Cavernous Malformations

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A cavernous malformation (CM), sometimes called cavernous angioma or cavernoma, is a small, berry-like mass of expanded blood vessels. The condition occurs relatively frequently in children. These blood vessel malformations obtain their blood supply from very small low-flow blood vessels in the brain, as opposed to certain high flow arterial arteriovenous malformations (AVMs), which have large amounts of rapid blood flow coursing through them. Cavernous angiomas can range from less than dime-sized to larger than orange-sized.

Cavernous malformations can form throughout the body, but those in the brain and spinal cord are dangerous. The risk comes from their tendency to bleed, which can put pressure on nearby brain tissue and interfere with the functions controlled by that area of the brain. The symptoms your child experiences will, therefore, vary with the location of the malformation.



Most CMs are diagnosed after an episode of bleeding causes the loss of some neurological function, resulting in weakness, dizziness, seizures or headaches. In most cases, that function gradually returns as the blood becomes reabsorbed. The symptoms are caused by the pressure of blood accumulation in and around the cavernous angioma. The bleeding from such a blood vessel malformation can be slow and intermittent (subacute) or it can be rapid, causing a sudden onset of symptoms. Headache and/or seizures are also frequently seen. In a series of 55 patients treated by Dr. Michael Scott here at Children's Hospital, the most common set of symptoms was gradual or rapid onset of a neurologic deficit such as weakness or sensation changes in an arm or leg. The second largest group of patients came in with seizures, and the third with headaches, irritability or changes in personality.




On MRI scans (magnetic resonance imaging) these lesions often have a very typical appearance. The malformation shows up as very distinct from the surrounding brain tissue and a radiologist will often be able to see areas of old and recent bleeding nearby. On CT (computed tomography) scans they appear as rounded areas that have a slightly higher density than the rest of the brain. An arteriogram (a test where dye is injected directly into the arteries that supply the brain and x-ray pictures taken) is typically used to diagnose an AVM; cavernous angiomas, however, are rarely seen on arteriograms because the blood flow within them is very slow and only very tiny blood vessels supply the malformation.




Cavernous malformations appear to be congenital -- that is, a patient is born with them -- although there are several instances where their development over time has been carefully documented by serial MRI scans. Lesions that are microscopically similar to cavernous angiomas can occur years following radiation therapy to the brain for the treatment of leukemia or tumors of the brain, implying that some type of injury to blood vessels by the radiation therapy may lead to the development of these malformations in susceptible individuals.

In studies based at Boston Children's Hospital, about 25 percent of patients had a strong family history of cavernous malformations. A family history component is likely if other family members have had hemorrhages within the brain at an early age, if multiple members of a family have a seizure disorder, or if there are associated blood vessel abnormalities on the skin. If a child has multiple cavernous angiomas the likelihood of a positive family history also is higher than normal. In these cases, it may make sense to have siblings tested for cavernous malformations.

Once a CM is diagnosed, many parents want to know if physical activity will cause it to bleed. There is little evidence of any relationship between physical activity and bleeding episodes and many patients with cavernous angioma lead normal, active lives. Nonetheless, it may make sense to avoid high-impact activities such as football.




The main treatment options for cavernous malformations are long-term observation or surgery. Many people with this condition can go their whole lives without noticing any ill effects, so it may make perfect sense to simply wait and see. If your child's CM has begun to bleed, it is more likely that surgery will be recommended. Surgery for a cavernous malformation is relatively easy for the neurosurgeon since these malformations can usually be separated from the surrounding brain and since bleeding from the malformations is relatively easy to manage during the operation. If the lesions are small or deep within the brain, computerized guidance techniques can help to locate them accurately.

The neurosurgeons at Boston Children's Hospital generally will remove a single, symptomatic lesion if it is easily accessible to the surgeon, if it is located in an area of the brain where the surgery itself will not cause or provoke neurological deficits, and if the lesion can clearly be identified as the cause of the patient's symptoms. When multiple cavernous angiomas show up in the course of an evaluation, the decision becomes more difficult. It can be hard to determine which CM is causing symptoms and surgeons are reluctant to operate on multiple malformations without evidence that it will improve the patient's symptoms. A course of observation and re-evaluation if symptoms recur sometimes is the safest policy to undertake in this situation.

Some researchers report average "rebleeding" rates -- that is how often a patient might experience a second bleed. Neurosurgeons at Boston Children's Hospital have noticed that this rate varies widely from one person to the next, so they will sometimes counsel patience to see if your child is one of the lucky ones with a low likelihood of rebleeding, especially if the lesion is deep and risky to treat.




The use of stereotactic radiosurgery to treat cavernous malformation is an area where reputable groups disagree about best practices. At Boston Children's Hospital the neurosurgeons have found that radiosurgery usually leads to swelling which may require long-term steroid treatments. It also does not completely obliterate the malformation and symptoms may persist years after the treatment. At Boston Children's Hospital, radiosurgery is used only as a last resort when surgery is too dangerous and symptoms become intractable.



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