Patterns of olfactory dysfunctions in patients with Parkinson disease

Olfactory dysfunction (OD) is a well-established nonmotor manifestations (NMM) of Parkinson disease (PD) which needs objective assessment for better understanding of the disease pathogenesis. The aim of this work was quantitative and qualitative assessment of olfactory performance in newly diagnosed PD patients. This study was performed on 32 recently diagnosed PD patients and 24 healthy controls subjects (HCS) submitted to unified Parkinson’s disease rating scale–III (UPDRS–III), extended n-butanol Sniffin’ Sticks test (SST) and olfactory bulbs volumetry (OBV). There were significant decreases in SST threshold, discrimination, identification, and TDI variables as well as OBV in PD patients compared to HCS. The olfactory performance was negatively correlated with disease duration but had no relation with PD severity as well as motor subtype. OD is highly prevalent during the early stages of PD which is both measurable and specific with identification and discrimination impairments to certain odors which makes smell performance testing an important step in PD patients’ evaluation.