Abnormal visceral perception in patients with functional dyspepsia: use of cerebral potentials evoked by electrical stimulation of the oesophagus.

Abstract

Altered visceral perception is thought to be included in the pathogenesis of functional dyspepsia. However, in previous studies, the assessment of visceral perception has been based solely on patients self-reported symptoms. Cerebral evoked potential (EP), either by mechanical or electrical stimulation (ES) of the visceral organ, is used to evaluate visceral perception via afferent neural pathways. In this study, we investigated the visceral perception in patients with functional dyspepsia by EP to eliminate the possibility of self-reported bias. EP responses were recorded by oesophageal ES at 37 cm from the nostril in 14 patients with functional dyspepsia and 14 normal healthy control subjects. Threshold levels of perception, peak latencies and peak-to-peak amplitudes of EP were evaluated. There was no difference in the sensory threshold between the dyspeptic patients and the control subjects (median 6 mA, range 2-12 mA, vs. 8 mA, range 6-14 mA; P= 0.09). There was a strong trend towards a decreased discomfort threshold in the patients when compared to the control subjects (median 14 mA, range 6-24 mA vs. 20 mA, range 14-26 mA; P = 0.05). The latency of the later EP peak (N2) among the patients (154 ¿ 4 ms) was significantly shorter than that of the control subjects (171 ¿ 3 ms, P < 0.01) although there was no difference between the earlier peaks (Ni and P1). There was also no difference in the amplitudes (Ni/Pi and P1/N2) of EP between the patients and the control subjects. Half of the patients (seven out of 14) complained of nausea during ES but the control subjects were unaffected. The latency of the first EP peak (Ni) in the patients with nausea was significantly shorter (66 ¿ 3 ms) than that of the patients without nausea (79 ¿ 4 ms, P 0.05) or among the control subjects (80 ¿ 3 ms, P < 0.05). These results suggest that dyspeptic patients may recruit a greater number of fast conducting myelinated nerve fibres that convey visceral afferent impulses to the brain and/or that dyspeptic patients may have an altered central processing of the visceral perception. We conclude that EP recording by oesophageal ES provides an objective measurement of altered visceral perception in patients with functional dyspepsia.