CEREBRAL EVOKED-POTENTIALS - A METHOD OF QUANTIFICATION OF CENTRAL-NERVOUS-SYSTEM RESPONSE TO ESOPHAGEAL PAIN

Cerebral evoked potentials (EPs) represent a new technique for the eva luation of afferent outflow from the gastrointestinal tract. We compar ed EPs obtained with distension of the distal and proximal esophagus. Responses were recorded with the balloon 5 cm proximal to the lower es ophageal sphincter and 3 cm distal to the upper esophageal sphincter. Balloon stimulation resulted in cortical responses recorded by midline scalp electrodes (CZ', PZ, and OZ by the International 10-20 system) in normal volunteers. EP responses consisted of two negative (N1, N2) and one positive (P1) deflections. The proximal esophageal latency of N1 was shorter in all three leads. The latency to P1 was shorter with proximal stimulation in lead CZ' only, and N2 latencies were not diffe rent. Amplitudes expressed as the difference between N1 and P1, and P1 and N2 were not different. When two sets of potentials several minute s apart from the proximal position were compared, a decrease in amplit ude with the second set of stimulations was noted. Esophageal EP recor ding is a new technique that may provide information about the integri ty and function of the sensory innervation of the esophagus.