Endogenous Inhibition of Somatic Pain Is Impaired in Girls With Irritable Bowel Syndrome Compared With Healthy Girls

Abstract

Endogenous pain-inhibition is often deficient in adults with chronic pain conditions including irritable bowel syndrome (IBS). It is unclear whether deficiencies in pain-inhibition are present in young children with IBS. The present study compared endogenous pain-inhibition, somatic pain threshold, and psychosocial distress in young girls with IBS versus controls. Girls with IBS did not show significant endogenous pain-inhibition of heat pain-threshold during a cold-pressor task in contrast to controls who had significant pain-inhibition. Girls with IBS did not differ from peers on measures of somatic pain but had more symptoms of depression, somatization, and anxiety than controls. When psychological variables were included as covariates the difference in paininhibition was no longer significant, although poor achieved power limits interpretation of these results. Higher-order cognitive processes including psychological variables may be contributing to observed pain-inhibition. In girls with IBS, pain-inhibition was positively related to the number of days without a bowel movement. To our knowledge, this is the first study to demonstrate deficiencies of endogenous pain-inhibition in young children with IBS. Findings have implications for better understanding of onset and maintenance of IBS and other chronic pain conditions.

Widespread Hyperalgesia in Adolescents With Symptoms of Irritable Bowel Syndrome: Results From a Large Population-Based Study

“…In a small sample of pre-menarchal girls, Williams, et al found no difference in heat pain threshold or in supra-threshold cold-pressor pain intensity, but evidence of impaired endogenous pain inhibition in IBS patients compared to healthy controls. 56 However, the latter result was not significant after controlling for psychological distress symptoms. As the authors note, this may be due to lack of statistical power.…”

“…Few studies have examined somatic pain sensitivity among children with chronically recurring abdominal pain, and only one including pediatric IBS patients. 1,17,18,56,60 Results from these studies have been equivocal, possibly due to the relatively small samples sizes. Furthermore, there are no prospective studies of pain sensitivity among children with recurrent abdominal pain and IBS, but increased somatic pain sensitivity was found in one study among adolescents and young adults with a history of childhood chronic abdominal pain.…”

(236) Impaired conditioned pain modulation in youth with functional abdominal pain

“…For this analyses, the assumption of homogeneity of regression slopes was met. Recent evidence of mean differences in CPM between girls with and without IBS (d = 0.71) suggests that a minimum of 53 adolescents per group would be necessary to detect CPM effects [52]. Based on evidence of individual differences in pain rating changes across conditioning trials during CPM procedures [29], we examined within-individual changes in pain ratings from the mean pre-conditioning rating across the three conditioning trials.…”

“…Normality assumptions were checked using a Q-Q plot of residuals. Exploratory analyses examined the distribution of CPM effects in FAP and healthy youth based on prior work suggesting significant variability in the strength and direction of these effects [52,56]. Three FAP youth were taking selective serotonin reuptake inhibitors at the time of their laboratory visit; removing them from analyses did not significantly alter any results.…”

“…Strikingly, 43% of FAP youth showed a pro-nociceptive pattern -or pain facilitating pain -reflected in mean pain rating increases from the pre-conditioning to conditioning phase. Previous studies have described this counterintuitive pattern of results as either "pain facilitation" [52] or "less efficient CPM" [56]; the mechanisms that contribute to CPM-related sensitization require greater elucidation. Variability in both the strength and direction of CPM effects coupled with evidence of within-person changes in test stimulus pain ratings during the 30-second hot water bath immersion support the use of multilevel modeling over mean pain ratings derived from multiple test stimuli administrations.…”