Acid hypersensitivity in patients with eosinophilic oesophagitis

Objective. Painful symptoms are prevalent in patients with eosinophilic oesophagitis but experimental data are sparse. The aim of this study was to compare the pain response to experimental oesophageal stimulation in 14 patients with eosinophilic oesophagitis and 15 healthy volunteers. Material and methods. A multimodal probe was placed in the oesophagus. The participants were subjected to mechanical, thermal and electrical pain stimuli followed by perfusion with 0.1 M HCl. Pain scores, referred pain areas and evoked brain potentials to electrical stimulation of the oesophagus were recorded. Results. Patients tolerated significantly less acid perfused in the oesophagus (median 123 versus 200 ml; P = 0.02) and felt the burning sensation evoked by the acid earlier (median 2.0 versus 5.0 min; P = 0.01). Eight patients had coexisting gastro-oesophageal reflux disease. Six patients had pure eosinophilic oesophagitis, and this group felt the acid earlier than those with concomitant reflux or the healthy volunteers (median 0.8 versus 2.0 and 5.0 min; P = 0.03). There were no differences between patients and controls in the responses to mechanical or thermal stimulation (P > 0.4). Furthermore, no differences were found for the proxies of central nervous system sensitization (response to electrical stimulations, referred pain areas or evoked brain potentials; P > 0.1). Conclusions. Patients with eosinophilic oesophagitis are hypersensitive to acid perfused in the oesophagus, and pathophysiologic findings are likely confined to the peripheral tissue. Reflux from physiological acid may play a role in the symptoms of eosinophilic oesophagitis.