Association of Olfactory Bulb Volume and Olfactory Sulcus Depth with Olfactory Function in Patients with Parkinson Disease

Abstract

Olfactory dysfunction is commonly associated with IPD. We here report the association of OB volume and OS depth with olfactory function in patients with PD. Morphometric analyses by using MR imaging and the Japanese T&T olfactometer threshold test were used to evaluate olfactory structure and function in 29 patients with PD and 29 age- and sex-matched healthy controls. The olfactory recognition thresholds were significantly higher in patients with PD than in healthy controls (3.82 ± 1.25 versus 0.45 ± 0.65, P<.001). Olfactory atrophy with reductions in the volume of the OB (37.30 ± 10.23 mm(3) versus 44.87 ± 11.84 mm(3), P<.05) and in the depth of OS (8.90 ± 1.42 mm versus 9.67 ± 1.24 mm, P<.05) was observed in patients with PD but not in controls. Positive correlations between olfactory performance and OB volumes were observed in both patients with PD (r=-0.45, P<.0001) and in controls (r=-0.42, P<.0001). In contrast, there was no significant correlation between the depth of OS and olfactory function in either cohort. The results provide evidence that early olfactory dysfunction in patients with PD may be a primary consequence of damage to the OB. Neuroimaging of olfactory structures together with the assessment of olfactory function may be used to identify patients with PD.