A cortical evoked potential study of afferents mediating human esophageal sensation

The aim of this study was to compare the characteristics of esophageal cort ical evoked potentials (CEP) following electrical and mechanical stimulatio n in healthy subjects to evaluate the afferents involved in mediating esoph ageal sensation. Similarities in morphology and interpeak latencies of the CEP to electrical and mechanical stimulation suggest that they are mediated via similar pathways. Conduction velocity of CEP to either electrical or m echanical stimulation was 7.9-8.6 m/s, suggesting mediation via thinly myel inated A delta-fibers. Amplitudes of CEP components to mechanical stimulati on were significantly smaller than to electrical stimulation at the same le vels of perception, implying that electrical stimulation activates a larger number of afferents. The latency delay of similar to 50 ms for each mechan ical CEP component compared with the corresponding electrical CEP component is consistent with the time delay for the mechanical stimulus to distend t he esophageal wall sufficiently to trigger the afferent volley. In conclusi on, because the mechanical and electrical stimulation intensities needed to obtain esophageal CEP are similar and clearly perceived, it is likely that both spinal and vagal pathways mediate esophageal CEP. Esophageal CEP to b oth modalities of stimulation are mediated by myelinated A delta-fibers and produce equally robust CEP responses. Both techniques may have important r oles in the assessment of esophageal sensory processing in health and disea se.