Inter-hemispheric Functional Connections Are More Vulnerable to Attack Than Structural Connection in Patients With Irritable Bowel Syndrome

Abstract

Background/AimsIrritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disease characterized by recurrent abdominal pain and bowel dysfunction. However, the majority of previous neuroimaging studies focus on brain structure and connections but seldom on the inter-hemispheric connectivity or structural asymmetry. This study uses multi-modal imaging to investigate the abnormal changes across the 2 cerebral hemispheres in patients with IBS. MethodsStructural MRI, resting-state functional MRI, and diffusion tensor imaging were acquired from 34 patients with IBS and 33 healthy controls. The voxel-mirrored homotopic connectivity, fractional anisotropy, fiber length, fiber number, and asymmetry index were calculated and assessed for group differences. In addition, we assessed their relevance for the severity of IBS. ResultsCompared with healthy controls, the inter-hemispheric functional connectivity of patients with IBS showed higher levels in bilateral superior occipital gyrus, middle occipital gyrus, precuneus, posterior cingulate gyrus, and angular gyrus, but lower in supplementary motor area. The statistical results showed no significant difference in inter-hemispheric anatomical connections and structural asymmetry, however negative correlations between inter-hemispheric connectivity and the severity of IBS were found in some regions with significant difference. ConclusionsThe functional connections between cerebral hemispheres were more susceptible to IBS than anatomical connections, and brain structure is relatively stable. Besides, the brain areas affected by IBS were concentrated in default mode network and sensorimotor network.

Altered Brain Functional Asymmetry in Patients With Major Depressive Disorder Related to Gastrointestinal Symptoms

“…The cortical thickness of primary somatosensory cortex was associated with pain intensity in female irritable bowel syndrome (IBS) patients ( Grinsvall et al, 2021 ). Previous studies have reported aberrant activity and function of sensorimotor network in functional GI disorders ( Mayer et al, 2009 ; Duan et al, 2021 ; Liu G. et al, 2021 ). Moreover, we observed that altered PAS scores in the right postcentral gyrus had inverse correlation to sleep disturbance in MDD, implying that FC of postcentral gyrus corresponded with sleep quality, which was consistent with previous studies ( Huang et al, 2012 ; Klumpp et al, 2018 ).…”

Altered Resting Brain Functions in Patients With Irritable Bowel Syndrome: A Systematic Review

“…This systematic review comprised 22 rs-fMRI studies aimed at characterizing brain function (Li et al, 2013(Li et al, , 2018Zeng et al, 2013;Ma et al, 2014Ma et al, , 2015Gui et al, 2015;Ke et al, 2015;Qi et al, 2015Qi et al, , 2016aWeng et al, 2016;Qin et al, 2017;Wang et al, 2017;Nan et al, 2019aNan et al, ,b, 2021Ao et al, 2021;Chen et al, 2021;Geng et al, 2021;Liu et al, 2021). These studies were conducted at a variety of research sites around China and contained a sample size of at least 10 participants.…”

“…The diagnostic criteria for IBS in the included studies were respectively ROME III (Longstreth et al, 2006) in 19 studies (Li et al, 2013(Li et al, , 2018Zeng et al, 2013;Ma et al, 2014Ma et al, , 2015Gui et al, 2015;Ke et al, 2015;Qi et al, 2015Qi et al, , 2016aWeng et al, 2016;Qin et al, 2017;Wang et al, 2017;Nan et al, 2019a,b;Ao et al, 2021;Chen et al, 2021), ROME IV (Drossman, 2016) in one study (Geng et al, 2021), and undefined criteria in one study (Nan et al, 2021). For IBS categories, five studies included IBS-Diarrhea (IBS-D) patients (Ke et al, 2015;Wang et al, 2017;Ao et al, 2021;Chen et al, 2021;Geng et al, 2021), and one study (Liu et al, 2021) included patients with different IBS categories, including IBS-constipation (IBS-C), IBS-mix (IBS-M) and IBS-D. Two studies by Li J's team explored IBS with or without depression versus HCs (Li et al, 2018. Table 1 summarized the study's characteristics.…”

“…Two reviewers (Y-YL and LY) independently evaluated the risk of bias through six items and eventually reached a consensus. Among all, 16 studies were low risk of bias (Gui et al, 2015;Ke et al, 2015;Ma et al, 2015;Qi et al, 2015Qi et al, , 2016aWeng et al, 2016;Qin et al, 2017;Li et al, 2018Nan et al, 2019a;Ao et al, 2021;Chen et al, 2021;Geng et al, 2021;Liu et al, 2021). Four studies reduced to medium risk of bias, for undetailed exclusion criteria (Li et al, 2013;Ma et al, 2014;Nan et al, 2021), or insufficient baseline (Wang et al, 2017).…”

“…Two studies (Qi et al, 2016b;Liu et al, 2021) found increased VMHC in the cuneus, occipital, and posterior cingulate gyrus in patients with IBS, suggesting increased strength of inter-regional temporal correlations or functional connectivity between the cerebral hemispheres.…”