Anterior distribution of human olfactory epithelium

Objectives/Hypothesis: To functionally investigate the distribution of the olfactory epithelium in humans by means of the electro-olfactogram (EOG) an d anatomically located biopsy specimens. Study Design: Prospective, nonrand omized, investigational. Methods: Supra-threshold EOG recordings were made on 12 healthy, trained volunteers (6 women, 6 men; age range, 21-48 y), Van illin was used as the stimulus, since it exclusively excites olfactory rece ptor neurons. The EOG was recorded with tubular electrodes that were placed using thin-fiber endoscopic guidance. Biopsy specimens were obtained of an terosuperior nasal cavity mucosa in the same regions as the positive EOGs i n 15 smell-tested patients (7 women, 8 men; age range, 22-60 y) during rout ine nasal and sinus surgery. This biopsied tissue was histologically proces sed and stained for olfactory and neural proteins. Results: Viable response s to EOG testing were obtained in 7 of 12 subjects. In these seven subjects it was possible to identify nine sites above or below the anterior middle turbinate insertion where EOGs were obtained. The biopsy results showed mat ure olfactory receptor neurons in this same area. Conclusions: Human olfact ory epithelium appears to be distributed more anteriorly than previously as sumed.