A brain aneurysm is a bulge or ballooning in a blood vessel in the brain.
An aneurysm in the brain often looks like a berry hanging on a stem. A brain aneurysm can leak or rupture, causing bleeding into the brain (hemorrhagic stroke). Most often a ruptured brain aneurysm occurs in the space between the brain and the thin tissues covering the brain.
A ruptured aneurysm quickly becomes life-threatening and requires prompt medical treatment.
Most brain aneurysms, however, don't rupture, create health problems or cause symptoms. Such aneurysms are often detected during tests for other conditions.
Bernard Bendok, M.D., neurosurgeon at Mayo Clinic in Arizona, explains the signs, symptoms and treatments for brain aneurysms.