Peripheric and central smell regions in patients with chronic rhinosinusitis with nasal polyps: An MRI evaluation

Abstract

Abstract OBJECTIVE. We evaluated the effect of olfactory deficiency caused by sinonasal polyposis using a magnetic resonance imaging (MRI) evaluation. MATERIAL AND METHODS. In this retrospective study, 33 adult patients with bilateral chronic rhinosinusitis with nasal polyps (CRSwNP) (Group 1) and 30 healthy subjects without nasal polyps (Control, Group 2) were included. On coronal T2 weighted SPIR images of the MRI, the olfactory bulb (OB) volume and the olfactory sulcus (OS) depth were measured; the same action was performed on the axial T1 weighted images, for the corpus amygdala and insular gyrus areas. RESULTS. OB volume, insular gyrus and corpus amygdala areas of the CRSwNP group were significantly lower than those in the control group (p<0.05). In the CRSwNP group, there were positive correlations between OB volumes, OS depths, and insular gyrus areas and corpus amygdala areas bilaterally (p<0.05). In females, bilateral insular gyrus areas decreased compared to the males (p<0.05). When polyp duration got longer, the right corpus amygdala area decreased (p<0.05). In older patients with a CRSwNP, the left corpus amygdala area decreased (p<0.05). CONCLUSION. OB volume was found to be smaller in the CRSwNP group. We think that the OB volume has decreased primarily due to decreased transfer of odor particles (sensory input) related to nasal obstruction and inflammation in the presence of nasal polyps. After OB volume shrinkage, the insular gyrus and corpus amygdala areas shrink due to the decreased data transfer to the central odor system. In patients with nasal polyps, olfactory functions may improve after endoscopic sinus surgery.