Pediatric acute disseminated encephalomyelitis following asymptomatic coronavirus disease 2019.

After the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic emerged, the virus spread rapidly worldwide, and outbreaks continued to occur intermittently. Here, we present the case of a 5-year-old boy with acute disseminated encephalomyelitis (ADEM) and initial symptoms of dysphoria and pain in the right lower extremity. Around the time of this episode, the patient exhibited no fever or respiratory symptoms. Brain magnetic resonance imaging (MRI) revealed multiple T2-weighted image/fluid-attenuated inversion recovery high-signal areas bilaterally subcortical to the deep white matter, corpus callosum, and bilateral basal ganglia. MRI of the cervical and thoracic regions indicated a long lesion with continuous T2WI high signal intensity in the central gray matter. Serum aquaporin-4 antibody and serum myelin oligodendrocyte glycoprotein antibody tests were negative and positive, respectively. A polymerase chain reaction test using nasopharyngeal swab fluid upon admission was positive for SARS-CoV-2. Patients with severe coronavirus disease 2019 (COVID-19) in the acute phase may show central nervous system symptoms. There have been no previous reports of ADEM in the subacute phase of COVID-19, lacking symptoms in the acute phase, as in the present case. Notably, ADEM can develop in the subacute phase of asymptomatic COVID-19 infection.