Neurogastroenterology Unit, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Department of Medicine, University Medical Cluster, National University Health System, Singapore.
Translational Research Centre for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium.
United European Gastroenterol J. 2016 Feb;4(1):132-41. doi: 10.1177/2050640615580888. Epub 2015 Apr 9.
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.
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.
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 = 0.006, group effect: p = 0.92). The difference in rectal pain outside versus inside correlated significantly with stress (r = -0.76, p = 0.006), anxiety (r = -0.68, p = 0.02) and depression scores (r = -0.67, p = 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 = 0.09 and p = 0.1, respectively), but not on somatic pain (p > 0.3).
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.
磁共振成像（MRI）扫描仪环境会引起明显的心理效应，但具体对疼痛感知和处理的影响尚不清楚，这与所有脑成像研究都相关。
我们对 11 名健康对照者和 13 名肠易激综合征患者进行了内脏和躯体定量感觉和疼痛测试，并研究了在 MRI 扫描仪内外进行异位刺激对内源性疼痛调制的影响。
在肠易激综合征患者中，相同直肠扩张压力下的直肠疼痛强度（VAS0-100）从扫描仪外的 39（95%置信区间：35-42）增加到扫描仪内的 53（43-63），在健康对照者中则从 42（31-52）增加到 49（39-58）（扫描仪效应的 ANOVA 分析：p=0.006，组效应：p=0.92）。在健康对照者中，扫描仪外与扫描仪内的直肠疼痛差异与应激（r=-0.76，p=0.006）、焦虑（r=-0.68，p=0.02）和抑郁评分（r=-0.67，p=0.02）显著相关，但在肠易激综合征患者中无显著相关性，这些患者的应激和焦虑评分预先显著更高。ANOVA 分析显示，扫描仪环境和受试者组对内源性疼痛调制有影响的趋势（p=0.09 和 p=0.1，分别），但对躯体疼痛无影响（p>0.3）。
在专门用于研究内脏疼痛的方案中，MRI 扫描仪环境显著增加了肠易激综合征患者和健康对照者的内脏疼痛感知，但不会增加躯体疼痛感知。心理因素，包括焦虑和应激，可能是其潜在原因，而异位刺激激活的经典内源性疼痛调制途径则起次要作用。这些结果与广泛的成像应用密切相关，需要在未来的疼痛研究中加以考虑。进一步的对照研究表明需要阐明这些发现。
