SEARCH

SEARCH BY CITATION

Keywords:

  • irritable bowel syndrome;
  • motility;
  • pathophysiology;
  • subtypes;
  • visceroperception

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

Abstract  Irritable bowel syndrome (IBS) consists of various subtypes. It is not known whether these subtypes share a common pathophysiology. Evaluation of motor and sensory function of the rectum using a barostat may help to explore a common pathophysiological background or differences in pathophysiology in subtypes of IBS. We have evaluated compliance, tone and sensitivity of the rectum, in both fasting state and postprandially, using a computerized barostat in 15 patients with diarrhoea-predominant IBS (IBS-D), 14 patients with constipation-predominant IBS (IBS-C) and compared the results with those obtained in 12 healthy controls. Rectal compliance as calculated over the steep part of the pressure–volume curve (17–23 mmHg) was decreased in both IBS groups (IBS-D 8.0 ± 1.4 mL mmHg−1; IBS-C 5.6 ± 1.1 mL mmHg−1) compared with controls (24.7 ± 3.5 mL mmHg−1). The perception of urge was increased only in IBS-D patients, whereas pain perception was significantly increased in both IBS groups. Spontaneous adaptive relaxation was decreased in IBS-D patients. Postprandially, rectal volume decreased significantly in the controls and in IBS-D patients, but not in IBS-C patients. In conclusion, both rectal motor and sensory characteristics are different between IBS-D and IBS-C patients. Therefore, testing of rectal visceroperception, adaptive relaxation and the rectal response to a meal may help distinguish groups of patients with different subtypes of irritable bowel syndrome.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

Irritable bowel syndrome (IBS) is frequently diagnosed.1,2 Because patients present with a variety of symptoms, such as abdominal pain, diarrhoea, obstipation and bloating, the syndrome has been subdivided into different subtypes, based on the predominant presenting symptom.3,4

Although subgroups of IBS patients can be easily distinguished based on complaints of patients, it is not known whether the subgroups share a common pathophysiology or whether differences exist in pathophysiology between subgroups of IBS.5,6

Before development of the barostat, studies in IBS focused on colorectal motility. However, results often lacked reproducibility, therefore the development of the barostat has greatly contributed to IBS research. Visceral hypersensitivity is now considered a hallmark of patients with IBS.7–10 Several studies have demonstrated that patients with IBS have lower thresholds for perception and increased sensations of discomfort during mechanical balloon distension both in the colon and rectum.7–10 Barostat or balloon distension studies in the rectum are easier to perform than in the colon. It is not known whether rectal compliance, tone and sensitivity as measured by barostat are different between patients with various subtypes of IBS.

Barostat studies in IBS patients are usually performed in the fasting state. However, bowel symptoms in IBS patients often emerge after eating.11 Therefore, differences in rectal motor and sensitivity characteristics between subgroups of IBS patient may become more prominent in the postprandial state.

We evaluated compliance, tone and sensitivity of the rectum by means of an electronic barostat in two groups of IBS patients: those with predominantly constipation and those with predominantly diarrhoea. In addition, healthy controls were studied. Our aim was to investigate whether differences exist in rectal compliance, tone and sensitivity between patients with constipation-type IBS and those with diarrhoea-type IBS.

Subjects and methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

Subjects

Twenty-nine patients with IBS according to the Rome II criteria for IBS11 were included. All patients were recruited from the outpatient clinic of the Department of Gastroenterology, which is a tertiary referral centre. Based on bowel frequency the group of patients was subdivided into two groups: patients with diarrhoea-predominant IBS (IBS-D; patients that had a bowel frequency of more than twice per day for 25% of the time) and patients with constipation predominant IBS (IBS-C; patients that had a bowel frequency of less than twice per week for 25% of the time). Patients who had previously undergone major abdominal surgical procedures were excluded. The IBS-D patient group consisted of nine women and six men, with a mean age of 49 ± 3 years (range 26–63 years). The duration since onset of symptoms was 9 ± 1 years. The IBS-C patient group consisted of eight women and six men, with a mean age of 41 ± 3 years (range 18–77 years; P = 0.68). The duration since onset of symptoms was 8 ± 2 years. Patients who met criteria for functional, slow transit or outlet-obstruction constipation were excluded. Apart from a disordered bowel frequency, all IBS patients suffered from severe abdominal pain, which was also a prominent complaint. All patients were instructed to stop any medication known to affect gastrointestinal function at least 3 days prior to study.

Twelve healthy volunteers, comprising seven women and five men, served as controls. None of the control subjects was on medication or had a relevant medical history. All subjects reported a normal bowel frequency and none had a history of constipation of diarrhoea. The mean age of the control subjects was 42 ± 4 years (range 19–64 years). All subjects gave informed consent and the study protocol was approved by the local human ethics committee.

Experimental protocol

An electronic barostat (visceral stimulator; Synectics Medical, Stockholm, Sweden) was used to perform the experiments. The maximum airflow of the device is 38 mL s−1. Further technical details of this distension device have been reported previously.12–14 At 08.00 h on the day of the experiment, subjects were allowed to eat a standardized breakfast, which consisted of a glass of orange juice, a cup of coffee or tea and two slices of toast with medium-fat margarine and marmalade (225 kcal; 2 g protein, 4 g fat and 40 g carbohydrates). Thereafter, subjects were only allowed to drink 150 mL water when thirsty. Subjects presented to our department at 01.00 h. The rectum was evacuated with an enema of 500 mL tap water. The study began 30 min later.

A polyethylene bag with a maximum capacity of 1000 mL was fixed to the end of a multilumen catheter (19 Fr). With the subject in the left lateral position, the lubricated and tightly folded polyethylene bag was introduced through the anus and positioned in the rectal ampulla. To unfold the bag, 200 mL air was manually inflated under controlled pressure (< 20 mmHg) and the catheter was pulled back carefully until its passage was restricted by the external anal sphincter. The tube was then introduced a further 2 cm, the bag deflated and the catheter connected to the barostat. During the experiment, subjects were in a prone 10° Trendelenburg position to reduce the gravitational effects of the abdominal organs. The experiment consisted of the following procedures.

Low volume isobaric ramp distension  During this procedure, the operating pressure was determined. The operating pressure was defined as the first pressure level that provided an intrarectal bag volume continuously above 80 mL (p80) and was determined by means of an isobaric distension procedure from 5 to 30 mmHg with steps of 1 mmHg per min. After reaching p80, the balloon was immediately deflated and subjects were allowed a 5-min rest period while the intrarectal bag remained deflated.

Double random staircase intermittent isobaric distensions  During this procedure, rectal compliance and visceroperception were determined. Both rectal compliance and visceroperception may influence the time-span between stools as well as the urgency and pain as experienced by IBS patients. The bag was distended intermittently every 60 s with steps varying between 7 and 33 mmHg at 2 mmHg intervals. Each step lasted 30 s followed by a 30-s rest period at 0 mmHg. Each step was repeated once, in a random order, thus providing a ‘double random staircase’ distension sequence. The procedure was stopped immediately when urge or pain became intolerable to subjects. In order to avoid patients dropping out right at the beginning of the procedure, the steps were clustered in three groups starting with the lowest pressures. The clusters ranged from 7 to 15 mmHg, 17–25 mmHg and 27–33 mmHg. Intra-bag pressures are presented as absolute pressures, not relative to operating pressure. During this procedure, rectal volume was continuously monitored. During the experiment, perception of the urge to defecate and abdominal pain were quantified using 100-mm visual analogue scales (VAS).15,16 Questions asked were: how strong is your urge to defecate? (with end points on the scale ranging from very weak to very strong); do you experience lower abdominal pain? (no pain to worst pain imaginable). Perception by means of VAS was scored every pressure step 20 s after start of the distension. Total duration of this procedure was 28 min. After finishing this procedure, subjects were allowed a 15-min rest period.

Set pressure distension  During this procedure the rectal spontaneous adaptive relaxation and postprandial response were determined. Both parameters dynamically influence the rectal capacity, thus possibly influencing IBS-symptoms. Adaptive relaxation is the active relaxation of the rectal wall in response to set pressure distension. The barostat was set to maintain a pressure equal to operating pressure (defined above). During the first 30 min (from t = −30 to t = 0 min), rectal volume was allowed to adapt to the set pressure. This volume adaptation is called spontaneous adaptive relaxation. At t = 0 min the volume has reached a steady state. At t = 0 min subjects drank a 400-mL homogenized semiliquid meal consisting of 100 g bananas, 80 mL whipped cream, 10 mL fruit syrup, 5 g Fantomalt (Nutricia, Zoetermeer, The Netherlands) and 150 mL water, which contained 3 g protein, 36 g carbohydrates and 35 g fat. The total caloric content of the meal was 580 kcal. After ingestion of the meal, postprandial rectal volume was recorded for another 60 min. Thereafter, the procedure was stopped (180–210 min total duration).

Data analysis

Barostat data were analysed using Polygram for Windows 2.04R (Medtronics, Denmark). Rectal volumes measured during the isobaric distensions are represented as the maximum volumes reached during each distension step. Of each pair of distensions with the same pressure, the mean volume was calculated. VAS scores were also averaged for each pair of distensions with the same pressure. Rectal compliance (mL mmHg−1 was approximated by calculating the difference in rectal volume divided by the difference in rectal pressure (ΔVP). This was performed for the steep part of the pressure–volume curve (17–23 mmHg) as well as for the part of the curve with a lesser slope (27–33 mmHg). Rectal wall tension was calculated during each pressure distension step by Laplace's law (T = p × r/2) and is expressed in mmHg cm−1. The radius of a spherical barostat bag can be calculated from the volume as follows:

  • image

The rectal wall tension therefore is:

  • image

where v = intrarectal bag volume, p = intrarectal bag pressure and r = radius.

Rectal volumes measured during the set pressure procedure are represented as average volumes over 5-min periods. Spontaneous adaptive relaxation was defined as the volume increase (mL, %) at the last 5-min period (from time t = 25 to t = 30 min) compared with the volume recorded during the first 5-min period (from time t = 0 to t = 5 min) as reference value. The postprandial response was defined as the relative change (mL, %) in rectal volume after 60 min compared the mean volume during t = −10 to t = 0 min.

Statistical analysis

Results are expressed as mean ± SEM. Statistical comparisons were made using the Mann–Whitney rank sum test, Student's t-test and anova with LSD correction for multiple comparisons, where appropriate. The relation between visceroperception parameters and wall tension was assessed by linear regression analysis. The fraction of variance of visceroperception parameters that are explained by changes in wall tension is presented as r2. Differences in the relation between visceroperception and wall tension are presented by estimates of the slope of the regression line. The significance of the regression model is given as the significance of F. The level of significance was set at P < 0.05.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

Isobaric distension

Figure 1 displays the pressure–volume curves from the isobaric distension procedure. Rectal compliance was significantly (P < 0.01) decreased in IBS patients as calculated over the steep part of the curve (17– 23 mmHg; IBS-D 8.0 ± 1.4 mL mmHg−1; IBS-C 5.6 ± 1.1 mL mmHg−1) compared with controls (24.7 ± 3.5 mL mmHg−1). Calculated over the part of the curve with a lesser slope (27–33 mmHg) no significant differences were observed between the groups (IBS-D 4.5 ± 1.7 mL mmHg−1; IBS-C 2.4 ± 1.7 mL mmHg−1; controls 7.1 ± 1.9 mL mmHg−1; P = 0.20).

image

Figure 1. Pressure–volume curve during intermittent isobaric distension (7–33 mmHg) of the rectum in IBS-D patients (●), IBS-C patients (+) and control subjects (▵). Rectal compliance was significantly reduced (P < 0.01) in IBS patients compared with control subjects.

Download figure to PowerPoint

Perception scores (VAS)

The threshold pressure for urge was 14.1 ± 2.1 mmHg in IBS-D patients, 18.8 ± 1.6 mmHg in IBS-C patients and 14.3 ± 1.9 mmHg in the controls (ns). Mean values for the urge to defecate during the isobaric distension are shown in Fig. 2. In all three groups a gradual and significant (P < 0.01) increase of the urge to defecate was observed during increasing pressure. However, the urge to defecate was reduced in the IBS-C patients compared with controls and IBS-D patients and the difference was significant (P < 0.05) at 23 and 25 mmHg.

image

Figure 2. Urge scores during intermittent pressure distension of the rectum in IBS-D patients (●), IBS-C patients (+) and control subjects (▵). At 23 and 25 mmHg the urge score of constipation-type IBS patients is decreased significantly (P < 0.05) compared with diarrhoea-type IBS patients and controls.

Download figure to PowerPoint

Mean values for pain during the isobaric distension are displayed in Fig. 3. In the control group, no significant increase in pain was observed, indicating that the stimulus was within the physiological range. A significant increase in pain over basal values was observed in both groups of IBS patients (P < 0.05 from P = 29 mmHg). Rectal distension at the highest pressures was not tolerated in six subjects. The procedure was stopped in four controls at pressures of 27, 29, 31 and 33 mmHg and two IBS-patients, both at 33 mmHg.

image

Figure 3. Pain scores during intermittent pressure distension of the rectum in IBS-D patients (●), IBS-C patients (+) and control subjects (▵). No significant differences were observed between the three groups.

Download figure to PowerPoint

Data of perception during rectal distension were also related to rectal wall tension, because wall tension takes both rectal pressure and volume into account. Regression analysis was performed to assess whether differences existed in urge and pain perception between both groups of IBS patients and controls. These results are shown in Table 1. IBS-D patients are characterized by an increased perception of both urge and pain and IBS-C patients are characterized by an increased perception of pain only.

Table 1.  Prediction of rectal visceroperception parameters by rectal wall tension
  R2*P-valueSlope of regression line 95% CI
  1. *The fraction of variance of visceroperception parameters that is explained by changes in wall tension. †Centimetre increase of VAS-score predicted per unit increase of wall tension (mmHg cm−1). P < 0.05 compared with controls and IBS-C patients. §P < 0.05 compared with controls.

Urge
 IBS-D0.78< 0.0010.0490.045–0.053
 IBS-C0.74< 0.0010.0320.030–0.036
 Controls0.78< 0.0010.0390.035–0.043
Pain
 IBS-D0.40< 0.0010.0170.014–0.020§
 IBS-C0.40< 0.0010.0230.019–0.027§
 Controls0.36< 0.0010.0110.008–0.014

Spontaneous adaptive relaxation

No difference in operating pressure was observed between IBS-D patients (17.8 ± 0.9 mmHg), IBS-C patients (17.5 ± 0.9 mmHg) and controls (16.4 ± 1.0 mmHg). Mean intrabag volume during this procedure is visualized in Fig. 4. Mean intrabag volume was significantly increased in the IBS-C patients compared with the IBS-D patients and controls throughout the first 15 min of the barostat procedure. A significant increase in intrabag volume was observed from time t = 10 to t = 30 min in both IBS patient groups and also in the controls. The degree of adaptive relaxation from time t = 5 to t = 30 min was significantly lower in IBS-D patients (41 ± 8 mL; 147 ± 17% of initial volume), compared with controls (81 ± 11 mL; 186 ± 15% of initial volume). The degree of adaptive relaxation was 70 ± 24 mL (170 ± 20% of initial volume) in IBS-C patients (ns compared with controls).

image

Figure 4. Volume of the barostat bag during the first 30 min after start of the barostat procedure, during set pressure. The amount of adaptive relaxation is significantly reduced (P < 0.05) in IBS-D patients (●), IBS-C patients (+) and control subjects (▵).

Download figure to PowerPoint

Postprandial response

After 30 min of basal volume recording, the semiliquid meal was consumed, followed by 60 min postprandial recording. Mean basal volume was significantly lower in IBS-D patients (174 ± 9 mL) compared with IBS-C patients (213 ± 23 mL) and controls (235 ± 19 mL; P < 0.01). Mean intrabag volume relative to basal volume (%) is shown in Fig. 5. Postprandially, a significant (P < 0.01) decrease of intrarectal bag volume was observed from time t = 45 to t = 60 min in the controls and in the IBS-D group. In IBS-C patients, no decrease in rectal volume was observed. Throughout this barostat procedure the VAS scores for urge were significantly increased in IBS-D patients (3.1 ± 0.8 cm) compared with IBS-C patients (0.9 ± 0.2 cm; P < 0.05). The mean postprandial VAS scores for pain were not significantly different (2.5 ± 0.8 and 1.2 ± 0.4, respectively; P = 0.17). Individual data of rectal tone characteristics (adaptive relaxation, response to a meal) were related to rectal sensitivity characteristics (urge and pain scores during maximal distension). Correlations were performed within subgroups of IBS-patients and in the group of IBS patients as a whole. No significant correlations were observed (Table 2).

image

Figure 5. Volume of the rectal barostat-bag relative to the volume at the time of the meal. A significant increase in rectal tone (P < 0.01) was observed both in IBS-D patients (●) and in controls (▵), but not in IBS-C patients (+). The difference in rectal response to a meal was significant between IBS-D patients and IBS-C patients from t = 55 min (P < 0.05).

Download figure to PowerPoint

Table 2.  Correlations between sensitivity scores (urge and pain) and rectal wall properties (compliance, adaptive relaxation, meal response)
 r (P-value)
 Compliance (17–23 mmHg)Compliance (27–33 mmHg)Percentage of adaptive relaxationPercentage of meal response
All IBS patients
 VAS urge at 33 mmHg−0.10 (0.59)−0.09 (0.65)−0.40 (0.07)0.07 (0.75)
 VAS pain at 33 mmHg0.04 (0.84)0.08 (0.67)0.10 (0.68)0.16 (0.46)
IBS-D patients
 VAS urge at 33 mmHg−0.28 (0.32)−0.31 (0.25)−0.45 (0.17)0.28 (0.32)
 VAS pain at 33 mmHg−0.27 (0.33)−0.02 (0.96)−0.06 (0.86)0.28 (0.31)
IBS-C patients
 VAS urge at 33 mmHg0.06 (0.84)0.15 (0.64)−0.32 (0.36)−0.27 (0.44)
 VAS pain at 33 mmHg0.52 (0.07)0.26 (0.39)0.22 (0.54)−0.15 (0.68)

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

We have demonstrated that both rectal motor and sensory characteristics are significantly different between patients with different subtypes of irritable bowel syndrome and healthy controls. Based on these characteristics, the groups of patients with IBS-D and IBS-C could be distinguished from healthy controls and from each other.

In the recent literature, attention has focused on disturbances of visceroperception rather than on gastrointestinal motor function as hallmark of IBS pathophysiology.4,7 Regarding diarrhoea- and pain-predominant IBS patients, increased visceroperception has been reported in several studies.7–10,17,18 However, results in constipation-predominant IBS patients are conflicting: both hyper-19 and hypo-sensitivity20 have been reported. Only a few studies have compared visceroperception in subgroups of IBS patients. In those studies, lowered perception threshold were observed only in IBS-D patients.5,6 Our study partially confirms these results: when related to wall tension, urge to defecate was only increased in IBS-D patients. However, compared with controls, pain perception was increased in both IBS patient groups.

The difference between urge and pain regarding the degree of variance in perception scores is notable. Whereas about 75% of the variance in urge scores can be explained from the variance in rectal wall tension, only 40% of the variance of pain scores is explained by the variance in rectal wall tension. This suggests that pain scores are much more biased by factors other than urge scores (e.g. psychological factors).

Apart from differences in visceroperception, significant differences in rectal tone and compliance were observed between subgroups of IBS patients and controls. Before development of the barostat, studies focused on colorectal motility using solid-state or water-perfused manometry assemblies. The main difference between manometry and the barostat is that the barostat is able to record changes in volume during pressure distension. If the pressure is kept constant, this change in volume can be interpreted as change in visceral tone. If the pressure is increased stepwise, compliance can be calculated from the pressure–volume curve. Manometry assemblies measuring visceral motility do not provide information on either tone or compliance. Rectal compliance as measured over the steep part of the pressure–volume curve was decreased in both groups of IBS patients. Compliance of the rectal wall is considered an important feature of rectal motor function. It determines the rectal capacity to store bowel contents delivered from the colon and is an important determinant of defecation frequency.5,19 There is a discrepancy in the literature regarding rectal compliance: both reduced19 and normal5 rectal compliance have been reported in IBS-C. In the present study, rectal compliance was evaluated by intermittent distensions, which may lead to results somewhat different from studies that use graded (ramp) pressure distensions. Differences in rectal compliance have rarely been noted using graded pressure distensions. However, during rapid intermittent distensions the rectum may behave differently. It remains unclear whether the differences between IBS patients and controls result from a reduction in rectal compliance per se or whether the rectum in IBS patients produces reflex responses that reduce the measured compliance. When evaluating visceroperception, rapid intermittent distensions with randomly varying pressure steps are preferred, because anticipation of increasing pressure steps as in stepwise distension is avoided.21 Differences between IBS patients and healthy controls are more pronounced with rapid intermittent than with stepwise distensions.22

Differences were also observed in dynamic rectal motor characteristics: spontaneous adaptive relaxation and the rectal response to a meal. Reduced adaptive relaxation and increased responsiveness to meal stimulation leads to a reduced rectal capacity in IBS-D patients. In contrast, increased adaptive relaxation and decreased responsiveness to a meal leads to an increased rectal capacity IBS-C patients. This agrees with the clinical pattern of complaints in both subgroups of IBS patients.

In contrast to the study by Grotz et al.23 who described a postprandial increase in rectal tone of 65% in healthy controls, we did not observe a prominent postprandial increase in rectal tone. This discrepancy in results may be related to several factors. For instance, we believe that the preparation and rectal cleaning of the subjects plays an important role; Grotz et al. cleaned the rectum with a phosphate enema, while we used tap water.

Differences in visceroperception between IBS patient groups cannot be seen separately from differences in rectal motor characteristics. Increased perception of urge and pain are related to lower rectal capacity, which is demonstrated both during the intermittent distension procedure (when increased visceroperception was accompanied by decreased rectal compliance), and during the set pressure procedure (when increased visceroperception was accompanied by decreased postprandial tone).

Although we found significant differences between the groups of IBS patients and healthy controls, individual data show overlap. This implies that based on barostat characteristics, it is not possible to classify individual subjects as IBS-C or IBS-D patients. No significant correlations were observed between individual data of rectal tone characteristics and rectal sensitivity characteristics.

Conclusion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

To summarise, we conclude that IBS patients are characterized by decreased rectal compliance during rapid intermittent distension, and increased rectal perception of pain. Differences between IBS-D and IBS-C patients exist both in rectal motor characteristics and visceroperception. Compared with IBS-C patients, IBS-D patients are characterized by an increased rectal perception for urge, a decreased adaptive relaxation and an increased gastro-rectal response. Based on rectal barostat studies, it is possible distinguish groups of patients with different subtypes of IBS.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References
  • 1
    Longstreth GF, Wolde-Tsadik G. Irritable bowel-type symptoms in HMO examinees. Prevalence, demographics and clinical correlates. Dig Dis Sci 1993; 38: 15819.
  • 2
    Agreus L, Svärsudd K, Nyren O et al. Irritable bowel syndrome and dyspepsia in the general population: overlap and lack of stability over time. Gastroenterology 1995; 109: 67180.
  • 3
    Thompson WG, Longstreth GF, Drossman DA, Heaton KW, Irvine EJ, Müller-Lissner SA. Functional bowel disorders and functional abdominal pain. Gut 1999; 45 (Suppl. II): 437.
  • 4
    Drossman DA, Whitehead WE, Camilleri M. Irritable bowel syndrome. A technical review for practical guideline development. Gastroenterology 1997; 112: 212037.
  • 5
    Prior A, Maxton DG, Whorwell PJ. Anorectal manometry in irritable bowel syndrome: differences between diarrhoea and constipation predominant subjects. Gut 1990; 31: 45862.
  • 6
    Simrén M, Abrahamsson H, Björnsson ES. An exaggerated sensory component of the gastrocolonic response in patients with irritable bowel syndrome. Gut 2001; 48: 207.DOI: 10.1136/gut.48.1.20
  • 7
    Mertz H, Naliboff B, Munakata J, Niazi N, Mayer EA. Altered rectal perception is a biological marker of patients with irritable bowel syndrome. Gastroenterology 1995; 109: 4052.
  • 8
    Ritchie J. Pain from distension of the pelvic colon by inflating a balloon in the irritable colon syndrome. Gut 1973; 14: 12532.
  • 9
    Whitehead WE, Holtkotter B, Enck P et al. Tolerance for rectosigmoid distention in irritable bowel syndrome. Gastroenterology 1990; 98: 118792.
  • 10
    Lembo T, Naliboff B, Munakata J et al. Symptoms and visceral perception in patients with pain-predominant irritable bowel syndrome. Am J Gastroenterol 1999; 94: 13206.
    Direct Link:
  • 11
    Talley NJ. Irritable bowel syndrome: disease definition and symptom description. Eur J Surg Suppl 1998; 583: 248.
  • 12
    Azpiroz F, Malagelada JR. Gastric tone measured by an electronic barostat in health and surgical gastroparesis. Gastroenterology 1987; 92: 93443.
  • 13
    Moragas G, Azpiroz F, Pavia J, Malagelada JR. Relations among intragastric pressure, postcibal perception, and gastric emptying. Am J Physiol 1993; 264: G11127.
  • 14
    Notivol R, Coffin B, Azpiroz F, Mearin F, Serra J, Malagelada JR. Gastric tone determines the sensitivity of the stomach to distention. Gastroenterology 1995; 108: 3306.
  • 15
    Blundell JE, Burley VJ. Satiation satiety and the action of fibre on food intake. Int J Obes 1987; 11 (Suppl. 1): 925.
  • 16
    Silverstone T. Measurement of hunger and food intake in man. In: SilverstoneB, ed. Drugs and Appetite. London: London Academic Press, 1982: 8192.
  • 17
    Prior A, Colgan SM, Whorwell PJ. Changes in rectal sensitivity after hypnotherapy in patients with irritable bowel syndrome. Gut 1990; 31: 8968.
  • 18
    Bradette M, Delvaux M, Staumont G, Fioramonti J, Bueno L, Frexinos J. Evaluation of colonic sensory thresholds in IBS patients using a barostat. Dig Dis Sci 1994; 39: 44957.
  • 19
    Slater BJ, Plusa SM, Smith AN, Varma JS. Rectal hypersensitivity in the irritable bowel syndrome. Int J Colorectal Dis 1997; 12: 2932.
  • 20
    Harraf F, Schmulson M, Saba L et al. Subtypes of constipation predominant irritable bowel syndrome based on rectal perception. Gut 1998; 43: 38894.
  • 21
    Whitehead WE, Delvaux M. Standardization of barostat procedures for testing smooth muscle tone and sensory thresholds in the gastrointestinal tract. Dig Dis Sci 1997; 42: 22341.
  • 22
    Lembo T, Munakata J, Mertz H et al. Evidence for the hypersensitivity of lumbar splanchnic afferents in irritable bowel syndrome. Gastroenterology 1994; 107: 168696.
  • 23
    Grotz RL, Pemberton JH, Levin KE, Bell AM, Hanson RB. Rectal wall contractility in healthy subjects and in patients with chronic severe constipation. Ann Surg 1993; 218: 7618.