A weakness in a blood vessel in the brain that balloons and fills with blood.
Intracranial aneurysm is a weakness in a blood vessel in the brain. The vessel may balloon and fill with blood. Most occur between the underside of the brain and the base of the skull.
The aneurysm can leak or rupture, causing dangerous bleeding. A sudden, bad headache is a key symptom.
Emergency medical care is needed. Treatment includes surgery or another procedure to stop blood flow to the aneurysm.