A quantitative study of olfaction in multiple sclerosis

Background: Olfactory function in multiple sclerosis (MS) has not been extensively studied. Anecdotal cases describing disturbances in olfaction in MS have been reported; however, different investigations have yielded conflicting results. We performed a controlled study using a standardized quantitative test of olfactory function to determine the occurrence of microsmia in MS. Methods: The University of Pennsylvania Smell Identification Test (UPSIT) was administered to sixteen patients with clinically definite MS and fourteen age and sex-matched controls. Additionally, each patient and control was given a detailed questionnaire to ascertain subjective estimates of olfactory function. Patients and controls with concurrent conditions associated with microsmia or anosmia were excluded from the study. Results: In the patient group, mean expanded disability status scale (EDSS) was 5.2 (range 1.0 to 8.5) and mean disease duration was 12.3 years (3 to 50). One patient had subjective microsmia. Mean UPSIT scores were 32.1 +/- 8.1 in the patient group and 34.7 +/- 3.0 in the control group. This did not reach statistical significance (p = 0.66). Conclusion: On the basis of the UPSIT, patients with MS do not have significant impairment of olfactory function.