Published December 3, 2020 as 10.3174/ajnr.A6912 LETTERS appreciate the effort among your staff that must be required to enhancement of the olfactory bulbs. However, they do not appear Ikeep the articles in the American Journal of Neuroradiology cur- to be enlarged, and this feature differs from a report in Neurology, rent as we learn more about the potential for CNS involvement in which transient enlargement without particularly evident sig- with coronavirus disease 2019 (COVID-19) infections. nal change was illustrated in a patient with COVID-19 and anos- The article in the September 2020 issue, “Anosmia in COVID- mia, albeit measured on MR imaging that appears to be acquired 19 Associated with Injury to the Olfactory Bulbs Evident on MRI,” on different scanners or at least with different techniques. is certainly timely and of considerable interest because this symp- This discrepancy among early reports supports the commen- tom has been reported in many infected patients. In this article, tary in the same issue, “Level of Evidence during COVID-19 the authors report their experience with the imaging of 5 patients Pandemic: Making the Case for Case Series and Case Reports.” I whom they believe demonstrated abnormalities of the olfactory agree that rapid publication of case reports of imaging findings bulbs, though 1 of these 5 did not have anosmia. While their article with COVID-19 will, in time, benefit our patients, but in the mean- appears to support the suspicion of many that COVID-19 directly time, we need to be particularly critical about the quality of these involves the olfactory bulbs, I think we should be careful that we early reports and avoid reaching any conclusions until there is con- are not seeing only what we expect to see. In Fig 1, where the sistent and reliable evidence regarding CNS involvement from authors point to presumed hemorrhage (microbleeding) into the COVID-19 infection. left olfactory bulb, there is also high signal in both inferior rectus muscles and bilateral frontal lobes just lateral to the olfactory sulcus REFERENCES on the precontrast scan and in the inferior frontal lobes on the 1. Aragão MF, Leal MC, Filho OQ, et al. Anosmia in COVID-19 associ- postcontrast scan. Because it is most likely that these other areas of ated with injury to the olfactory bulbs evident on MRI. AJNR Am J symmetric high signal along brain-bone-air interfaces in the orbits Neuroradiol 2020;41:1703–06 CrossRef Medline and frontal fossa are susceptibility artifacts, one could argue that 2. Laurendon T, Radulesco T, Mugnier J, et al. Bilateral transient ol- the high signal that appears to be in the olfactory bulb is also arti- factory bulb edema during COVID-19-related anosmia. Neurology factual. In support of that contention, the left and right olfactory 2020;95:224–25 CrossRef Medline bulbs do not appear enlarged or asymmetric on the STIR scan, sur- 3. Ikuta I. Level of evidence during COVID-19 pandemic: making prising with presumed hemorrhage. the case for case series and case reports. AJNR Am J Neuroradiol It is entirely possible, however, that one or more of the other 2020;41;1646 CrossRef Medline cases in which only postcontrast imaging is provided have real A. Mamourian Department of Radiology Penn State Health Milton S. Hershey Medical Center, Indicates open access to non-subscribers at www.ajnr.org Penn State College of Medicine http://dx.doi.org/10.3174/ajnr.A6912 Hershey, Pennsylvania AJNR Am J Neuroradiol : 2020 www.ajnr.org 1 Copyright 2020 by American Society of Neuroradiology.
American Journal of Neuroradiology – American Journal of Neuroradiology
Published: Dec 3, 2020
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