Ruptured aneurysm

A sudden, severe headache is the key symptom of a ruptured aneurysm. This headache is often described as the "worst headache" ever experienced.

Common signs and symptoms of a ruptured aneurysm include:

• Sudden, extremely severe headache
• Nausea and vomiting
• Stiff neck
• Blurred or double vision
• Sensitivity to light
• Seizure
• A drooping eyelid
• Loss of consciousness
• Confusion

'Leaking' aneurysm

In some cases, an aneurysm may leak a slight amount of blood. This leaking (sentinel bleed) may cause only a:

• Sudden, extremely severe headache

A more severe rupture often follows leaking.

Unruptured aneurysm

An unruptured brain aneurysm may produce no symptoms, particularly if it's small. However, a larger unruptured aneurysm may press on brain tissues and nerves, possibly causing:

• Pain above and behind one eye
• A dilated pupil
• Change in vision or double vision
• Numbness of one side of the face

When to see a doctor

Seek immediate medical attention if you develop a:

• Sudden, extremely severe headache

If you're with someone who complains of a sudden, severe headache or who loses consciousness or has a seizure, call 911 or your local emergency number.

Brain aneurysms develop as a result of thinning artery walls. Aneurysms often form at forks or branches in arteries because those sections of the vessel are weaker.

Although aneurysms can appear anywhere in the brain, they are most common in arteries at the base of the brain.