Smell Testing: Purpose, Procedure, Interpretation

Deterioration of the sense of smell can be either quantitative (a reduction in intensity) or qualitative (a change in quality or degree of distortion). To a greater extent than via history, olfactory testing can reveal quantitative impairment (such as distortion). Clinical olfactory testing presents a patient with an olfactory probe to his or her nose and records the individual’s reaction. This type of evaluation is sometimes called “psychophysical testing.” Patients undergoing olfactory testing should be cooperative, able to follow directions, and articulate their preferences. Odor identification and odor discrimination tests are examples of suprathreshold olfactory testing. Olfactory threshold tests fall into a similar category. Supranasal tests are more likely to evaluate the central processing of olfactory information. In contrast, odor threshold tests are more likely to evaluate the peripheral olfactory ability (such as the conductive and sensorineural function of the nose). Consequently, olfactory testing might consist of both odor threshold tests and suprathreshold tests. The olfactory epithelium may not receive odorants if a mass blocks the nasal cavity. Nasal polyps, inverted papilloma, and other nasal tumors are the most prevalent conditions. Infectious and inflammatory diseases exacerbate central abnormalities in olfaction and transmission.