Cerebral potentials evoked by esophageal distension in human

Recent studies have shown that cerebral evoked potentials (EPs) can be recorded after balloon distension of the human esophagus. The aim of this study was to evaluate the characteristics of these viscerosensory EPs and to investigate the relations between these EPs and perception of esophageal distension. Nineteen healthy volunteers (22-60 yr old) were studied. A balloon positioned 5 cm above the lower esophageal sphincter was inflated 10 times each minute. EPs recorded from four midline scalp electrodes were averaged for 50 and 100 inflation cycles. A clearly defined triphasic (negative-positive-negative) EP was recorded in all subjects and from all four recording sites when a volume leading to definite sensation and rapid balloon inflation (170 ml/s) was used. The latencies of the peaks were 231 +/- 7 (N1), 303 +/- 7 (P1), and 379 +/- 8 ms (N2). No significant correlation between stimulus perception and latency was found. The amplitude and quality of the EPs (scored by 3 blinded observers) increased significantly (P less than 0.01, ANOVA) with increasing sensation. Slow balloon inflation (30 ml/s) was significantly less effective in evoking EPs than rapid inflation (P less than 0.01). The EPs evoked by 100 inflations were not significantly clearer than those evoked by 50 inflations. It is concluded that the ability to record cerebral potentials evoked by esophageal balloon distension is related to the rate of balloon inflation and to the level of awareness of the stimulus.