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. 2021 Mar 12;9(3):287.
doi: 10.3390/biomedicines9030287.

Brain Metabolic Correlates of Persistent Olfactory Dysfunction after SARS-Cov2 Infection

Maria Isabella Donegani  1   2 , Alberto Miceli  1   2 , Matteo Pardini  1   3 , Matteo Bauckneht  1   2 , Silvia Chiola  4   5 , Michele Pennone  1   2 , Cecilia Marini  1   6 , Federico Massa  1   3 , Stefano Raffa  1   4 , Giulia Ferrarazzo  1   4 , Dario Arnaldi  1   4 , Gianmario Sambuceti  1   4 , Flavio Nobili  1   3 , Silvia Morbelli  1   2
Affiliations

Brain Metabolic Correlates of Persistent Olfactory Dysfunction after SARS-Cov2 Infection

Maria Isabella Donegani et al. Biomedicines. .

Abstract

We aimed to evaluate the brain hypometabolic signature of persistent isolated olfactory dysfunction after SARS-CoV-2 infection. Twenty-two patients underwent whole-body [18F]-FDG PET, including a dedicated brain acquisition at our institution between May and December 2020 following their recovery after SARS-Cov2 infection. Fourteen of these patients presented isolated persistent hyposmia (smell diskettes olfaction test was used). A voxel-wise analysis (using Statistical Parametric Mapping software version 8 (SPM8)) was performed to identify brain regions of relative hypometabolism in patients with hyposmia with respect to controls. Structural connectivity of these regions was assessed (BCB toolkit). Relative hypometabolism was demonstrated in bilateral parahippocampal and fusiform gyri and in left insula in patients with respect to controls. Structural connectivity maps highlighted the involvement of bilateral longitudinal fasciculi. This study provides evidence of cortical hypometabolism in patients with isolated persistent hyposmia after SARS-Cov2 infection. [18F]-FDG PET may play a role in the identification of long-term brain functional sequelae of COVID-19.

Keywords: 18F-FDG PET; COVID-19; SARS-CoV-2; anosmia; olfactory dysfunction.

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Conflict of interest statement

Silvia Morbelli and Flavio Nobili have received speaker honoraria from G.E. Healthcare. All other authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flow-chart reporting steps that narrowed the final study group to fourteen patients still presenting with hyposmia during early recovery after SARS-CoV-2 infection. Pt, patients.
Figure 2
Figure 2
Hypometabolism with respect to controls in patients still presenting with hyposmia during early recovery after SARS-CoV-2 infection was highlighted in parahippocampal and fusiform gyri in both hemispheres (BA 20, 36, 37) and in the insula in the left hemisphere (BA 13). Height threshold of significance was set at p < 0.05 FWE-corrected at the cluster level. Regions of significant difference are shown color-graded in terms of Z values. Talairach coordinates and further details are available in Table 2.
Figure 3
Figure 3
Structural connectivity of regions of hypometabolism in patients with olfactory dysfunction generated through the Brain Connectivity and Behaviour (BCB) toolkit (http://www.toolkit.bcblab.com (accessed on 10 December 2020)), which includes diffusion MRI data from healthy control subjects. Panel (A): The connectome map indicated a significant probability of connection of the hyposmia cluster with the inferior longitudinal fasciculus; Panel (B): tractography results of the hyposmia cluster.
See this image and copyright information in PMC

References

    1. Ellul M.A., Benjamin L., Singh B., Lant S., Michael B.D., Easton A., Kneen R., Defres S., Sejvar J., Solomon T. Neurological associations of COVID-19. Lancet Neurol. 2020;19:767–783. doi: 10.1016/S1474-4422(20)30221-0. - DOI - PMC - PubMed
    1. Lechien J.R., Chiesa-Estomba C.M., De Siati D.R., Horoi M., Le Bon S.D., Rodriguez A., Dequanter D., Blecic S., El Afia F., Distinguin L., et al. Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): A multicenter European study. Eur. Arch. Otorhinolaryngol. 2020;277:2251–2261. doi: 10.1007/s00405-020-05965-1. - DOI - PMC - PubMed
    1. Saussez S., Lechien J.R., Hopkins C. Anosmia: An evolution of our understanding of its importance in COVID-19 and what questions remain to be answered. Eur. Arch. Otorhinolaryngol. 2020:1–5. doi: 10.1007/s00405-020-06285-0. - DOI - PMC - PubMed
    1. Fotuhi M., Mian A., Meysami S., Raji C.A. Neurobiology of COVID-19. J. Alzheimers. Dis. 2020;76:3–19. doi: 10.3233/JAD-200581. - DOI - PMC - PubMed
    1. Galougahi M.K., Ghorbani J., Bakhshayeshkaram M., Naeini A.S., Haseli S. Olfactory Bulb Magnetic Resonance Imaging in SARS-CoV-2-Induced Anosmia: The First Report. Acad Radiol. 2020;27:892–893. doi: 10.1016/j.acra.2020.04.002. - DOI - PMC - PubMed