Many people first notice an intracranial aneurysm only when it ruptures, with a sudden, extremely severe “worst headache of my life,” often with nausea, vomiting, stiff neck, light sensitivity, confusion, or loss of consciousness—this is a medical emergency. When unruptured, warning signs can be subtle or absent; some notice new, focal headaches, vision changes (double vision, droopy eyelid), pain around or behind one eye, or weakness or numbness on one side of the face. Others discover an aneurysm incidentally during brain imaging done for unrelated reasons, such as after a minor head injury or for persistent headaches.