Anterior cingulate cortex involvement in non-paraneoplastic limbic encephalitis.

Non-paraneoplastic limbic encephalitis is characterized by attention deficit, loss of emotion control, and impaired memory. Viral infection can cause acute encephalitis in children, occasionally exhibiting clinical features of limbic dysfunction. However, how viral infection affects the limbic system remains to be elucidated.A 5-year-old Japanese boy was admitted to our hospital because of high fever and status epilepticus. After seizures were controlled by diazepam, he exhibited attention deficit, loss of emotion control, and impaired memory, suggesting acute limbic encephalitis. Since titers of antibodies against Coxsackie virus A10 were significantly elevated in the serum, we diagnosed him with non-paraneoplastic limbic encephalitis associated with the viral infection. Brain magnetic resonance imaging demonstrated involvement of anterior cingulate cortex as well as white matter of the frontal lobe in the acute period. After steroid pulse therapy, these brain lesions subsequently disappeared in a time-dependent manner, beginning with the frontal lobe white matter and extending to the anterior cingulate cortex, and his psychological symptoms also disappeared.To the best of our knowledge, this is the first report to show the involvement of the region from the anterior cingulate cortex to the frontal lobe white matter. Clinical features such as seizures, attention deficit, loss of emotion control, and impaired memory suggest that this viral limbic encephalitis possibly extended from the frontal white matter to the anterior cingulate cortex via inter-neuronal connections in a time-dependent manner.