Peripheral and central smell regions in patients with stroke: an MRI evaluation

We aimed to determine how odor pathways in the stroke were affected. Measurements were performed by magnetic resonance imaging (MRI).

Cranial MRI images of 82 adult patients were included. Group 1 was consisted of 41 patients with stroke. The control group (Group 2) was consisted of 41 patients without stroke. In both groups, peripheral (OB volume and olfactory sulcus (OS) depth) and central smell areas (insular gyrus area and corpus amygdala area) were measured by MRI.

Peripheral and central smell regions were smaller in the stroke group compared to the control group, whereas right and left side measurements were not different. There were positive correlations between measurements of the peripheral and central smell regions. In older patients with stroke, left OB volume and bilateral OS depths, bilateral insular gyrus areas and bilateral corpus amygdala areas decreased. As the duration of stroke increased, left OB volume decreased. In males with stroke, left OB volume was lower than the females with stroke. Linear regression analysis (backward) showed that in longer stroke duration, OB-volume_R increased and OB volume_L decreased. In older patients, corpus amygdala area_R decreased. In females, OB volume_L increased.

Both central and peripheral odor pathways were affected, and left OB in the peripheral odor pathways was even more affected in case of longer duration of the stroke. Changes in central and peripheral olfactory pathways in patients with stroke may not be aimed at neuroplasticity and repair, but rather may be a reflection of inflammation and degenerative changes in stroke.