A cerebral aneurysm is a lump or expanding part of a blood vessel in the cerebrum of the brain. It resembles a berry on a stem.
A cerebral aneurysm can rupture, causing seeping of blood into the brain, a condition that is also known as hemorrhagic stroke. Usually, a ruptured aneurysm is located in the space between the brain and the thin tissues that are covering it. This kind of hemorrhagic stroke is known as a subarachnoid hemorrhage.
A ruptured aneurysm rapidly progresses toward becoming more dangerous and requires immediate medical treatment. Most cerebral aneurysms, however, do not rupture, nor create medical issues or cause symptoms. Such aneurysms are frequently diagnosed with the help of tests.