907 GERD Alters the Functional Brain Connectivity Models Associated with Acid Stimulation

Abstract

Previous fMRI studies have documented in healthy controls and GERD patients activation of sensory/motor (SM), prefrontal (PF), anterior (AC) and posterior (PC) cingulate and insula (I) brain regions associated with esophageal acid perfusion. GERD was found to significantly amplify the volume and intensity of fMRI signals compared to controls. (Kern M, Am J Physiol 2004; 286(1):G174-81) The effects of GERD on the connectivity of cortical networks have not been studied. Aim: To compare the functional connectivity models of brain regions showing fMRI activation during esophageal acid perfusion in GERD patients and healthy controls. Methods: Structural Equation Modeling (SEM) was used to generate partial regression coefficients representing the covariance among regional fMRI signals activated by esophageal acid perfusion. We studied 7 GERD patients (4 female, age range: 20-62 years) and 8 controls (4 female, age range: 22-40 years), during high spatial resolution fMRI scanning sequences. Brain images were acquired during alternating intervals of 0.1N HCl and saline perfusion of the distal esophagus. Grouped data was used in the SEM to yield maps showing significant (p<0.05, goodness-of-fit test) connectivity paths from a general network based on known anatomical connections among the brain regions. Results: There were substantial differences in the connectivity maps associated with esophageal acid perfusion in GERD compared to controls. As seen (Figure), arrows between regions show the direction of significant covariance. Partial regression coefficients for these paths represent a measure of the degree of correlation between the regions. For all network models, GERD connectivity was different than that of the controls. These differences were characterized by decreased connectivity between limbic and para-limbic structures like the AC and I as well as altered patterns of connectivity between PF, I and AC in GERD compared to controls. Conclusions: Models of brain connectivity associated with esophageal acid perfusion differ when comparing patients and controls suggesting alteration of the cerebral cortical networks associated with processing visceral sensory input in GERD.