Changes in olfactory bulb volume and olfactory sulcus depth in COVID-19 infection: an autopsy study

The pathophysiology of COVID-19 remains unclear. Olfactory dysfunction is one of the neurological symptoms of the disease. There is no evidence to evaluate whether there is a morphometric change in the olfactory pathways. This study aimed to examine the effect of COVID-19 on olfactory center sections through morphometric measurements obtained from autopsy cases.

Our study was conducted on 63 autopsy cases (COVID-19 [n = 37], control (non-COVID) [n = 26]) between the ages of 18-80 years who came to Tokat Forensic Medicine Institute. The anatomical structures of the olfactory tracts were determined on the brains removed during routine autopsy. The dimensions of the structures belonging to the olfactory center sections were measured with a precision digital caliper, weights were measured with a precision digital scale, and volumes were measured with a 0.01 cm³ graduated cylinder. The Archimedes principle method was used for volume calculations.

In the autopsy cases examined, it was found that there was a significant decrease in bilateral olfactory bulb (OB) and olfactory tract (OT) volumes in COVID-19 group (p < 0.001). In addition, OB and OT weights were lighter in COVID-19 group on both sides (p < 0.001). The length, width and depth measurements of the examined anatomical structures were found to be shorter in COVID-19 group (p < 0.01).

Autopsy findings showed damage in olfactory center sections in COVID-19 group. We believe that knowing the OB and OT morphology in particular will make significant contributions to both clinical approaches and future studies in the pathology of infectious diseases.