Gap between odor perception threshold and identification threshold: Calculation based on a graph of the Biolfa® olfactory test

Objectives: To develop a graph of semi-quantitative Biolfa(R) olfactory test data and to assess a method of mathematical measurement of the gap between odor perception and identification thresholds. Patients and methods: The semi-quantitative Biolfa(R) olfaction test comprises eight smells, each diluted in four increasing concentrations. Perception and identification threshold data for 158 patients was displayed in a radar-like diagram. The gap between odor perception threshold and odor identification threshold was quantified as the area between the perception and identification threshold curves. Results: The gap calculated between odor perception and identification thresholds differentiated between etiologic origins of olfactory disorders. In cm(2), the gap ranged from 0 to 82.73 cm(2). Low values indicated a peripheral origin, and high values a central origin for olfactory disorders (p > 0.05). On the other hand, no olfactory profile specific to each of the main etiologies responsible for olfactory disorder was found to exist. Conclusion: This radar-like graphic display of semi-quantitative Biolfa(R) olfactory test data is a simple means of providing an overall view of the data. Studying the gap between perception and identification thresholds for smells is relevant for diagnosis of central olfactory disorders. (C) 2010 Elsevier Masson SAS. All rights reserved.