Alterations in cerebral potentials evoked by rectal distention and drinking ice water in patients with irritable bowel syndrome

AIM: Visceral hypersensitivity has been found to be present in irritable bowel syndrome (IBS). The current study sought to study visceral afferent hypersensitivity in IBS patients and obtain further objective evidence of alterations in intestinal afferent pathways in IBS patients by cerebral evoked potentials (CEP). METHOD: We studied 30 female IBS patients and 12 female healthy subjects. Rectal perception thresholds to balloon distention were measured and CEP was recorded in response to rhythmic rectal distention (two distention series, each of 100 repetitions at a frequency of 1 Hz) at the volume of perception thresholds. All subjects were then asked to drink 220 mL 4 degrees C ice water and the above steps were repeated 20 min later. RESULTS: Rectal distention led to recognizable and reproducible CEP. Compared to healthy subjects, IBS patients demonstrated significantly shorter N1, P1 and N2 latencies (P < 0.05). After drinking ice water, IBS patients exhibited further shortened N1, P1 and N2 latencies (P < 0.05), but drinking did not alter the latencies of healthy controls and the amplitudes of both IBS patients and healthy controls. CONCLUSION: The shorter latency of cerebral potentials evoked by rectal distention and ice water stimulation in IBS patients provided further objective evidence for defective visceral afferent transmission in IBS patients.     

肠易激综合征患者直肠扩张后脑诱发电位的研究

目的 通过比较直肠扩张后脑诱发电位(CEP)的改变,探讨肠易激综合征(IBS)患者内脏高敏感性的发生机制,旨在进一步获得IBS感觉传入通路异常的客观依据。方法 根据罗马Ⅱ标准选择女性IBS患者10例,其中腹泻型6例,便秘型2例,腹泻-便秘交替型2例,另设7例女性健康志愿者为对照组,对其进行直肠气囊扩张,首先测出每例受试者感觉阈值,用1.5倍该阈值空气体积作为刺激(频率1Hz,连续100次,休息10分钟,重复一次),启动并记录两组受试者CEP的变化。结果 直肠节律性机械扩张引出可识别、可复制的CEP。与健康对照者相比,IBS患者N_1,P_1,N_2潜伏期明显缩短(P<0.05),同时,峰间波幅有增大趋势,但无统计学意义(P>0.05)。结论 IBS患者经直肠扩张后产生的CEP的改变证实了其内脏高敏感性及内脏传入通路的异常。     

Alterations in cerebral potentials evoked by rectal distension in irritable bowel syndrome

OBJECTIVE: Central nervous system correlates of the visceral hyperalgesia documented in patients with irritable bowel syndrome are limited. Reproducible cerebral evoked potentials can be recorded in response to rhythmic balloon distension of the rectum in healthy adults. Irritable bowel syndrome patients and healthy subjects were studied to compare the characteristics of mechanically-evoked rectal cerebral potentials obtained during fasting and after the ingestion of a standard meal. METHODS: Twenty-two pairs of age-matched healthy female subjects and female irritable bowel syndrome patients were studied. Cerebral evoked potentials were recorded in response to rhythmic rectal distension (two distension series each of 100 repetitions at 0.8 hertz); cerebral evoked potential recordings were repeated after a 1000 kcal (46% fat) liquid meal. Trait and state anxiety questionnaires were also completed. RESULTS: Compared to healthy subjects, irritable bowel syndrome patients demonstrated higher prevalence of cerebral evoked potential early peaks (latency < 100 ms) postprandially, and uniformly shorter cerebral evoked potential latencies both before and after feeding. CONCLUSION: These findings provide further objective evidence for defective visceral afferent transmission in irritable bowel syndrome patients.     

Rectal Hypersensitivity Reduced by Acupoint TENS in Patients with Diarrhea-Predominant Irritable Bowel Syndrome: A Pilot Study

Our aim was to compare rectal perception of patients with diarrhea-predominant irritable bowel syndrome (IBS-D), constipation-predominant irritable bowel syndrome (IBS-C), functional constipation (FC), and healthy controls and to evaluate the therapeutic effect of acupoint transcutaneous electric nerve stimulation (TENS). Age- and sex-matched patients (24 IBS-D, 20 IBS-C, and 30 FC) were selected, and 30 volunteers served as healthy controls. Rectal sensory thresholds were evaluated by rectal balloon distension. Short- and long-term acupoint TENS was given respectively. IBS-D patients had significantly lower rectal sensory thresholds of the first sensation of stool, urgency of defecation, and pain than IBS-C or FC patients or healthy controls (P < 0.05), but there were no differences in rectal sensory thresholds among IBS-C and FC patients and healthy controls. In each group, females had significantly lower rectal sensory thresholds than males (P < 0.05), but there was no difference between younger (< or = 50 years old) and older (> 50 years old) patients. Short-term acupoint TENS increased rectal sensory thresholds of IBS-D patients. After 2-month acupoint TENS treatment in IBS-D patients, rectal sensory thresholds were significantly increased, stool times and the intensity of abdominal pain were decreased, and psychological scores were relieved to normal. Lowered rectal perception threshold is a hallmark of IBS-D patients. Females have significantly lower rectal sensory thresholds than males. Acupoint TENS is effective to treat IBS-D.     

肠易激综合征内脏感觉过敏大鼠脊髓诱发电位的研究

背景:内脏感觉过敏是肠易激综合征(IBS)的主要发病机制之一,临床上缺乏客观、无创的内脏敏感性检测方法。目的:建立直肠球囊扩张下脊髓诱发电位(SEP)的检测方法,并通过IBS内脏感觉过敏大鼠与正常大鼠的比较以及雌雄大鼠之间的比较,取得IBS存在内脏感觉过敏的客观证据。方法:通过直肠球囊有节律的充气、放气,给予直肠一定频率的反复刺激,记录诱发得到的脊髓相应节段(L6～S2)的SEP。结果:实验组雌雄大鼠分别与对照组同性别大鼠相比,SEP各波潜伏期显著缩短(P<0.05),峰间波幅显著增高(P<0.01)。实验组雌性大鼠的各波潜伏期显著短于雄性大鼠(P<0.05),峰间波幅也低于雄性大鼠(P<0.05);对照组雌性与雄性大鼠的各波潜伏期和峰间波幅无显著差异。结论:通过有节律的直肠球囊扩张,能诱发得到重复性好、易识别的SEP,可作为内脏敏感性的客观依据。     

直肠内温度变化影响肠易激综合征患者内脏感觉阈值

目的 探讨直肠内温度及压力变化对肠易激综合征(IBS)患者内脏感觉阈值的影响，进一步研究IBS的发病机制。方法 通过直肠球囊内注入空气(压力刺激)、38℃温水、4℃冰水(温度刺激)及脐部放置冰袋加直肠球囊内充气，研究直肠温度和压力变化刺激对初始感觉阈值和排便阈值的影响。结果 (1)直肠球囊内注气后，IBS组患者的初始感觉阈值明显低于对照组，排便阈值差异不明显。IBS组中腹泻型与交替型患者的初始感觉阈值及排便阈值均明显降低；便秘型患者的初始感觉阈值稍低于对照组，排便阈值明显增高。(2)直肠球囊内注入4℃冰水后，除便秘型IBS的排便阈值稍有所增加外，其余患者初始感觉阈值及排便阈值均显著降低，以腹泻型变化最明显。(3)脐部放置冰袋可诱发部分患者产生症状，但对初始感觉阈值和排便阈值无明显影响。结论 直肠温度和压力刺激可明显降低IBS患者的初始感觉阈值和排便阈值，以腹泻型患者最显著。内脏对压力和温度的敏感性增高可能是IBS发病的重要机制之一。     

Rectal function and bowel habit in irritable bowel syndrome

OBJECTIVES: Rectal compliance may influence rectal perception, but their functional implications remain incompletely understood. Our aim was to determine whether rectal function is related to bowel habit in the irritable bowel syndrome. METHODS: The responses to fixed tension rectal distension applied by means of a tensostat were compared among constipation-predominant (n = 9), diarrhea-predominant (n = 7), alternating habit (n = 11) irritable syndrome subgroups, and healthy controls (n = 15). RESULTS: Overall, patients had normal rectal compliance and increased perception, but compliance was lower in diarrhea-predominant as compared to constipation-predominant patients (6.7 +/- 0.7 ml/mmHg vs. 9.9 +/- 0.7 ml/mmHg, respectively; p < 0.05) and perception was higher (39 +/- 6 g vs. 64 +/- 9 g tolerance, respectively; p < 0.05). CONCLUSION: Distinctive tensosensitivity and compliance characterize rectal function in irritable bowel syndrome subgroups with different bowel habit.     

Sensitivity disturbances in patients with irritable bowel syndrome and fibromyalgia

BACKGROUND: Although visceral hypersensitivity is a common feature among patients with irritable bowel syndrome (IBS), studies on somatic sensitivity have given controversial results. AIM: To assess visceral sensitivity in response to isotonic rectal distensions and somatic sensitivity at different layers of the body wall (skin, subcutis, and muscle) in patients with IBS and fibromyalgia (FM), within and outside the area of abdominal pain referral. MATERIALS AND METHODS: We studied 10 patients with IBS, 5 patients with FM, 9 patients with IBS+FM, and 9 healthy controls. Rectal distensions were performed by increasing tension at 4 g steps up to 64 g or discomfort. Pain thresholds to electrical stimulation were measured within and outside the areas of abdominal pain referral. RESULTS: Patients with IBS and IBS+FM demonstrated rectal hypersensitivity in comparison to controls. The threshold of discomfort was 44 +/- 5 g in IBS and 36 +/- 5 in IBS+FM patients, while patients with FM and healthy controls tolerated all distensions without discomfort. In the areas of pain referral, pain thresholds of all three tissues of the body wall were lower than normal in all patients groups (p < 0.001). In control areas, the pain thresholds were normal in skin, and lower than normal in subcutis and muscle in IBS (p < 0.001). FM and IBS+FM demonstrated somatic hypersensitivity at all sites (p < 0.001 vs healthy). CONCLUSION: Our observations seem to indicate that, although sharing a common hypersensitivity background, multiple mechanisms may modulate perceptual somatic and visceral responses in patients with IBS and FM.     

Visceral hypersensitivity following cold water intake in subjects with irritable bowel syndrome

Background Visceral hypersensitivity has been shown to be present in irritable bowel syndrome (IBS). This study sought to investigate rectal sensitivity and abdominal symptoms in IBS patients before and after 220 ml cold water intake. Methods A total of 60 IBS patients and 18 healthy controls participated in this study. Both the perception thresholds and defecation thresholds to rectal balloon distension were measured. Then, all subjects were asked to drink 220 ml 37°C warm water or 4°C cold water, and these steps were repeated 20 min later. Symptoms including abdominal pain/discomfort, bloating, and diarrhea were recorded during the study. Results Compared with the controls, the thresholds of initial sensation to rectal balloon distention in IBS patients were significantly lower while the defecation thresholds were higher in constipation-predominant IBS patients. After drinking cold water, the perception thresholds in IBS patients and the defecation thresholds in diarrhea-predominant IBS patients were further decreased. However, warm water intake did not change the perception thresholds significantly in either IBS patients or controls. A negative linear correlation was found between the symptoms and the visceral perception thresholds in diarrhea-predominant IBS patients who showed significant symptoms after cold water intake. Conclusion The results indicated that cold water intake leads to lowered visceral perception thresholds in IBS patients that were inversely relevant to the abdominal symptoms in symptomatic diarrhea-predominant IBS patients. The alteration of rectal sensitivity and abdominal symptoms following cold water stimulation provided further objective evidence for visceral hypersensitivity in IBS patients.     

Cerebral response to electric stimulation of the colon and abdominal skin in healthy subjects and patients with irritable bowel syndrome.

BACKGROUND: Visceral hyperalgesia may play an important part in the pathophysiology of the irritable bowel syndrome (IBS). We investigated the neuronal afferent pathways in healthy volunteers and IBS patients by recording evoked potentials (EPs) elicited by electrical stimulation of the colon and abdominal skin inside and outside the referred pain area. METHODS: Six healthy subjects and nine IBS patients met the inclusion criteria. Morphology and topography of EPs to painful electrical stimuli were estimated in the rectosigmoid junction and on the skin inside/outside the referred pain areas. RESULTS: The EPs to painful stimuli of the gut showed a shorter latency and a smaller amplitude of the first positive peak (P1) in the IBS group. The controls had a mid-latency frontal positive component after 100 ms, whereas no reliable early activation was seen in the IBS patients. In controls, a single late (>150 ms) positive component was seen, whereas the late component was biphasic in the IBS group. The EPs to painful stimuli of the two skin areas differed in IBS patients, but not in controls. CONCLUSION: Differences in the EPs to electrical painful stimulation of the sigmoid colon and skin inside/outside the experimentally evoked referred pain area were seen comparing healthy subjects and IBS patients. The results indicate altered central nervous system responses.     

Abnormal endogenous pain modulation and somatic and visceral hypersensitivity in female patients with irritable bowel syndrome

AIM： To investigate the role of endogenous pain modulatory mechanisms in the central sensitization implicated by the visceral hypersensitivity demonstrated in patients with irritable bowel syndrome （IBS）. Dysfunction of modulatory mechanisms would be expected to also result in changes of somatic sensory function.
METHODS： Endogenous pain modulatory mechanisms were assessed using heterotopic stimulation and somatic and visceral sensory testing in IBS. Pain intensities （visual analogue scale, VAS 0-100） during suprathreshold rectal distension with a barostat, cold pressor stimulation of the foot and during both stimuli simultaneously （heterotopic stimulation） were recorded in 40 female patients with IBS and 20 female healthy controls.
RESULTS： Rectal hypersensitivity （defined by 95% Cl of controls） was seen in 21 （53%）, somatic hypersensitivity in 22 （55%） and both rectal and somatic hypersensitivity in 14 of these IBS patients. Heterotopic stimulation decreased rectal pain intensity by 6 （-11 to -1） in controls, but increased rectal pain by 2 （-3 to ＋6） in all IBS patients （P 〈 0.05） and by 8 （-2 to ＋19） in IBS patients with somatic and visceral hypersensitivity （P 〈 0.02）.
CONCLUSION： A majority of IBS patients had abnormal endogenous pain modulation and somatic hypersensitivity as evidence of central sensitization.     

Visceral perception thresholds after rectal thermal and pressure stimuli in irritable bowel syndrome patients

BACKGROUND AND AIM: Visceral hypersensitivity has been shown to be present in irritable bowel syndrome (IBS). The current study sought to compare the characteristics of visceral perception thresholds after rectal thermal and pressure stimuli between IBS patients and healthy subjects. METHODS: A total of 46 patients with IBS were diagnosed using Rome II criteria. Thirteen healthy individuals participated in the study. Rectal visceral perception thresholds were examined in patients with IBS and in normal controls after thermal and pressure stimuli. Subjects were asked to report the sensation type, location, and spread. RESULTS: Compared with healthy subjects, IBS patients demonstrated significantly initially lower perception thresholds and defecation thresholds to rectal thermal and pressure stimuli, particularly in patients with diarrhea-predominant IBS. Ice stimuli on the abdominal wall had varied effects on symptoms in patients with IBS and did not affect perception thresholds. CONCLUSIONS: Visceral perception thresholds were decreased significantly after rectal thermal and pressure stimuli in patients with IBS. Visceral hypersensitivity may be one of the important pathogenic mechanisms in IBS.     

Cerebral Response to Electric Stimulation of the Colon and Abdominal Skin in Healthy Subjects and Patients with Irritable Bowel Syndrome

Background: Visceral hyperalgesia may play an important part in the pathophysiology of the irritable bowel syndrome (IBS). We investigated the neuronal afferent pathways in healthy volunteers and IBS patients by recording evoked potentials (EPs) elicited by electrical stimulation of the colon and abdominal skin inside and outside the referred pain area. Methods: Six healthy subjects and nine IBS patients met the inclusion criteria. Morphology and topography of EPs to painful electrical stimuli were estimated in the rectosigmoid junction and on the skin inside/outside the referred pain areas. Results: The EPs to painful stimuli of the gut showed a shorter latency and a smaller amplitude of the first positive peak (P1) in the IBS group. The controls had a mid-latency frontal positive component after 100 ms, whereas no reliable early activation was seen in the IBS patients. In controls, a single late (> 150 ms) positive component was seen, whereas the late component was biphasic in the IBS group. The EPs to painful stimuli of the two skin areas differed in IBS patients, but not in controls. Conclusion: Differences in the EPs to electrical painful stimulation of the sigmoid colon and skin inside/outside the experimentally evoked referred pain area were seen comparing healthy subjects and IBS patients. The results indicate altered central nervous system responses.     

Patients with irritable bowel syndrome have greater pain tolerance than normal subjects

A low tolerance for pain has been postulated as a factor in the expression of symptoms in patients with irritable bowel syndrome. This has been based on previous work demonstrating reduced intestinal thresholds for rectal pain induced by balloon distention in patients with irritable bowel syndrome. As the disease may alter the rectal response to distention, inferences regarding pain perception and reporting behavior cannot be drawn from these data. In this study, using electrocutaneous stimulation, we found that patients with irritable bowel syndrome had pain reporting behavior comparable to patients with Crohn's disease. Both patient groups were less likely than normals to report a noxious stimulus as painful. This suggests that pain perception and reporting is attenuated in patients with chronic abdominal pain and, accordingly, a generalized reduction in the threshold for reporting pain is not a factor in the expression of symptoms in the irritable bowel syndrome.     

Oesophageal sensation assessed by electrical stimuli and brain evoked potentials--a new model for visceral nociception.

Sensory thresholds and brain evoked potentials were determined in 12 healthy volunteers using electrical stimulation of the oesophagus 28 and 38 cm from the nares. The peaks of the evoked potentials were designated N for negative deflections and P for positive. Continuous electrical stimulation (40 Hz) at the 38 cm position resembled heartburn (five of 12 subjects) while non-specific ('electrical') sensations were provoked at 28 cm (10 of 12). Thresholds of sensation and of pain were lower at the initial than the second determination, but did not differ with respect to stimulation site. The pain summation threshold to repeated stimuli (2 Hz, 5 stimuli) was determined for the first time in a viscus. This threshold was lower than the pain threshold to single stimuli at 38 cm (p < 0.02). Evoked potential latencies did not change significantly over a six month period while the N1/P2 amplitude was higher at the first measurement (p < 0.05). P1 and N1 latencies were significantly shorter 38 cm (medians 100 and 141 ms) than 28 cm from the nares (102 and 148 ms) (p = 0.04 and p = 0.008). Electrical stimulation of the oesophagus may serve as a human experimental model for visceral pain. Longer evoked potential latencies from the proximal compared with distal stimulations provide new information about the sensory pathways of the oesophagus.     

Novel techniques to study visceral hypersensitivity in irritable bowel syndrome

Visceral hypersensitivity has emerged as a key hypothesis in explaining the painful symptoms of irritable bowel syndrome (IBS), and it has been proposed as a “biologic marker” for the condition. Visceral hypersensitivity can be influenced by peripheral and central mechanisms affecting pain perception. The optimal method for its assessment in humans has not been determined. Current techniques include stimulation via the computerized barostat and electrical stimulation, response measures including the lower limb reflex, and brain imaging modalities such as functional MRI and positron emission tomography. It has been shown that IBS patients have decreased sensory thresholds to colonic and rectal balloon distention by barostat. Studies using electrical stimulation and the RIII lower limb reflex have further confirmed enhanced visceral perception in IBS. Evidence from more recent neuroimaging studies suggests that IBS patients have abnormal activation of brain circuits involved in emotional and cognitive modulation of sensory information, resulting in ineffective pain modulation; these circuits may have a pathophysiologic role in enhancing visceral perception. There are few effective pharmacologic treatments that relieve IBS symptoms, and improved understanding of brain-gut interactions and factors relating to enhanced visceral perception may guide us in developing more efficacious treatments.     

Enhanced perception of physiological intestinal motility in the irritable bowel syndrome

An increased awareness of intestinal distention or contraction is implicated in the pathogenesis of the irritable bowel syndrome. This study aimed to test this hypothesis in 20 patients with the irritable bowel syndrome and 10 controls by relating the reporting of abdominal sensations to the occurrence of the duodenal phase 3 activity front of the migrating motor complex. During prolonged recordings of interdigestive small bowel motility, subjects were asked to report any episodes of abdominal sensation they experienced. Diurnally, the rate of occurrence of abdominal sensation was significantly greater in patients with the irritable bowel syndrome than in controls (P less than 0.001); such episodes were coincident with a duodenal activity front in 9 patients with the irritable bowel syndrome and in 1 control (P less than .05). Moreover, the rate of occurrence of episodes of sensation was greater (P less than 0.01) during diurnal phase 3 activity than during diurnal phase 2 activity. When episodes were coincident with duodenal phase 3 activity, these activity fronts were of significantly greater amplitude (irritable bowel syndrome: median, 23 mm Hg) than "noncoincident" activity fronts (median, 17 mm Hg; P less than 0.05) in both patients and controls. These data strongly suggest that certain physiological small bowel motor events, if of sufficient contraction amplitude, are able to be perceived by a greater proportion of irritable bowel syndrome patients and with greater frequency than by healthy subjects. The authors conclude that the threshold for perception of intestinal contraction is lower than normal in at least some patients with the irritable bowel syndrome.     

Stimulation of the nitric oxide-guanosine 3', 5'-cyclic monophosphate pathway by sildenafil: effect on rectal muscle tone, distensibility, and perception in health and in irritable bowel syndrome

OBJECTIVES: Nitric oxide, a neurotransmitter in the noncholinergic, nonadrenergic nervous system, is a mediator of relaxation of GI smooth muscle and of visceral nociception mainly studied in vitro. Sildenafil stimulates the nitric oxide guanosine 3', 5'-cyclic monophosphate (NO-cGMP) pathway through inhibition of phosphodiesterase 5. The aims of this study were to evaluate in vivo the effect of stimulation of the NO-cGMP pathway on rectal tone, distensibility, and perception in healthy individuals and in patients with irritable bowel syndrome (IBS). METHODS: In eight healthy subjects and four patients with IBS rectal tone, distensibility and perception thresholds were measured with an electronic barostat both before and 60 min after administration of sildenafil (50 mg p.o.). Perception was scored on a graded scale of 0-6. At the end of a distension series an anatomic questionnaire was filled out by the subjects. RESULTS: Sildenafil significantly reduced rectal tone in healthy subjects (intrabag volume predrug: 145.5 +/- 18.7 ml vs postdrug: 164.4 +/- 16.9 ml, p = 0.01) and IBS (111.3 +/- 25.2 ml vs 136.5 +/- 33.3 ml; p = 0.01) but did not alter rectal compliance (healthy subjects: 5.8 +/- 0.4 vs 6.3 +/- 0.6 ml/mm Hg, p > 0.05; IBS subjects: 6.1 +/- 0.6 vs 7.1 +/- 1.0 ml/mm Hg, p > 0.05). Intrabag pressure and rectal wall tension to reach perception thresholds for initial sensation, sensation of stool, and urgency were not altered by sildenafil. However, intrabag volumes to reach these thresholds were significantly increased by sildenafil both in healthy subjects and in patients with IBS. Viscerosomatic referral was unchanged. CONCLUSIONS: Stimulation of the NO-cGMP pathway decreases rectal tone but does not influence rectal distensibility. Relaxation of the rectum is accompanied by an increase in rectal volumes to reach perception thresholds in healthy subjects and in patients with IBS, but no direct effect on rectal perception can be demonstrated.     

Anorectal manometry in irritable bowel syndrome: differences between diarrhoea and constipation predominant subjects.

Anorectal manometry with balloon distension was performed on 28 patients with diarrhoea predominant irritable bowel syndrome, 27 patients with constipation predominant irritable bowel syndrome and 30 normal controls. In the diarrhoea predominant group balloon volumes required to perceive the sensations of gas, stool, urgency of defecation and discomfort were significantly lower than in controls or constipation predominant patients (p less than 0.001). Diarrhoea predominant patients also had a significantly lower rectal compliance than controls or constipation predominant patients (p less than 0.03) but showed no difference in motor activity induced by distension. When the constipation predominant patients were compared with controls the only significant difference that emerged was in the volume at which discomfort was perceived. No significant differences between constipated subjects and controls were found in the distension induced motor activity. Symptom severity and psychological parameters were also recorded and the diarrhoea predominant patients were found to be more anxious than those with constipation (p = 0.04). It proved possible (by comparison with the control group) to identify three abnormal rectal subtypes in patients with irritable bowel syndrome. These were a sensitive rectum (low sensation thresholds, normal or low rectal pressure), a stiff rectum (normal or low sensation thresholds, high pressure) and an insensitive rectum (high sensation thresholds, normal or high pressure) and their distribution varied considerably depending on bowel habit. Some form of rectal abnormality was identified in 75% of diarrhoea predominant patients compared with 30% of constipation predominant subjects (p = 0.002). A sensitive rectum was a particular feature of diarrhoea predominant patients being observed in 57% of patients compared with only 7% of the constipated group (p less than 0.001).     

Changes in rectal sensitivity after hypnotherapy in patients with irritable bowel syndrome.

Fifteen patients with the irritable bowel syndrome were studied to assess the effect of hypnotherapy on anorectal physiology. In comparison with a control group of 15 patients who received no hypnotherapy significant changes in rectal sensitivity were found in patients with diarrhoea-predominant irritable bowel syndrome both after a course of hypnotherapy and during a session of hypnosis (p less than 0.05). Although patient numbers were small, a trend towards normalisation of rectal sensitivity was also observed in patients with constipation-predominant irritable bowel syndrome. No changes in rectal compliance or distension-induced motor activity occurred in either subgroup nor were any changes in somatic pain thresholds observed. The results suggest that symptomatic improvement in irritable bowel syndrome after hypnotherapy may in part be due to changes in visceral sensitivity.