Given the need for a clinical classification far daily patient examinations
to refer to each type of quantitative alteration in the sense of smell, we
have created a topographic classification of such alterations, establishin
g groups to distinguish among patients with decreased or total loss of olfa
ction. Because the classification is based on the diagnosis of the differen
t causes of anosmia, it implicitly includes etiologic and topographic consi
derations. We have established 3 main groups on the basis of the site of th
e causal lesion: conduction, sensorineural, and mixed anosmias. In addition
, within the sensorineural anosmias, we distinguish between the epithelial,
retroepithelial, and central anosmias.