Identification and characterization of cerebral cortical response to esophageal mucosal acid exposure and distention

Background & Aims: Esophageal acid exposure is a common occurrence in healt hy individuals and patients with esophagitis. Clinically, perception of thi s exposure ranges from no perception to severe heartburn and chest pain. Ce rebral cortical response to esophageal mucosal contact to acid has not been systematically studied. The aim of this study was to elucidate cerebral co rtical response to esophageal acid exposure in normal individuals by functi onal magnetic resonance imaging (FMRI). Methods: We studied 10 normal healt hy volunteers. Cortical FMRI response to 10 minutes of intraesophageal perf usion of 0.1N HCl (1 mL/min) was determined, and the results were compared with those of saline infusion and balloon distention. Results: Acid perfusi on did not induce heartburn or chest pain but increased FMRI signal intensi ty by 6.7% +/- 2.0% over the preperfusion values. No increase was detected for saline infusion. FMRI signal intensity to balloon distention was simila r to that of acid perfusion; Activation latency, activation to peak, and th e deactivation periods for response to acid perfusion were significantly lo nger than those of balloon distention (P < 0.05). Conclusions: Contact of e sophageal mucosa with acid; before inducing heartburn, evokes a cerebral co rtical response detectable by FMRI. Temporal characteristics of this respon se are significantly different from those induced by esophageal balloon dis tention.