Olfactory Dysfunction in Multiple Sclerosis: Evidence of a Decrease in Different Aspects of Olfactory Function

Background/Aims: Numerous authors have described olfactory dysfunction in multiple sclerosis (MS) in recent years. The aim of this study was to specify the aspects of olfactory perception that are most affected and to identify any correlations with clinical, anatomical and functional data. Methods: 50 patients with remitting or secondary progressive MS were included. Personal data were collected (medical history, characteristics of their disease, depression and disability scores and number of lesions on cerebral imaging). An olfactory test (Sniffin Sticks®) was used to evaluate subjects’ olfactory function. Results: The odor detection threshold is the most sensitive marker, with 40% of patients presenting hyposmia. The ability to identify odors is affected later on, and is inversely correlated with the level of disability. Conclusion: Our results confirm that several aspects of olfactory function are altered in MS, particularly those aspects requiring greater cognitive involvement, such as discrimination and identification of odors.