ASSESSMENT OF THE VISCERAL AFFERENT AND AUTONOMIC PATHWAYS IN RESPONSE TO ESOPHAGEAL STIMULATION IN CONTROL SUBJECTS AND IN PATIENTS WITH DIABETES

Objective: To examine the effects of esophageal stimulation on vagal a fferent and efferent pathways in volunteers without diabetes and patie nts with diabetes. Design: Prospective physiological study. Participan ts: Fourteen control subjects without diabetes and 6 patients with dia betes. Interventions: Electrical and mechanical stimulation of the eso phagus. Outcome measures: Cortical evoked potentials and the power spe ctra of heart rate variability. Results: For the control subjects, the re was a significant decrease in the ratio of the low frequency to hig h frequency (LF:HF) power (i.e., increased vagal efferent modulation) during stimulation. Reproducible cortical evoked potentials were obtai ned from all control subjects. In the 6 patients with diabetes, who ha d viscerosensory and autonomic neuropathy, the cortical evoked potenti als showed an erratic non-reproducible response to electrical esophage al stimulation; however, the LF:HF ratio decreased in these patients d uring stimulation, suggesting an intact subcortical reflex circuit. Co nclusions: Vago-afferent fibres can be studied using minimally invasiv e techniques, and the power spectral analysis of heart rate variabilit y permits study of autonomic vago-efferent pathways.