Radiological Response to the Call of the Pandemic:

Clinico-Neuroradiological Correlates of Acute Necrotizing Encephalopathy in COVID-19 Infection

by Ling Ling Chan^1,2, MBBS (S’pore), FRCR, FAMS
and Eng King Tan^2,3, MBBS (S’pore), MRCP, FAMS
¹Department of Diagnostic Radiology, Singapore General Hospital, Singapore
²Duke-NUS Medical School, Singapore
³Department of Neurology, National Neuroscience Institute – SGH Campus, Singapore

We read with interest the neuroimaging findings of the first presumptive case of encephalitis associated with COVID-19 infection in the Mar 2020 issue of Radiology by Dr Neo Poyiadji (1) and thank the authors for documenting and sharing their important findings with the community in the current pandemic.

We would like to highlight that medial temporal lobe involvement is unusual in the sporadic form of acute necrotizing encephalopathy (ANE), and rarely reported in acute necrotizing encephalopathy type 1, the familial form caused by mutations in the RANBP2 gene (2). Concentric lamellar rings of facilitated diffusion alternating with restricted diffusion have also been previously described in ANE (2). It would be interesting to know if such changes were also seen in this patient.

As patients infected with COVID-19 have been reported to present with anosmia, the olfactory nerve could serve as a plausible neuroinvasive route for coronaviral entry into the brain (3). Presence of high levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6 in the serum and cerebrospinal fluid (CSF) could support the widely accepted cytokine-induced neurotoxicity in ANE (2). As the first report of COVID-19 associated MR brain changes, it would also be useful to know the clinical outcome and follow up imaging of this patient given the absence CSF polymerase chain reaction confirmation of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in this patient.

Lastly, this report draws attention to the safety concerns of many Radiology practices (4,5) in imaging acute COVID-19 infection. In most centers, limited infrastructural support exists to cater to these high-risk isolation patients with COVID-19 infection e.g. negative air pressure MR scanner rooms to reduce risk of environmental contamination, meticulous segregation from non-COVID-19 patients and rigorous processes to disinfect the MR equipment. This is especially so in an escalation of the COVID infection when the primary priority is to ensure optimal cardiorespiratory support.

It cannot be over-emphasized that the risk-benefit of MR neuroimaging of each individual case needs to thoroughly discussed between the radiology and clinical teams so that appropriate imaging could be provided in the patient’s best interest (5).

References:

1. Poyiadji N, Shahin G, Noujaim D, Stone M, Patel S, Griffith B. COVID-19-associated Acute Hemorrhagic Necrotizing Encephalopathy: CT and MRI Features. Radiology. 2020 Mar 31:201187. doi: 10.1148/radiol.2020201187. [Epub ahead of print]
2. Wu X, Wu W, Pan W, Wu L, Liu K, Zhang HL. Acute necrotizing encephalopathy: an underrecognized clinicoradiologic disorder. Mediators Inflamm. 2015;2015:792578. doi: 10.1155/2015/792578. Epub 2015 Mar 22. Review.
3. Vaira LA, Salzano G, Deiana G, De Riu G. Anosmia and ageusia: common findings in COVID-19 patients. Laryngoscope. 2020 Apr 1. doi: 10.1002/lary.28692. [Epub ahead of print]
4. Cheng LT, Chan LP, Tan BH, Chen RC, Tay KH, Ling ML, Tan BS. Déjà Vu or Jamais Vu? How the Severe Acute Respiratory Syndrome Experience Influenced a Singapore Radiology Department's Response to the Coronavirus Disease (COVID-19) Epidemic. AJR Am J Roentgenol. 2020 Mar 4:1-5. doi: 10.2214/AJR.20.22927. [Epub ahead of print]
5. Mollura DJ, Palmore TN, Folio LR, Bluemke DA. Radiology preparedness in ebola virus disease: guidelines and challenges for disinfection of medical imaging equipment for the protection of staff and patients. Radiology. 2015 May;275(2):538-44. doi: 10.1148/radiol.15142670. Epub 2015 Feb 5.

Ling Ling Chan, MBBS (S’pore), FRCR, FAMS
Department of Diagnostic Radiology, Singapore General Hospital, Singapore; Duke-NUS Medical School, Singapore
Email: [email protected]