Central response to painful electrical esophageal stimulation in well-defined patients suffering from functional chest pain

Background: Functional chest pain (FCP) of presumed esophageal origin is considered a common cause for chest pain in which central nervous system hyperexcitability is thought to play an important role. We aimed to compare cerebral responses with painful esophageal stimuli between FCP patients and healthy subjects (HS).

Methods: Thirteen patients with FCP (seven females, mean age 50.4 ± 7.5 years) and 15 HS (eight females, mean age 49.1 ± 12.9 years) were enrolled. Inclusion criteria consisted of typical chest pain, normal coronary angiogram, and normal upper gastrointestinal evaluation. Electrical stimulations evoking the pain threshold were applied in the distal esophagus, while cortical evoked potentials were recorded from the scalp. Pain scores, resting electroencephalogram (EEG), evoked potential characteristics and brain electrical sources to pain stimulation were compared between groups.

Key results: No differences were seen between patients and HS regarding (i) pain thresholds (patients: 20.1 ± 7.4 mA vs HS: 22.4 ± 8.3 mA, all P > 0.05), (ii) resting-EEG (P > 0.05), (iii) evoked brain potential latencies (N2: patients 181.7 ± 25.7 mS vs HS 182.2 ± 25.8 mS, all P > 0.05) and amplitudes (N2P2: patients 8.2 ± 7.2 μV vs HS: 10.1 ± 3.4 μV, all P > 0.05), (iv) topography (P > 0.05), and (v) brain source location (P > 0.05).

Conclusions & inferences: No differences in activation of brain areas to painful esophageal stimulation were seen in this group of well characterized patients with FCP compared with sex- and age-matched HS. The mechanism of pain in FCP and whether it originates in the esophagus remains unsolved.