neurologic disorders
Encephalitis
Introduction
Encephalitisis inflammation of the parenchyma of the brain, resulting from direct viral invasion or occurring as a postinfectious immunologic complication caused by a hypersensitivity reaction to a virus or another foreign protein. Symptoms include fever, headache, and altered mental status, often accompanied by seizures or focal neurologic deficits. Diagnosis requires cerebrospinal fluid analysis and neuroimaging. Treatment involves antiviral drugs when indicated (eg, in herpes simplex virus encephalitis) and is otherwise supportive. (See also Introduction to Brain Infections .) 