A cerebral or intracranial aneurysm is a weakening of the inner muscular layer (the intima) of a blood vessel wall, resulting in a balloon-like outpouching. The vessel develops a blister-like dilation that can become thin and rupture without warning. The resultant bleeding into the space around the brain is called a subarachnoid hemorrhage (SAH). This kind of hemorrhage can lead to a stroke, coma and/or death. Several factors are believed to contribute to the formation of cerebral aneurysms. These include:
- Hypertension (high blood pressure)
- Cigarette smoking
- Congenital (genetic) predisposition
- Injury or trauma to blood vessels
- Complication from some types of blood infections
- Drug use (cocaine)
People who suffer a ruptured brain aneurysm may have warning signs, including:
- Severe, sudden, thunderclap headache (“worst headache of my life”)
- Nausea and vomiting
- Stiff neck
- Blurred or double vision
- Sensitivity to light (photophobia)
- Loss of sensation
- Confusion, lethargy
- Loss of consciousness
Many people with unruptured brain aneurysms have no symptoms. Others might experience some or all of the following symptoms, which may be possible signs of an aneurysm:
- Cranial nerve palsy (e.g., double vision, blurred vision)
- Dilated pupils
- Double vision, loss of vision
- Pain above and behind eye
- Localized headache
- Progressive weakness or numbness
- Memory issues
Computed Tomography (CT or CAT scan)
A diagnostic image created after a computer reads x-rays. In some cases, a medication will be injected through a vein to help highlight brain structures. Bone, blood and brain tissue have very different densities and can easily be distinguished on a CT scan. A CT scan is a useful diagnostic test for intracranial hemorrhage because blood can be seen over 99% of the time. CT Angiography (CTA) is a special CT scan using contrast dye to highlight the arteries of the brain, and is becoming at least the initial preferred diagnostic screening method if an aneurysm is suspected.
Magnetic Resonance Angiogram (MRA)
This is a noninvasive study which is conducted in a magnetic resonance imager. The magnetic images are assembled by a computer to provide an image of the arteries in the head and/or neck. The MRA shows the actual blood vessels and can help detect blockages, aneurysms, and vascular malformations. MRA does not provide more information about a cerebral aneurysm than a CTA of good quality, and takes much longer to perform (about 35 minutes). It is also contraindicated in patients with certain types of metallic implants. Its advantages over CTA are: 1) patients with iodine allergy are not excluded; and 2) there is decreased radiation exposure.
Cerebral Angiography (also called cerebral angiogram, carotid/vertebral angiogram) is an invasive test where a catheter is inserted into the femoral artery of the leg and contrast dye is then injected. X-rays are then taken to give a complete picture of the arteries and veins of the brain. Because the test is invasive, cerebral angiography carries a very small (0.5%) risk of stroke. Cerebral angiography is considered the gold standard test for evaluation of the blood vessels of the central nervous system.
Observation is considered a reasonable option if the aneurysm is very small, in a location that is felt to present a low risk of growth or rupture, or in elderly patients. If the aneurysm has ruptured or is considered large enough to pose significant risk for rupture, then treatment is usually recommended. Microsurgical clipping is performed through a craniotomy with small titanium clips to completely exclude the aneurysm from the circulation. Another option is endovascular coiling, which is done via a catheter inserted in the groin. Endovascular treatment feeds coils into the aneurysm to keep blood from entering it, subsequently clotting off the aneurysm. Both means of treatment have their risks and benefits and should be discussed with your surgeon in the decision-making process.