Olfactory Function Evaluation

Methods of Olfactory Evaluation

The American Academy of Otolaryngology recommends using psychophysical methods, which include threshold and suprathreshold tests, to evaluate olfactory function 1, 2
Threshold tests detect the minimum concentration of an odorant that can be perceived by a subject, commonly using substances like phenylethylamine or n-butanol 2, 3
Suprathreshold tests include odor identification and discrimination tests, using concentrations much higher than the threshold 2, 3

The American Rhinologic Society suggests that patients with chronic rhinosinusitis (CRS) often present with olfactory impairment but may not be fully aware of their deficit 4
It is recommended to evaluate olfactory function both subjectively and objectively in patients with CRS 4
Olfactory tests can be useful during follow-up of patients with CRS, primarily to monitor the outcomes of anti-inflammatory or surgical treatment 4

The European Rhinologic Society recommends using standardized psychophysical tests with a sufficient number of odors to obtain significant results 1, 2
Short tests with fewer odors may reduce cost and time but introduce a degree of unreliability and should only be used for screening purposes 1, 2

Rigid nasal endoscopy can differentiate between possible causes of inflammatory olfactory loss 2, 3
If the subjective and psychophysical level of olfactory loss does not correlate with endoscopic findings, it may raise suspicion of a sinonasal or skull base tumor 2, 3
MRI or CT scans can exclude olfactory and pituitary tumors and aneurysms 2, 3