The Factors Associated With Olfactory Dysfunction in Patients with Multiple Sclerosis

Introduction An impaired sense of smell has a remarkable impact on the quality of life. It is seen in a variety of neurodegenerative diseases such as Parkinson disease. In this study, we assessed the olfactory function in patients with Multiple Sclerosis (MS) by Sniff Magnitude Test (SMT). Methods A cross-sectional study was conducted on 48 patients with MS. A questionnaire, including demographic and clinical variables, was completed for each patient. The SMT was used for the evaluation of olfactory function. Results Olfactory dysfunction was found in 14.6% of patients (8.3% hyposmia and 6.3% anosmia). Older age, longer disease duration, higher hospital admission rate, lower minimental status examination score, and secondary progressive course of MS were significantly related to olfactory dysfunction. Conclusion Secondary progressive MS and markers of advanced disease toward neurodegenerative phase (including older age, longer disease duration, and lower cognitive function) can be associated with olfactory dysfunction in MS patients.