These vascular lesions of the brain, also referred to as angiographically
occult vascular malformations (AOVMs), are often confused with
true AVMs. While AOVMs may bleed they are less likely to do so
than AVMs and the bleeding is generally not as bad. AOVMs may
also cause seizures. Usually surgical removal of AOVMs is recommended
but for AOVMs in difficult areas, such as the brainstem, Gamma
Knife Radiosurgery may be useful.
Generally Gamma Knife treatment of AOVMs is recommended only
for lesions that have bled repeatedly or are causing intractable
seizures and cannot be removed surgically. Unlike true AVMs, AOVMs
do not usually disappear after Gamma Knife treatment. However,
several studies have shown that the rate of bleeding is greatly
reduced after Gamma Knife treatment.
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