Clinical evaluation of olfaction

An odor identification test and an odor threshold test offered satisfactory quantitative information on olfactory function in patients with chemosensory complaints. The threshold test used various concentrations of butanol presented in an ascending sequence. On each trial, the participant had to choose between stimulus and blank (two-alternative forced-choice procedure). The identification test used common odorous items (e.g., baby powder and ground coffee) and pungent items (e.g., ammonia) to test trigeminal function. A list of odor names and use of corrective feedback during testing overcame word-finding difficulty in odor identification. Each test readily distinguished between patients and control subjects. At present, a score that reflects the combined outcome of the tests is used to indicate five categories of functioning: normal osmesis, mild hyposmia, moderate hyposmia, severe hyposmia, and anosmia.