Early diagnosis of herpes simplex encephalitis by MRI.

The mortality rate of herpes simplex encephalitis (HSE) may be reduced by antiviral therapy, but early administration of the drug and therefore early diagnosis are essential. In our experience with four cases, MRI is the most sensitive noninvasive test in early diagnosis of HSE due to its high sensitivity to inflammatory increased brain water content, and it is superior to CT in localizing the pathognomonic lesions of the limbic system.