Encephalitis and cerebellar ataxia associated with Epstein-Barr virus infections.

ENCEPHALITIS and cerebellar ataxia are rare complications of infectious mononucleosis (IM). Until recently the demonstration of a raised titre of heterophil antibodies in a Paul-Bunnell test provided the best objective data for substantiating a diagnosis of IM. Unfortunately, this test may produce both false positive and false negative results and may remain positive for many months after the acute phase of the illness. Epstein-Barr virus (EBV) is a member of the herpes group of viruses and is the causal agent of IM. The development of specific serological tests has allowed a more precise determination of the temporal relationship between EBV infection and various complications. We report two teenage boys who had encephalitis and cerebellar ataxia associated with EBV infections.