Cerebral Aneurysms and Subarachnoid Hemorrhage
A brain aneurysm is a weakness in the wall of an artery causing a ballooned-out portion or a swelling in the blood vessel. The thin walls of an aneurysm can burst and cause bleeding into the tissues of the brain.
Symptoms of a Cerebral Aneurysm
There usually are few symptoms of a brain aneurysm. Sometimes, brain aneurysms press on a nerve or leak small amounts of blood before a major rupture, thus producing warning signs. These symptoms, which can occur minutes to weeks before a rupture, include:
- Severe headache
- Pain behind one eye
- Double vision, droopy eyelid or other vision problems
An actual rupture can produce the following symptoms:
- A sudden, severe headache
- A brief loss of consciousness that often follows the onset of the headache. Some people remain in a coma, but most often patients wake up feeling confused and sleepy. Within a few minutes or few hours, the patient may again begin to feel confused and sleepy.
- Vomiting
- Dizziness
- Frequent fluctuations in the heartbeat and breathing rate often occur
- Seizures
- Paralysis on one side of the body or neurologic problems (usually occuring in about 25% of the people who have subarachnoid hemorrhages)
Causes and Risk Factors for A Cerebral Aneurysm
Aneurysms most likely are conditions a person is born with. The weak spot may not start ballooning out until later in adulthood. As the aneurysm becomes larger and the balloon wall becomes thinner, the risk of the aneurysm bursting grows.
Research tends to show that people who smoke are more likely to have aneurysms that rupture. People who have uncontrolled high blood pressure also may have a greater risk of a ruptured aneurysm.
Certain diseases that run in families appear to be linked to brain aneurysms. For example, people who have a family history of polycystic kidney disease and brain aneurysms should be screened.
Diagnosing Cerebral Aneurysms
A magnetic resonance angiogram (MRA) is used to screen for unruptured brain aneurysms. At this point, there is some small evidence to suggest that aneurysms run in families. Ongoing genetic studies are being done to investigate this possibility.
Because brain aneurysms are silent until they cause bleeding into the brain, a timely diagnosis can be difficult. The diagnosis of a subarachnoid hemorrhage can usually be made with a computed tomography (CT) scan. If the CT scan is not conclusive, a lumbar puncture (spinal tap) can be done to confirm or rule out the diagnosis.
Approximately 40% of those who have a subarachnoid hemorrhage die during the hemorrhage because of extensive brain damage. Without proper treatment for the brain aneurysm, 20 to 30% will have a second bleed within the first month and those who survive three months have approximately a 3% chance every year of having another episode of bleeding. Recurrent bleeding has a 70% mortality rate. Because of the ominous prognosis with delayed definitive therapy, referral to a center of excellence with experience in treating subarachnoid hemorrhage is imperative.
Treating Cerebral Aneurysms
Cerebral aneurysms tend to be silent until they rupture and bleed. This makes it difficult to diagnose them before a life-threatening emergency occurs.
A ruptured cerebral aneurysm should be treated as soon as possible. Once an aneurysm has bled, there is a 4% chance it will bleed again in the first day. The risk of renewed bleeding remains high for two weeks after the first bleed. The more an aneurysm bleeds, the greater the chance of a major stroke or death.
There are two basic treatments for aneurysms whether they rupture or not:
- the aneurysm, which is the traditional approach and involves making a window in the skull and placing a clamp over the weakened part of the artery
- Coil embolization, in which tiny platinum coils are placed in the aneurysm to seal it off. This allows blood to flow normally through the artery. This approach is minimally invasive. It is very similar to angiogram, where tubes are threaded through an artery to allow the coils to be placed.
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