Encephalitis

Abstract

Encephalitis is defined as an inflammatory disease of the brain with neurologic dysfunction as a result of direct infection of the brain parenchyma, a post-infectious process, or non-infectious process (such as NMDA-receptor antagonism). Neurologic dysfunction may manifest as seizures, decreased level of consciousness, ataxia, or other focal neurologic dysfunction, and importantly is not due to another infectious process of the brain. Encephalitis is sometimes confused with encephalopathy, which is defined as a state of altered mental status without inflammation.

As the exact etiologic agent often varies between geographic locations, travel history is important to obtain. Other key history points: time since onset of symptoms, rashes, sick contacts with similar symptoms, animal/insect contact (especially ticks), sexual contacts, vaccinations, and immunosuppressed status (medication or advanced HIV).