By Robert S. Fisher, M.D., Ph.D.
Editor-in-Chief

In over half of cases of epilepsy, doctors are unable to determine the underlying cause. This can be a major frustration for both patients and doctors. A recent article in the journal Epilepsia (2008, volume 49, issue 11, page 1828) suggests that a common virus named human herpes virus 6B (HHV6B), may be behind a considerable number of cases of temporal lobe epilepsy. HHV6B tends to infect children within the first five years of life, producing fevers, diarrhea, and sometimes a red skin rash called roseola. In more severe cases, it can cause meningitis or encephalitis, respectively, an infection of the lining of the brain or of the brain itself. One study showed that about one-third of children experiencing their first febrile seizure had blood evidence of an acute HHV6B infection. It is possible that HHV6B lies dormant in temporal lobe brain tissue, producing a reaction leading to scarring of the temporal lobe and a tendency for seizures. Brain removed in operations to cure epilepsy has been found to contain HHV6B DNA. Patients with the MRI finding of temporal scarring (called mesial temporal sclerosis) showed HHV6B DNA in 15 of 24 patients. None of 14 patients who did not have mesial temporal sclerosis showed HHV6B DNA in their brain tissue.

Comment: Causes of epilepsy undoubtedly are many and varied. Clues are emerging that infections with viruses such as HHV6B might be behind a significant fraction of currently mysterious epilepsy cases. If this viral hypothesis is proven true, then we may be able to employ antiviral antibiotics to prevent or cure some types of epilepsy.