gms | German Medical Science

Introduction: Olfactory training has been shown to increase olfactory function in patients with olfactory loss. The present investigation aimed to study the question whether a change in olfactory function over time would be accompanied by a change in responsiveness of the olfactory epithelium as indicated by recordings of the electro-olfactogram (EOG), the summated generator potential of olfactory receptor neurons.

Methods: A total of 23 patients participated in two sessions, before and 4–6 months of olfactory training. During the “training” period patients were asked to sniff 4 odors every morning and evening. Olfactory function was assessed on both occasions using the Snffin‘ Sticks. EOG recordings were obtained under endoscopical control using tubular Ag-Ag-Cl-electrodes in response to stimulation with H2S and phenylethylalcohol (stimulus duration 1 s, interval > 1 min; olfactometer OM6b, Burghart, Germany). Trgeminal CO2-stimuli were used for control.

Results: Significant improvement of olfactory function was found in 8 or 23 patients. An increase in the number of EOG recordings was found not only in patients exhibiting an increase olfactory function as established by means of psychophysical tools, but across the entire group performing olfactory training. In contrast, responses to trigeminal stimuli did not change.

Conclusions: Systematic olfactory training improves olfactory function in approximately 1/3 of the patients over a period of 4–6 months. Olfactory training is associated with an increased responsiveness of the human olfactory epithelium to specific olfactory stimuli.

Support: DFG HU 441/18-1