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What are cavernous malformations?
What causes cavernous malformations?
What are the symptoms of cavernous malformations?
How do cavernous malformations cause damage?
How are cavernous malformations diagnosed?
How are cavernous malformations treated?
What are cavernous malformations?
A cavernous malformation (also known as cavernoma, cavernous angioma, familial hemangioma, or congenital vascular cavernous malformation) is a benign abnormality in the brain where small, mulberry-like dilated blood vessels aggregate into rounded masses within the substance of the brain itself or its coverings. Blood flow into these lesions is from very small low-flow blood vessels in the brain, as opposed to arteriovenous malformations (AVMs), which are larger blood vessel abnormalities with a large amounts of rapid blood flow. Cavernous malformations can range in size from that of a dime to several inches in diameter.
What causes cavernous malformations?
These lesions are generally thought to appear during fetal development; however, there is a tendency for them to enlarge over time, which is thought to be a result of small non-symptomatic hemorrhages inside of the malformation. Lesions that are similar to cavernous malformations have also been seen in the brain following radiation therapy for treatment of brain cancer, implying that the cause of these malformations is likely some type of injury to blood vessels in susceptible individuals. Genetic factors may also play a role since there are certain families where most members are affected with multiple cavernous malformations.
What are the symptoms of cavernous malformations?
The most common presentation for cavernous angiomas is generally gradual or rapid onset of a neurologic deficit of some type such as weakness or sensation changes in an arm or leg. Other symptoms include seizures, headaches, irritability (in children) or changes in personality. Some of these lesions are also discovered incidentally when the patient has brain imaging for another reason.
It is estimated that the rate of hemorrhage of a cavernous malformation is approximately 0.7-1.7% per year. The majority of these bleeds are small and may not produce any symptoms. Large hemorrhages are rare and it is also uncommon to be left with a permanent neurological deficit from a hemorrhage unless the cavernous angioma is located in a sensitive location, such as the brain stem. If a cavernous malformation causes more than one symptomatic hemorrhage, the chances of further hemorrhage increase significantly -- in these cases treatment, rather than expectant management, is highly recommended.
How do cavernous malformations cause damage?
The symptoms caused by cavernous malformations are due to leakage of blood from these lesions which can lead to pressure and/or irritation of functioning brain tissue adjacent to the cavernous angioma. The bleeding from such abnormal vessels tends to be slow and intermittent; however, rapid hemorrhage can also be seen which causes a sudden onset of symptoms. The bleeding rate of cavernous malformations is extremely variable from one patient to another; and, although bleeding from these lesions can cause serious neurologic deficits, most patients recover well over time and the hemorrhages are rarely fatal, unless the lesion itself is located in a critical area and there are repeated hemorrhages. Therefore, the choice of treatment should be individualized to each patient based on the location and size of the lesion as well as the history of symptoms over time.
How are cavernous malformations diagnosed?
The most frequently employed imaging technology for detection of cavernous malformations is magnetic resonance imaging (MRI). Computed tomography (CT) scans can also be used to reveal evidence of bleeding; although, MRI offers superior diagnostic information by using magnetic fields to detect subtle changes in brain tissue. Angiography, which involves guiding a thin catheter into brain arteries followed by injection of dye and acquisition of x-rays, is not a good diagnostic tool for cavernous malformations since the blood flow within them is very slow and only very tiny blood vessels supply the malformation.
How are cavernous malformations treated?
There are many factors that determine whether or not a cavernous malformation should be treated. Non-symptomatic (incidentally discovered) lesions can be followed with MRI scans for signs of growth, yearly for 2 years, then every 5 years thereafter. An MRI should be performed sooner if there is any clinical evidence of hemorrhage or new symptoms.
For lesions that present with seizures, medications can be started, in order to avoid surgery. If the seizures can not be controlled, even with multiple medications, and if the cavernous malformation is in an easily accessible area of the brain, then surgical removal of the lesion may be indicated.
Surgery may also be a reasonable treatment option if there have been clinically significant (neurologically symptomatic) hemorrhages and if the cavernous malformation is in an easily accessible location. For lesions in functionally important areas of the brain, surgical removal should be contemplated following the second clinically relevant hemorrhage since such patients are more likely to have further hemorrhages that may leave them with significant neurologic deficits.
