Olfaction and Its Correlates in Allergic Rhinitis: A Case Control Study

Olfactory dysfunction is frequent in rhinological disease. It has been attributed to nasal obstruction leading to impairment of transport of odorants to the olfactory epithelium or to inflammation in the olfactory cleft. We assessed olfaction in allergic rhinitis and correlated the olfactory score with other variables; in order to elucidate the pathogenesis of olfactory impairment in allergic rhinitis. Forty patients of allergic rhinitis (skin prick test positive) and forty healthy controls were included. The groups were evaluated for olfactory score, nasal airflow, peripheral eosinophilia, and levels of IgE and IL-5 in nasal secretions. The combined olfactory score in the patients was lower than that in controls. The score was better in patients with a better nasal airflow, but no significant association was found between the two. The peripheral eosinophilia and IgE and IL-5 level in nasal secretions was significantly higher in patients but demonstrated no significant correlation with the olfactory score. Allergic rhinitis patients had a decreased olfactory score; which weakly correlated to the nasal airflow. Local IgE and IL-5 were elevated in allergic rhinitis but did not show a significant correlation with olfactory scores. Our study concludes that both factors exist in allergic rhinitis but which factor is significantly responsible for hyposmia is not clear.