Olfactory dysfunction in Parkinson-plus syndromes: A comparison among themselves and controls

Objective Smell dysfunction may be a feature of Parkinson-plus syndromes such as multiple system atrophy and progressive supranuclear palsy. This study assessed the smell function of patients with Parkinson-plus syndromes and compared them with each other and their controls. Materials and Methods Utilizing the University of Pennsylvania Smell Identification Test (UPSIT) kits, the authors studied the olfaction of 30 Parkinson-plus syndrome patients (14 with multiple system atrophy [MSA] and 16 with progressive supranuclear palsy [PSP]) and 30 age- and sex-matched healthy controls in both nostrils and assessed whether the duration of disease influences these scores. Results The mean total UPSIT score of MSA was 13.00 ± 3.96 (right) and 13.00 ± 3.68 (left), and that of PSP was 12.00 ± 5.07 (right) and 12.06 ± 5.04 (left), while it was 29.73 ± 3.23 (right) and 29.90 ± 3.45 (left), with significant P -values (<0.001) between patients and controls and non-significant P -values between MSA and PSP. Overall, MSA patients had a lower ability to identify menthol, motor oil, mint, banana, clove, coconut, onion, licorice, cinnamon, gasoline, strawberry, gingerbread, lilac, turpentine, peach, pineapple, lime, orange, watermelon, paint thinner, grass, smoke, lemon, soap, and rose, while PSP patients could not identify bubble gum, cherry, dill pickle, natural gas, and peanut in either nostril. However, disease duration did not affect the patient scores. Conclusion Contrary to popular belief, patients with PSP and MSA have significantly impaired olfaction compared to controls, but the differences between PSP and MSA may not be significant.