Which condition is characterized by inflammation of the brain tissue, often due to infection?

• A. Brain tumor
• B. Brain abscess
• C. Meningitis
• D. Encephalitis

Answer: (D)

Encephalitis is inflammation of the brain tissue itself, usually caused by an infection such as a virus. Because the brain parenchyma is involved, you see neurologic symptoms like altered mental status, confusion, seizures, and sometimes focal neurological deficits, often with fever. This differentiates it from a brain abscess, which is a localized pus-filled infection within the brain and tends to present with signs of a localized lesion; from meningitis, which is inflammation of the membranes surrounding the brain and spinal cord and typically presents with severe headache, neck stiffness, and photophobia rather than primary brain-tissue inflammation; and from a brain tumor, which is an abnormal growth rather than an inflammatory process. So the description best fits inflammation of the brain tissue due to infection—encephalitis.