[Gustatory olfactory function test with the Güttich technique: an evaluation of the clinical value]

Testing of retronasal olfactory sensitivity is routinely performed in many ENT-departments in German speaking countries. One of the most popular tests relates to an anecdotal report by Güttich [1]. In this test, liquids are placed on the patient's tongue; the patient is then asked to describe the aroma. Assuming that anosmic patients should not use other descriptors than "sweet," "sour," "salty," and "bitter", this test design is frequently applied in disability compensation settings. Surprisingly though, so far there are no studies regarding the sensitivity or specificity of this test in terms of the differentiation between hyposmic and anosmic patients.

The present investigation was performed in 50 anosmics, 42 hyposmics, and 13 normosmics. The diagnosis "hyposmia" or "anosmia" was based on 1. the patients' history, 2. psychophysical tests using an established test of olfactory function, the "Sniffin' Sticks," and 3. the recording of olfactory evoked potentials.

We obtained the following major results: 1. In comparison to hyposmis and normosmics, anosmic patients had greater difficulty identifying the aromas. However, correct identification was not always possible for normosmics. 2. Regarding the differentiation between anosmic and hyposmic patients, the test's sensitivity was 86% with a specificity of 62%. This clearly limits routine clinical application of this test.

Retronasal testing appears to be an elegant and simple means in order to screen olfactory function. However, the presently investigated approach is limited with regard to the discrimination between anosmic and hyposmic patients.