Introduction: The world has seen an uprise of olfactory disorders during the last years of COVID-19 pandemic, and unlike other infectious diseases, this was a more permanent alteration.

Objective: Assess olfactory bulb region through magnetic resonance imaging in individuals that persisted with olfactory disorder after COVID-19 infection.

Method: Retrospective observational study with patients with persistent olfactory disorder after COVID-19 infection (hyposmia/anosmia). Subjects underwent CCCRC olfactory testing, nasal endoscopy, and MRI. Study group was then compared to a control group, with individuals from 18 to 65 years, with no olfaction complain, and that were submitted to MRI before 2020 (pandemic period).

Results: Study group was of 59 adults, mean age of 44.9 (±7.4), with a slight superior number of women (64.7%). Control group has 42 individuals with mean age of 40.3 and with a slight male predominance (52.4%). In the control group, the olfactory bulb mean size was of 53.6mm3, ranging from 20.4mm3 to 139.7mm3. Study group had the following results: mean of 43.8mm3, ranging from 18.4mm3 to 90.8mm3, with p value of 0.0225.

Conclusion: These results suggest that COVID-19 infection can be related to alterations of olfactory bulb structure that can explain persistence of olfactory.

Keywords: Anosmia; Coronavirus; COVID-19; SARS-CoV-2; Olfactory bulb.