Respiratory syncytial virus-associated seizures in Korean children, 2011–2016

Cha, Teahyen; Choi, Young Jin; Oh, Jae-Won; Kim, Chang-Ryul; Park, Dong Woo; Seol, In Joon; Moon, Jin-Hwa

There are various RSV-associated neuroradiological findings. In most cases, brain MRI reveals no changes. However, the findings of brain edema on computed tomography and focal HSI on MRI (fluid attenuation inversion recovery and DWI) in CSF RSV-positive patients with seizures in another study suggest a pathogenic heterogeneity. 11) Furthermore, DWI abnormalities in the globus pallidus in the patient suggest ischemic changes. 5) In the study by Park et al., 16) the abnormal MRI findings for RSV-related encephalitis were rhombenmesencephalitis, limbic encephalitis, and acute disseminated encephalomyelitis, and diffusion abnormality on DWI was not found. In our encephalopathy case, the patient showed transient HSI on DWI on the first day of acute symptoms; this rapidly disappeared over 3 days. Our case suggests that cytotoxic edema is one of the pathogenic mechanisms underlying RSV-associated encephalopathy. Moreover, DWI can detect the early changes in encephalitis, and appropriate timing of MRI is important to reveal the dynamic changes. 27) In the very acute stage, restricted diffusion can be detected; in the subacute stage, diffusion restriction diminishes and the ADC value increases. 27) A good outcome is usually related with the absence of cytotoxic edema, because it implies cellular edema, which may result in cellular death. 27) However, the outcome of our patient was favorable; hence, cytotoxic edema of white matter in RSV-associated encephalopathy may not always be associated with poor outcome. Transient white matter cytotoxic edema is rare, and has been previously reported in a child with traumatic brain injury, whose DWI and ADC revealed restricted diffusion in the corpus callosum and peri-atrial white matter. 28, 29) The abundant N-methyl-D-aspartate-receptors in the corpus callosum may lead to intracellular calcium entry. 28) Increased Ca 2+ activates enzymes such as ATPase, phospholipase, protease, and endonucleases can lead to the cell injury and death. 30) The limitation of this study lies in not including the nonseizure RSV-associated neurological complications and the inability to test RSV from CSF. Considering the high incidence and morbidity of RSV infection in young children, more studies are needed in the future.