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RESEARCH PRODUCT

Comparison of olfactory function in patients with seasonal and perennial allergic rhinitis

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Hyposmia is a common symptom in allergic rhinitis. However, little is known about differences in the olfactory function of patients with seasonal or perennial allergy. A prospective controlled study was performed on 28 patients with allergic rhinitis to grass pollen and on 47 patients with allergic rhinitis to mites. Sixty-six healthy volunteers served as a control. Olfactory function was evaluated by a modified Connecticut Chemosensory Clinical Research Center testing procedure for threshold, identification, and discrimination. The grass pollen-allergic patients were tested preseasonally and after 3 weeks of intraseasonal grass pollen exposure; the mite-allergic patients and the volunteers were tested once. In the mite allergics, olfactory threshold, identification, and discrimination tests were significantly worse than in the volunteers (all P0.0001). In the grass pollen allergics, the results in olfactory identification and discrimination tests were not different from the controls if tested out of the season (both P0.05). However, in threshold testing (P = 0.0139), the results were worse. Intraseasonally, the grass pollen allergics showed a significant decrease in threshold, identification (both P0.0001), and discrimination testing (P = 0.0029). If the intraseasonal pollen allergics were compared to the mite allergics, they showed better results in identification (P = 0.0087) and threshold (P0.0001) tests, but worse results in discrimination testing (P = 0.0002). Therefore, the different kind of allergen exposure seems to result in a different pattern of allergic olfactory dysfunction.