Decreased frontal and orbital volumes and increased cerebellar volumes in patients with anosmia Of Unknown origin: A subtle connection?

Purpose: Neuroimaging studies have shown that anosmia is accompanied by a decreased olfactory bulb volume, yet little is known about alterations in cerebral and cerebellar lobule volumes. The purpose of this study was to investigate structural brain alterations in anosmic patients.Methods: Sixteen anosmic patients (mean age 42.62 +/- 16.57 years; 6 women and 10 men) and 16 healthy controls (mean age 43.37 +/- 18.98 years; 9 women and 7 men) were included in this retrospective study. All subjects who underwent magnetic resonance imaging scans were analyzed using VolBrain and voxel-based morphometry after olfactory testing.Results: Despite being statistically insignificant, analysis using VBM revealed greater gray matter (GM) and white matter in the anosmia group compared to the healthy subjects. However, decreased GM (p < 0.001) and increased cerebellar (p = 0.046) volumes were observed in the anosmic patients.Conclusions: The study revealed structural brain alterations in specific areas beyond the olfactory bulb. Our re-sults indicate that the cerebellum may play an exceptional role in the olfactory process and that this will be worth evaluating with further dynamic neuroimaging studies.

Automated summary

Neuroimaging studies have found that anosmia is associated with a decrease in olfactory bulb volume, but little is known about changes in cerebral and cerebellar lobule volumes. This study aimed to explore the structural brain alterations in anosmic patients. The results showed that there were greater gray and white matter volumes in the anosmia group, although not statistically significant. However, decreased gray matter and increased cerebellar volumes were observed in the anosmic patients. These findings suggest the importance of further research on the role of the cerebellum in the olfactory process.