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

BACKGROUND AND PURPOSE: 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.

MATERIALS AND METHODS: 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.

RESULTS: 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 mm³ versus 44.87 ± 11.84 mm³, 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.

CONCLUSIONS: 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.