Background: This is to introduce a new test "negative alliesthesia" for measuring satiation after bariatric surgery. It is a test that is well known by physiologists but has never been used clinically. It is based on the observation that repeated pleasant gustatory stimuli turn into unpleasantness in the process of satiation.
Methods: We measured the time it took for a repeatedly ingested sweet stimulus to become first unpleasant (negative alliesthesia) and then intolerable (satiety). At the same time, we measured the degree of pleasure aroused by the sweet stimulus (hedonic rating). The test was given to 9 patients before and 3 and 6 months after the duodenal switch procedure and in 10 morbidly obese patients, three times, 3 months apart.
Results: The test showed that negative alliesthesia and satiety were three times faster after surgery. The negative alliesthesia time decreased from 16.0 +/- 3.9 minutes to 5.7 +/- 1.4 minutes (P < 0.0004). The satiety time decreased from 26.7 +/- 5.0 minutes to 10.7 +/- 1.3 minutes (P <0.001). Finally, the hedonic rating for the sweet stimulus decreased from 78.8% +/- 15.7% to 49.9% +/- 13.0% at 3 months and 39.3% +/- 20.6% at 6 months after surgery, without, however, reaching statistical significance.
Conclusion: The duodenal switch modified negative alliesthesia. It is too soon to say what place this test may have in bariatric surgery, but its simplicity and ingenuity are attractive.