RELATIONSHIP BETWEEN OLFACTORY FUNCTION, TRIGEMINAL SYSTEM AND NASAL ANATOMY IN NORMOSMIC SUBJECTS

Introduction: Few studies investigated the correlations between chemosensory function (trigeminal and olfactory) and nasal volume in humans although nasal anatomy is crucial for the sense of smell. Aim of this study was to evaluate these correlations in normosmic subjects. Materials and Methods: Two hundred and fifty eight healthy volunteers (age range 21-61 years, mean age 29.3 years, SD: 9) were enrolled. Olfactory function was investigated for (the rose-like) phenylethylalcohol odor threshold (OT), odor discrimination (OD) and odor identification (OI) using the Sniffin’ Sticks test, while nasal structure was evaluated by acoustic rhinometry (AR); trigeminal sensitivity was assessed in terms of detection thresholds for the odorless carbon dioxide (CO2). Results: Our data confirmed gender differences in the minimum cross sectional area, distance and volume of the olfactory cleft. Moreover, there were negative correlations between odor threshold versus AR area in both nostrils and versus best minimum cross sectional (MCA) area. Instead, positive correlations were observed between TDI score and AR volume. No significant correlations were found between OI versus nasal anatomy. As regards CO2, the trigeminal stimulus, positive correlations were detected between CO2 versus AR area in the right nostril and between CO2 versus best MCA area. Conclusion: The current results emphasize the significance of nasal anatomy for trigeminal/olfactory threshold perception. Interestingly, correlations are not found between suprathreshold odor identification and nasal anatomy. Further information is needed to instruct nasal surgery in terms of improvement of olfactory function.