Olfactory Bulb Volume Changes in Patients with Sinonasal Polyposis: A Magnetic Resonance Imaging Study

Objectives. The olfactory bulb (OB) is thought to be a plastic structure with highly active afferent neurons. The aim of this study was to evaluate the effect of olfactory deprivation caused by sinonasal polyps on OB volume. Study Design. Cross-sectional study. Setting. Tertiary university hospital, Department of Otolaryngology. Subjects and Methods. Twenty-two subjects were included: 11 adult patients with bilateral allergic sinonasal polyposis (patient group) and 11 adult healthy controls (control group). Both study groups were matched for age and sex. OB volumes in all study subjects were evaluated in T2-weighted coronal MRI images by planimetric manual contouring. Results. In the patient group, OB volume measurements ranged from 5.2 to 19.5 mm(3) (mean +/- SD, 10.14 +/- 3.8). In the control group, volume measurements ranged from 35 to 75.8 mm(3) (mean +/- SD, 47.66 +/- 10.75). The difference in OB volumes between patient and control groups was statistically significant (P <.001). Conclusion. Our study highlights the significant reduction in OB volume in patients with bilateral sinonasal polyposis as compared with its volume in healthy controls. Further studies are required to evaluate the impact of OB volume reduction on olfactory recovery postoperatively.