T. Hummel et al., Retronasal olfactory function: Clinical use of the "Guttich"-test in the diagnostics of olfactory disorders, LARY RH OTO, 78(11), 1999, pp. 627-631
Background: Testing of retronasal olfactory sensitivity is routinely perfor
med in many ENT-departments in German speaking countries. One of the most p
opular tests relates to an anecdotal report by Guttich [1]. In this test, l
iquids are placed on the patient's tongue; the patient is then asked to des
cribe the aroma. Assuming that anosmic patients should not use other descri
ptors than ,,sweet,",,sour,",,salty," and ,,bitter", this test design is fr
equently applied in disability compensation settings. Surprisingly though,
so far there are no studies regarding the sensitivity OF specificity of thi
s test in terms of the differentiation between hyposmic and anosmic patient
s. Methods: The present investigation was performed in 50 anosmics, 42 hypo
smics, 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. Results: We obtained the following major resu
lts: 1. In comparison to hyposmis and normosmics, anosmic patients had grea
ter difficulty identifying the aromas. However, correct identification was
not always possible for normosmics. 2. Regarding the differentiation betwee
n anosmic and hyposmic patients, the test's sensitivity was 86% with a spec
ificity of 62%. This clearly limits routine clinical application of this te
st. Conclusions: Retronasal testing appears to be an elegant and simple mea
ns in order to screen olfactory function. However, the presently investigat
ed approach is limited with regard to the discrimination between anosmic an
d hyposmic patients.