Effects of octreotide on esophageal visceral perception and cerebral evoked potentials induced by balloon distension

Octreotide, a somatostatin analog, is antinociceptive and increases perception threshold in the rectum. The aim of this study was to determine whether octreotide alters esophageal sensory thresholds and cortical evoked potentials (CEPs) resulting from intraesophageal balloon distension.

Twelve healthy volunteers (six men and six women, median age 25 yr, range 21-60 yr) underwent a randomized, double-blind, placebo-controlled trial of octreotide 100 microg s.c. versus saline. A 30-mm balloon was inserted 5 cm above the lower esophageal sphincter without topical anesthesia. The balloon was inflated at a rate of 170 cc/s to a maximum of 30 cc in 2 cc steps. Both pressure and volume were recorded. Patients reported first sensation (S1) and maximally tolerated pain (S2). Two cycles were performed both preinjection and 40 min postinjection. Evoked potentials were recorded from Cz to linked ears over 50 balloon inflation cycles (volume = S2).

Threshold volume to first sensation (S1) was significantly increased after octreotide injection [median (interquartile range): 24 (14-26) cc vs 13 (9-21) cc, p < 0.02]. No significant alteration in volume causing pain (S2) was noted after octreotide injection [29 (25-30+) cc vs 22 (19-29) cc]. Neither were volumes causing either first sensation [18 (11-24) cc vs 13 (9-18) cc] or pain [27 (23-30) cc vs 23 (21-25) cc] significantly altered by placebo injection. Neither amplitude nor latency of any of the three peaks of the evoked potential recordings differed significantly between postplacebo and postoctreotide recordings.

Octreotide significantly increased esophageal perception thresholds to balloon distension. It did not alter pain thresholds, nor were cortical evoked potentials to painful stimulation altered in normal subjects.