Systematic Reviews
Copyright ©The Author(s) 2025.
World J Methodol. Dec 20, 2025; 15(4): 99785
Published online Dec 20, 2025. doi: 10.5662/wjm.v15.i4.99785
Table 1 Basic characteristics and imaging results among patients with irritable bowel syndrome, mean ± SD
Ref.
Country
Study design
Sample size
Age/years
Females, %
Main result
Klinge et al[19], 2022DenmarkCase-control2025-5376%Low colonic volume and rapid transit time among IBS patients compared to chronic constipation
Lam et al[20], 2016United KingdomCase-control4827-5391.3%Higher ascending colon volume in functional constipation compared to IBS patients
Pritchard et al[21], 2014United KingdomCase-control5039 ± 1358.7%Less ascending colon postprandial volume and high descending colon volume among IBS compared to healthy controls
Di Palma et al[28], 2011ItalyCase-control4031 ± 766.7%Rectal volume was smaller among IBS patients
Nilsson et al[34], 2015DenmarkCross-sectional25Not mentionedAll malesNo inter-individual and intra-individual variability in colonic volume MRI
Grinsvall et al[38], 2021SwedenCase-control35427.9 ± 9.9All femalesLow grey matter volume in the posterior insula and superior frontal gyrus with high grey matter volume and cortical thickness in the somatosensory cortex and subcortical regions
Blankstein et al[39], 2010CanadaCase-control2730.85 ± 8.9All femalesIncreased gray matter in hypothalamus among patients with IBS, and anterior midcingulate cortical thinning
Chua et al[40], 2017TaiwanCase-control6936.7 ± 7.7All femalesSupramarginal cortex, middle frontal cortex, and left cuneus showed cortical thinning in IBS patients with a negative correlation with the disease severity
Jiang et al[42], 2013United StatesCase-control26634.72 ± 11.1284.6%No difference in cortical thickness between IBS patients and control subjects. Cortical thickness decreases in the bilateral subgenual anterior cingulate cortex, and increases in the somatosensory and primary motor cortex among women with IBS
Mao et al[43], 2020ChinaCross-sectional68Not mentionedDiarrhhea predominant subjectsEnlarged caudate nucleus and thalamus, and altered hemispheric asymmetries among diarrhea-predominant IBS patients
Chen et al[44], 2011CanadaCross-sectional2620-54All femalesMean fractional anisotropy was observed in IBS patients in the fornix and external capsules
Zhao et al[45], 2018ChinaCase-control3077.5 ± 6.320%Gray matter volume is low in occipital and frontal lobes, limbic and hippocampus, and high in angular and temporal gyrus, and insula
Icenhour et al[50], 2017SwedenCase-control6132-36All femalesResting-state functional connectivity is reduced in the amygdala and insula in IBS patients
Guleria et al[51], 2017IndiaCase-control2030.5All malesHomeostatic emotions, autonomic responses to pain, and affective motivation differ in IBS patients compared to controls
Table 2 Risk of bias assessment of the included studies
Ref.
Selection bias
Comparability bias
Outcome
Total score
Klinge et al[19], 20223137
Lam et al[20], 20164239
Pritchard et al[21], 20143137
Di Palma et al[28], 20113227
Nilsson et al[34], 20153227
Grinsvall et al[38], 20214239
Blankstein et al[39], 20103238
Chua et al[40], 20173238
Jiang et al[42], 20133227
Mao et al[43], 20203238
Chen et al[44], 20113227
Zhao et al[45], 20183238
Icenhour et al[50], 20173238
Guleria et al[51], 20173227