Letter To the Editor

We read with interest the article by Oumerzouk et al. [1] about three patients with COVID-19 complicated by acute, disseminated encephalomyelitis (ADEM) [1]. Patient-1 was a 58yo male, with a 3d latency between onset of COVID-19 and onset of ADEM, who fully recovered on steroids [1]. Patient-2 was a 25yo male, with a 23d latency between onset of COVID-19 and onset of ADEM, who did 1d after starting steroids. Patient-3 was a 54yo female, with a 9d latency between onset of COVID and the onset of ADEM, who was being treated with steroids and had an incomplete recovery at the 3-month follow-up. The study is appealing but raises concerns that need to be discussed.

The diagnosis of ADEM remains unproven in all three patients. Cerebral lesions on MRI in patients with ADEM are usually hyperintense on T1, T2, FLAIR, and DWI and can enhance after administration of gadolinium [2]. However, only FLAIR images and only FLAIR and DWI images [1]. Not only one or two MRI modes should be shown of each patient, but also T1, T2, and even ADC and PWI images. Cerebral CT purports to show a hemorrhagic lesion in panel C [1]. However, the same CT scan also shows a right frontal lesion with “finger in glove enhancement” suggesting that the patient had received contrast medium for this investigation [1]. We should know how it was ruled out that the left parietal lesion shows contrast medium and not blood.

A right parietal lesion and a left thalamic lesion. However, the thalamus is not visible in any of the three images and the pretended right parietal lesion is not convincing. In addition, the quality of the three images is poor.

Caption of figure 6 describes “three hyperintense lesions in both frontal and left parietal regions surrounded by a hypointense corona, with signal voids interpreted as hematoma [1]. These lesions are not shown and it is unreported in which MRI modes these lesions were hyperintense. Blood on MRI is best documented on SWI sequences or on CT, which it is unclear whether they were performed. A further limitation is that spinal cord imaging was not performed. ADEM commonly affects the spinal cord and manifests as myelitis [3]. In order to confirm the diagnosis of ADEM, it is necessary to look not only for cerebral but also for spinal lesions. Furthermore, appropriate criteria should be applied to diagnostic to diagnose ADEM [4]. Hemorrhagic lesions in patient- 2 rather suggest acute, hemorrhagic, necrotising encephalitis (AHNE) than ADEM [5].

Overall, the interesting study has several limitations that call into question the results and their interpretation. ADEM should be evaluated using appropriate diagnostic criteria. Multimodal MRI is required to exclude differential diagnoses. Hemorrhagic lesions in patient-2 suggest AHNE rather than ADEM. 

Declarations

Funding Sources

No funding was received

Conflicts of Interest

None

Acknowledgement

None

Ethics Approval

Was in accordance with ethical guidelines. The study was approved by the institutional review board

Consent to Participate

Was obtained from the patient

Consent for Publication

Was obtained from the patient

Availability of Data

All data are available from the corresponding author

Code Availability

Not applicable

Author Contribution

JF: design, literature search, discussion, first draft, critical comments, final approval,

1. Oumerzouk, J. et al. “Clinicoradiological and prognostic features of covid-19-associated acute disseminated encephalomyelitis.” Revue Neurologique, vol. 178, nos. 1–2, 2022, pp. 144–50, doi:10.1016/j.neurol.2021.11.003.

2. Kawanaka, Y. et al. “Delayed appearance of transient hyperintensity foci on t1-weighted magnetic resonance imaging in acute disseminated encephalomyelitis.” Japanese Journal of Radiology, vol. 37, no. 4, 2019, pp. 277–82, doi:10.1007/s11604-018-00808-w.

3. Preziosa, P. et al. “Necrotic-hemorrhagic myelitis: A rare malignant variant of parainfectious acute disseminated encephalomyelitis in childhood.” Journal of the Neurological Sciences, vol. 384, 2018, pp. 58–60, doi:10.1016/j.jns.2017.11.032.

4. Cole, J. et al. “Acute Disseminated Encephalomyelitis in Children: An Updated Review Based on Current Diagnostic Criteria.” Pediatric Neurology, vol. 100, 2019, pp. 26–34, doi:10.1016/j.pediatrneurol.2019.06.017.

5. Ghosh, R. et al. “SARS-CoV-2-Associated Acute Hemorrhagic, Necrotizing Encephalitis (AHNE) Presenting with Cognitive Impairment in a 44-Year-Old Woman without Comorbidities: A Case Report.” The American Journal of Case Reports, vol. 21, 2020, e925641, doi:10.12659/AJCR.925641.