Electro-olfactogram (EOG) in olfactometry

Abstract

The electro-olfactogram (EOG) is a potential originated in olfactory epithelium evoked by odorous stimulation, which has been demonstrated and termed by Ottoson (1959). In order to ascertain the clinical application of EOG, we attempted to record similar potentials in human subjects. In some preliminary experiments using rabbits, it was quite easy to produce Ottoson's findings. In human subjects, however, there were sometimes great technical difficulties owing to the hidden anatomical position of the olfactory epithelium. Then we utilized Olympus selfoscope endoscopy for placing and retaining the electrode to the olfactory portion precisely and safely, with a tube for sending airborne odor. As results, we succeeded in recording negative spike discharge similar to Ottoson's findings. We examined a total of 27 nasal cavities in 22 patients with peripheral olfactory disorders and 11 nasal cavities in 12 patients with central olfactory disorders. The positive EOG rate in patients with peripheral or central olfactory disorders was 28 and 69%, respectively. Moreover, the positive rate was decreased in proportion to the degree of olfactory disorders in chronic rhinosinusitis. No positive EOG was observed in anosmic nasal cavities, while it was 68% in normal persons and resulted in an equal value to anosmia group caused by the damage of central olfactory pathway. From these results, it is considered that the positive EOG study is the only method which provides objective finding for the differential diagnosis of anosmia caused by disorders of olfactory epithelium or disorders of central olfactory tract.