Clinical Reasoning: a 44-year-old woman with headache followed by sudden neurologic decline

A 44-year-old woman with a history of migraines and idiopathic intracranial hypertension presented to the emergency room with 1 day of headache and nausea. She had been otherwise healthy with no sick contacts. She was afebrile without nuchal rigidity, rash, or cardiac murmur, and her neurologic examination was normal. Migraine therapy was initiated with IV prochlorperazine, ketorolac, and magnesium. Two hours later, she developed fever (101.4°F) and confusion, continually stating, “It hurts,” but unable to answer questions or follow commands despite an otherwise unremarkable examination. Noncontrast head CT demonstrated mastoid sinus opacification, but no abnormalities of her brain parenchyma or ventricular system.