Visceral sensitivity correlates with decreased regional gray matter volume in healthy volunteers: A voxel-based morphometry study

• Published in: Pain (Amsterdam) Vol. 155; no. 2; pp. 244 - 249
• Main Authors: Elsenbruch, Sigrid, Schmid, Julia, Kullmann, Jennifer S., Kattoor, Joswin, Theysohn, Nina, Forsting, Michael, Kotsis, Vassilios
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Elsevier B.V 01.02.2014; International Association for the Study of Pain; Elsevier
• Subjects: Adult; Biological and medical sciences; Cerebral Cortex - pathology; Cerebral Cortex - physiology; Cross-Sectional Studies; Female; Fundamental and applied biological sciences. Psychology; Gray matter volume; Healthy Volunteers; Humans; Interindividual differences; Magnetic Resonance Imaging - methods; Male; Organ Size; Pain Threshold - physiology; Rectal distension; Rectal pain threshold; Rectal sensory threshold; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Vertebrates: nervous system and sense organs; Visceral Pain - diagnosis; Visceral Pain - physiopathology; Visceral sensitivity; Voxel-based morphometry; Young Adult; Rectal distension; Rectal sensory threshold; Voxel-based morphometry; Gray matter volume; Rectal pain threshold; Interindividual differences; Visceral sensitivity; Healthy subject; Grey matter; Sensitivity; Pain; Interindividual comparison; Morphometry
• ISSN: 0304-3959; 1872-6623; 1872-6623
• DOI: 10.1016/j.pain.2013.09.027

Increased visceral sensitivity correlates with decreased gray matter volumes in pain-relevant brain regions in healthy volunteers. Regional changes in brain structure have been reported in patients with altered visceral sensitivity and chronic abdominal pain, such as in irritable bowel syndrome. It remains unknown whether structural brain changes are associated with visceral sensitivity. Therefore, we present the first study in healthy individuals to address whether interindividual variations in gray matter volume (GMV) in pain-relevant regions correlate with visceral sensitivity. In 92 healthy young adults (52 female), we assessed rectal sensory and pain thresholds and performed voxel-based morphometry (VBM) to compute linear regression models with visceral sensory and pain thresholds, respectively, as independent variable and GMV in a priori-defined regions of interest (ROIs) as dependent variable. All results were familywise error (FWE) corrected at a level of PFWE<.05 and covaried for age. The mean (±SEM) rectal thresholds were 14.78±0.46mm Hg for first sensation and 33.97±1.13mm Hg for pain, without evidence of sex differences. Lower rectal sensory threshold (ie, increased sensitivity) correlated significantly with reduced GMV in the thalamus, insula, posterior cingulate cortex, ventrolateral and orbitofrontal prefrontal cortices, amygdala, and basal ganglia (all PFWE<.05). Lower rectal pain threshold was associated with reduced GMV in the right thalamus (PFWE=.051). These are the first data supporting that increased visceral sensitivity correlates with decreased gray matter volume in pain-relevant brain regions. These findings support that alterations in brain morphology not only occur in clinical pain conditions but also occur according to normal interindividual variations in visceral sensitivity.