Aneurysms

How do they develop?
What are the risk?
How is an aneurysm diagnosed?
Why should it be treated?
What are the treatment options?

How do they develop?

      It is not clear why a person develops a cerebral aneurysm. They are very uncommon in patients below 20 years of age and are increasingly common in older patients. In people over 65, they may be found in as high as 5% of the population. It appears that they are related to the absence of a muscular layer that makes up part of the blood vessels, which over time stretch and thin and create the aneurysm. Smoking appears to markedly increase the chance of developing a cerebral aneurysm.

What are the risks?

      Aneurysms can rupture and bleed into the brain, causing a stroke or even death. This is called a hemorrhage, which is usually quite serious. It is estimated that approximately 30,000 people in the United States suffer an aneurysm rupture each year. The results from these bleeds are quite serious. It has been estimated that if 5 people suffer a bleed today, in one year, only one person will be alive and well; another person will be disabled and three will be dead. Once aneurysms bleed, they have a high incidence of recurrent bleeding in the days following. There are also delayed problems of water on the brain (also known as hydrocephalus) and narrowing of the blood vessels due to the irritation on the vessels (known as vasospasm). Rebleeding, hydrocephalus, and vasospasm can happen days to weeks after the initial bleed. Aneurysms can and do grow. If they reach a certain size, usually over 25 mm, (one inch), they can start putting pressure on the surrounding brain tissues and cause progressive problems. These are called Giant aneurysms.
Taken together, all aneurysms appear to bleed at about a 4 % per year rate, or a 1/25 chance of bleeding. It should be noted that most small aneurysms under 6 mm (1/4 inch) are very unlikely to bleed.

How is an aneurysm diagnosed?

      If a cerebral aneurysm bleeds, the patient almost always has a severe headache that prompts the patient to seek medical attention. A CT scan of the brain or a Lumbar puncture usually identifies the blood that has leaked out of the vessel in a Subarachnoid Hemorrhage (SAH). An angiogram is usually performed to identify the exact source of bleeding and the detailed anatomy of the aneurysm.
Occasionally, aneurysms grow and press on the surrounding areas in the brain and cause other symptoms such as headache or double vision. This will prompt an MRI / MRA that may identify an aneurysm that has not bled.

Why should it be treated?

      Treatment of the aneurysms can be used to
      • Keep them from rebleeding
      • Treat the hydrocephalus
      • Treat the vasospasm.
      The major danger is caused by rebleeding in the days to weeks following the initial bleed.

 

What are the treatment options?

      To avoid rebleeding, aneurysms can be treated with direct surgery or radiology intervention (coiling). Direct surgery is performed under general anesthesia because skull and the outer skin of the brain must be opened to identify the aneurysm. A clip is then put across the junction between the normal blood vessel and the weakened ballooned aneurysm.
Radiology intervention, which does not require opening of the skull, is the preferred treatment option of the two. It is performed by first injecting a small tube (catheter) into the leg artery, then navigating it to the aneurysm under X-ray guidance. Tiny platinum coils or latex or Silicone balloons are used to fill the aneurysm. The materials that are used to treat aneurysms are new and considered investigational, therefore require a special consent. Patient selection is based on the individual patient and aneurysm anatomy. Occasionally, a number of procedures must be performed to safely obliterate the aneurysm.