An intracranial infection means germs have reached the brain or its coverings. The immune system sounds an urgent alarm, and symptoms climb quickly. Fever is usually first. Temperature spikes to 38–40 °C (100–104 °F) and can swing from chills to sweats within an hour. Headache follows fast. It feels like steady pressure or a band tightening around the skull and grows worse when you move your head or bend forward. Neck stiffness appears early. Tilting the chin toward the chest feels like a pulled muscle, and bright light may make the pain spike. Nausea and vomiting hit without stomach upset.... Learn more