Brain metabolism and persistent olfactory deficits after SARS-CoV-2 infection: An FDG-PET study

ABSTRACT

Background and aims: Coronavirus disease 2019 (COVID-19) due to SARS-CoV-2 infection has been associated with a number of neurological complications, including persistent hyposmia. Despite its relative frequency the neural bases of hyposmia post-SARS-Cov2 infection are to date poorly understood. Methods: 22 patients (12 males and 10 females;mean age 64±10.5 years, range 35-79) underwent whole-body [18] F-FDG-PET including a dedicated brain acquisition following their recovery after SARS-CoV-2 infection. Patients that previously required mechanic ventilation or showed severe respiratory distress syndrome due to SARSCoV- 2 infection were excluded given the potential independent effect of these clinical scenarios on brain metabolism. Among the enrolled patients, presence of isolated persistent hyposmia, as assessed with the smell diskettes olfaction test, was shown in fourteen subjects. A voxelwise analysis was used to identify brain regions of relative hypomebolism in hyposmic patients compared to a group of 61 age- and sex-matched healthy controlsStructural connectivity of these regions was assessed with the BCB toolkit. Results: Relative hypometabolism was demonstrated in bilateral parahippocampal and fusiform gyri and in left insula in hyposmic patients with respect to controls. Structural connectivity maps showed the involvement of the bilateral longitudinal fasciculi. Conclusion: Here we provide the first evidence of cortical hypometabolism in patients with isolated persistent hyposmia after SARS-CoV-2 infection without an history of severe respiratory distress. [18]F-FDG-PET may play a role in the identification of long-term brain functional sequelae of COVID-19.