Visceral pain perception in patients with irritable bowel syndrome and healthy volunteers is affected by the MRI scanner environment

Abstract

Background: The MRI scanner environment induces marked psychological effects, but specific effects on pain perception and processing are unknown and relevant to all brain imaging studies. Objectives and methods: We performed visceral and somatic quantitative sensory and pain testing and studied endogenous pain modulation by heterotopic stimulation outside and inside the functional MRI scanner in 11 healthy controls and 13 patients with irritable bowel syndrome. Results: Rectal pain intensity (VAS 0-100) during identical distension pressures increased from 39 (95% confidence interval: 35-42) outside the scanner to 53 (43-63) inside the scanner in irritable bowel syndrome, and from 42 (31-52) to 49 (39-58), respectively, in controls (ANOVA for scanner effect: p ¼ 0.006, group effect: p ¼ 0.92). The difference in rectal pain outside versus inside correlated significantly with stress (r ¼ À0.76, p ¼ 0.006), anxiety (r ¼ À0.68, p ¼ 0.02) and depression scores (r ¼ À0.67, p ¼ 0.02) in controls, but not in irritable bowel syndrome patients, who a priori had significantly higher stress and anxiety scores. ANOVA analysis showed trends for effect of the scanner environment and subject group on endogenous pain modulation (p ¼ 0.09 and p ¼ 0.1, respectively), but not on somatic pain (p > 0.3). Conclusion: The scanner environment significantly increased visceral, but not somatic, pain perception in irritable bowel syndrome patients and healthy controls in a protocol specifically aimed at investigating visceral pain. Psychological factors, including anxiety and stress, are the likely underlying causes, whereas classic endogenous pain modulation pathways activated by heterotopic stimulation play a lesser role. These results are highly relevant to a wide range of imaging applications and need to be taken into account in future pain research. Further controlled studies are indicated to clarify these findings.

Relationships of abdominal pain, reports to visceral and temperature pain sensitivity, conditioned pain modulation, and heart rate variability in irritable bowel syndrome

“…Visceral hypersensitivity to liquid ingestion can be the result of alterations in peripheral afferents, spinal cord transmission, exaggerated gastrocolonic reflex, altered central processing of afferent input and/or decreased descending inhibitory input. Other researchers have found reduced CPM efficiency in IBS‐D patients compared to HCs . However, we did not find this reduction.…”

Systematic review with meta‐analysis: conditioned pain modulation in patients with the irritable bowel syndrome

“…In this meta‐analysis, we excluded subgroups with concomitant pain conditions or psychological factors that may influence conditioned pain modulation; in Heymen et al, we excluded patients with migraine and temporomandibular joint disorders . We also excluded conditioned pain modulation measured inside the MRI machine in Wong et al Wilder‐Smith et al [2014] used two conditioned pain modulation paradigms; foot heat and capsaicin as test stimuli . However, enough data to calculate an effect size were only provided for capsaicin as test stimulus and foot heat stimulation as conditioning stimulus, and thus, only this paradigm was used in this meta‐analysis …”

The Increased Level of Depression and Anxiety in Irritable Bowel Syndrome Patients Compared with Healthy Controls: Systematic Review and Meta-analysis

“…[10][11][12][13][15][16][17][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] The baseline characteristics of included studies are shown in Table 1 22,29 Sphere score in 1 study, 24 and the Beck Anxiety Inventory (BAI) in 1 study. 30 …”

“…1,4,9 Animal studies have demonstrated the influence of stress on colonic permeability, and mucosal and systemic inflammation's mediation by the autonomic nervous system and the hypothalamo-pituitary-adrenal axis. 4 Several recently published studies have mapped IBS's relationship with psychological disorders [10][11][12][13][14][15][16] and compared depression and anxiety levels in IBS-subtypes. 15,17,18 However, the relationship between IBS and psychological disorders (depression or anxiety) was inconsistent, even in a recent meta-analysis entailing eight studies.…”