Classification of acute encephalopathy in respiratory syncytial virus infection

Infection with respiratory syncytial virus (RSV) is known to be associated with central nervous system symptoms such as convulsions. We investigated cytokines, nitrogen oxide (NO)x, and the viral genome in cerebrospinal fluid (CSF) obtained from children with RSV infection-related convulsions or central nervous symptoms and compared the data with type of encephalopathy. Of nine patients enrolled (six boys and three girls; aged 10 days–3 years), one metabolic error, five excitotoxicity, one cytokine storm, and two hypoxia cases were found. The patients presented with unilateral convulsions, generalized convulsions, and convulsions following cardiopulmonary arrest, apnea, and nuchal rigidity. In all patients, a rapid check for RSV of nasal fluid was positive. The RSV genome (subgroup A) was detected in the CSF of five of the nine patients; two patients with hypoxic encephalopathy were negative for the RSV genome. The CSF interleukin (IL)-6 levels were high only in patients with the excitotoxicity and cytokine storm type of encephalopathy. NOx levels were high in all the subject cases. In the excitotoxicity type, NOx levels were significantly higher than those in the control and other groups. NOx level may become an important parameter for the diagnosis and classification of acute encephalopathy in RSV. Strategies to treat each type of encephalopathy, targeting cytokines and free radicals, should be established.