decreased in 6 of the 9 studies including 277 patients. Changes of squeeze pressure and rectoanal inhibitory reflex were less uniform. Rectal distensibility was significantly impaired after EBRT in 7 of 9 studies (277 patients). In 4 of 9 studies on anal and in 5 of 9 on rectal function, disturbances were associated with urgency, frequent bowel movements or fecal incontinence. Mucosal changes as assessed by the Vienna Rectoscopy Score revealed telangiectasias in 73 %, congestion in 33 %, and ulceration in 4 % of patients in 8 studies including 346 patients, but no strictures or necrosis. Three studies reported mucosal improvement during follow-up. Telangiectasias, particularly multiple, were associated with rectal bleeding. Not all bowel complaints (30 %) were related to radiotherapy. Low to moderate quality evidence indicates that EBRT reduces anal resting pressure, decreases rectal distensibility, and frequently induces telangiectasias of rectal mucosa. Objective changes may be associated with fecal incontinence, urgency, frequent bowel movements, and rectal bleeding, but these symptoms are not always related to radiation damage.

Argon Plasma Coagulation Therapy Versus Topical Formalin for Intractable Rectal Bleeding and Anorectal Dysfunction After Radiation Therapy for Prostate Carcinoma

To evaluate and compare the effect of argon plasma coagulation (APC) and topical formalin for intractable rectal bleeding and anorectal dysfunction associated with chronic radiation proctitis. Thirty men (median age, 72 years; range, 49-87 years) with intractable rectal bleeding (defined as ≥1× per week and/or requiring blood transfusions) after radiation therapy for prostate carcinoma were randomized to treatment with APC (n=17) or topical formalin (n=13). Each patient underwent evaluations of (1) anorectal symptoms (validated questionnaires, including modified Late Effects in Normal Tissues-Subjective, Objective, Management, and Analytic and visual analogue scales for rectal bleeding); (2) anorectal motor and sensory function (manometry and graded rectal balloon distension); and (3) anal sphincteric morphology (endoanal ultrasound) before and after the treatment endpoint (defined as reduction in rectal bleeding to 1× per month or better, reduction in visual analogue scales to ≤25 mm, and no longer needing blood transfusions). The treatment endpoint was achieved in 94% of the APC group and 100% of the topical formalin group after a median (range) of 2 (1-5) sessions of either treatment. After a follow-up duration of 111 (29-170) months, only 1 patient in each group needed further treatment. Reductions in rectal compliance and volumes of sensory perception occurred after APC, but no effect on anorectal symptoms other than rectal bleeding was observed. There were no differences between APC and topical formalin for anorectal symptoms and function, nor for anal sphincteric morphology. Argon plasma coagulation and topical formalin had comparable efficacy in the durable control of rectal bleeding associated with chronic radiation proctitis but had no beneficial effect on anorectal dysfunction.

Technique of Functional and Motility Test: How to Perform Biofeedback for Constipation and Fecal Incontinence

Biofeedback therapy is an instrument-based learning process centered on operant conditioning. The goal of biofeedback therapy in defecatory disorders is to strengthen the pelvic floor muscles, retrain rectal sensation and coordinate pelvic floor muscles during evacuation. Biofeedback therapy, in a broader sense, includes education, counseling, and diaphragmatic muscle training as well as exercise, sensory, and coordination training. For dyssynergic defecation, biofeedback therapy is a well-known and useful treatment option that had response rates of approximately 70-80% in randomized controlled trials. Biofeedback therapy for dyssynergic defecation consists of improving the abdominal push effort together with biofeedback technique-guided pelvic floor relaxation followed by simulated defecation and/or sensory training. For fecal incontinence, the results of a randomized controlled trial, which had a response rate of 76%, indicated that biofeedback therapy is useful in selected patients who fail to respond to conservative treatment and that training to enhance rectal discrimination of sensation may be helpful in reducing fecal incontinence. The focus of biofeedback therapy for fecal incontinence is on exercising external sphincter contractions under instant feedback, either alone or synchronously with rectal distension and/or sensory training. Biofeedback therapy is a safe treatment that may produce durable improvement beyond the active treatment period; however, a well-designed study to establish a standard protocol for biofeedback therapy is needed. This review discusses the technique of biofeedback therapy to achieve the goal and clinical outcomes for constipation and fecal incontinence.

Anorectal toxicity of external beam radiotherapy in the treatment of prostate cancer

Introduction: Maximising radiotherapy dosage is associated with better tumour response in prostate cancer. High dose three-dimensional conformal radiotherapy (3D CRT) has allowed dose escalation to be safely achieved and the current standard dose in the UK with this technique is 74 Grays (Gy). Documenting normal tissue tolerance is critical and forms the basis of this prospective study of anorectal toxicity. Patients and methods: Seventeen consecutive men (median age 72 (range 50–79) years) with localised or locally advanced prostate cancer treated with 74 Gy of 3D CRT were studied. Wexner incontinence scores, comprehensive anorectal physiology and endoanal ultrasound were measured before and four months after completing treatment. Results: Wexner incontinence scores increased from a median of 0 to 1 (range 0–6) with treatment ( p=0.001). Patients developed faecal urgency (7/17), passive faecal loss (5/17) or a combination of both (3/17) as new anorectal symptoms. No patients reported episodes of frank faecal incontinence. A significant decline in rectal mucosal electrosensitivity (mean (standard deviation (SD)) thresholds increasing from 24.7 (10.7) to 34.3 (9.3) mA after treatment, p=0.003) and an increase in rectal elastance (mean (SD) of 0.056 (0.03) mm Hg/ml to 0.078 (0.036) mm Hg/ml pre- and post-treatment respectively, p=0.0181) was seen. No changes in anal canal manometry, rectal distension volumes and endoanal ultrasound were noted. Conclusions: Early anorectal symptoms are common after 3D CRT for prostate cancer. Rectal injury is evident with an increase in wall stiffness and a decrease in mucosal sensitivity. Longer term studies monitoring anorectal toxicity are warranted.

Does Rectal Distention Affect Interfractional Dose to Prostate and Rectum in Prostate IMRT Treatment?: Optimizing IGRT Techniques

Rectal distention and prostate movement has the potential to alter planned radiation dose delivery. Image guided radiation therapy in conjunction with varying fusion techniques allow us to calculate interfractional dose differences due to internal organ movement.

Who Needs Adaptive Radiation Therapy When You Can Do Internal Anatomy Positioning?: A Review of Daily Cone Beam Computed Tomography (CBCT) Scans to Analyze Geometric Dose Variation Due to Daily Rectal Variation and Distension in Postprostatectomy Radiation

Who Needs Adaptive Radiation Therapy When You Can Do Internal Anatomy Positioning?: A Review of Daily Cone Beam Computed Tomography (CBCT) Scans to Analyze Geometric Dose Variation Due to Daily Rectal Variation and Distension in Postprostatectomy Radiation

A New Dietary and Laxative Protocol Reduces Rectal Distension and Acute Rectal Toxicity in Prostate Cancer Patients Treated by Radiation Therapy

A New Dietary and Laxative Protocol Reduces Rectal Distension and Acute Rectal Toxicity in Prostate Cancer Patients Treated by Radiation Therapy

Biological and psychological predictors of visceral pain sensitivity in healthy premenopausal women

Factors that are associated with pain perception remain incompletely understood, especially in the visceral pain field. Therefore, the current study aimed to investigate possible psychological and biological predictors of visceral pain sensitivity in healthy subjects. In a sample of 59 healthy premenopausal female subjects on hormonal contraceptives, measures of gastrointestinal (GI) symptoms in daily life, trait and state anxiety, depression, serum cortisol concentrations and serum levels of interleukin-6 (IL-6) were obtained, followed by assessment of rectal distension pain sensitivity measures (i.e., rectal distension sensory threshold, pain threshold and pain ratings for discrete rectal distension stimuli). Regression analyses showed that more GI symptoms in daily life predicted a lower pain threshold. Higher levels of state anxiety predicted a lower pain threshold. Higher cortisol concentrations predicted lower pain ratings. IL-6 was positively related to GI symptoms but was a non-significant predictor of pain threshold in the multiple regression analysis. Similar to findings in patients with functional GI symptoms, we showed that subclinical GI symptoms predict visceral pain sensitivity. In line with somatic pain findings, state but not trait anxiety was found to predict visceral pain sensitivity. Our finding on serum cortisol as positive predictor of pain sensitivity might be interpreted in light of immunosuppressive effects of cortisol. Our finding on the role of IL-6 in GI symptoms is promising for understanding GI complaints in patients and needs further investigation.

154. Can we predict visceral pain sensitivity? An experimental study in healthy women

Patients and healthy subjects show large inter-individual differences in visceral pain sensitivity, which may have pathophysiological relevance. However, the factors contributing to differences in pain sensitivity remain poorly understood. Thus, this study aimed to investigate psychological and biological predictors of visceral pain sensitivity in healthy subjects. Methods : In N = 59 healthy young females, psychological (i.e., state and trait anxiety, depression) and biological (i.e., gastrointestinal (GI) symptoms in daily life, serum cortisol, and serum levels of interleukin (IL)-6) were collected, followed by assessment of rectal distension pain sensitivity. To do so, rectal distension sensory and pain thresholds, and pain ratings for discrete rectal distension stimuli at pain threshold level were assessed. Results : Regression analyses revealed that lower pain thresholds were predicted by higher state anxiety and more GI symptoms in daily life (both p < .05). Increased pain ratings were predicted by lower cortisol levels ( p < .05). Additional correlation analyses showed that lower sensory thresholds were associated with GI symptoms ( p < .05). Conclusions : We observed that psychological (state anxiety) and biological (cortisol levels, subclinical GI symptoms) variables predict different aspects of visceral pain sensitivity, which is in line with results from studies in somatic pain. Our findings may help to refine our understanding of predictors and/ or risk factors for visceral pain hypersensitivity, which may contribute to the pathophysiology of visceral pain syndromes such as Irritable Bowel Syndrome.