Olfactory testing in clinical practice

Numerous techniques are available in the clinic for the investigation of chemosensory function. Psychophysical testing using orthonasal and retronasal stimulation routes may help to distinguish anosmic from hyposmic patients. These psychophysical tests are most frequently used for odour identification and odour threshold. Chemosensory event-related potentials using olfactory and trigeminal stimulation have become part of the routine investigation of patients with olfactory loss in specialised smell and taste centres. The interpretation of results from psychophysical testing is frequently supported by the assessment of chemosensory event-related potentials. This review will discuss these methods, including how to perform them, focusing on normative data and describing some clinical examples from our centre (olfactory and trigeminal event-related potentials).