Infectious mononucleosis encephalitis. Possible therapeutic response to vidarabine.

A comatose patient with seizures and focal neurological signs was given vidarabine because herpes simplex encephalitis was a likely diagnosis. Investigations showed that the illness was due to infectious mononucleosis. Although recovery is usual in infectious mononucleosis encephalitis, the complete clinical and neuropsychological recovery documented in this severe case raises the possibility that vidarabine may have exerted a therapeutic effect.