CAVERNOUS HEMANGIOMAS
Also known as "Cavernomas" and "Cavernous Malformations", These lesions have been found with increasing frequency over the past few
years because of the incredible accuracy of MRI scanning. They arise from
the tiny vessels that separate the arterial system from the venous system
of the brain. There is some controversy as to whether the cavernomas are
true vascular malformations or very slow growing tumors of capillary blood
vessels. They are characterized as truly benign lesions, and can be completely
removed and cured by surgical removal. However, as many of these lesions
are found coincidentally, they are often left alone if no evidence of hemorrhage
is present at the time of the MRI study.
They may induce seizures; occasionally, their removal leads to seizure
control when medical therapy fails. When they are noted along with hemorrhage,
they most often do not cause neurologic devastation, as do brain aneurysms
and AVMs. The reason for this has to do with the very low vascular pressure
within these malformations.
Consequently, the usual volume of hemorrhage is small, causing temporary
deficits that generally improve (not completely). We now know that the
cavernomas do grow slowly over time, and that once they hemorrhage, they
tend to do so again. Each subsequent hemorrhage is usually followed by
a stepwise deterioration in neurologic function, causing the patient to
lose something with each bleed. When they are found in the brainstem, the
most compact and important part of the brain, cavernomas may represent
a threat to a patient's life. As might be expected, even a 5cc hemorrhage
into the jam-packed area of the brainstem may cause difficulty swallowing,
double vision, loss of facial function, and even loss of consciousness.
TREATMENT OPTIONS
No Therapy
When found incidentally, with no prior history of problems related to the
discovery of one of these lesions, most physicians will follow them with
serial MRI scans over the following years. Small lesions in difficult places
are often left alone, even if they are responsible for seizures. The same
is true when the risk/benefit ratio for surgical removal may not allow
the surgeon to go ahead.
Surgical Removal
Ironically, the best time to remove these lesions is soon after they
have hemorrhaged. The reason for this is that the hemorrhage does some
of the surgeon's work for him, separating the lesion from the surrounding
brain. This makes the removal easier, and also limits some of the potential
downside of surgery. Patients who have lesions that have bled previously,
but not recently, are occasionally told to wait for their next hemorrhage
before considering surgery, usually due to the difficult location of their
cavernoma. When easily accessible, large, responsible for serious hemorrhage
or for uncontrollable seizures, surgical removal is the way to go. Once
removed, these lesions are cured.
Difficult to access lesions require 3-D computer image guided sterotactic
surgical systems. In cases of patients with multiple cavernous malformations
(these may run in families), only symptomatic or dangerous lesions are
excised. A serious problem arises when a pregnant woman has multiple cavernomas.
These present a real challenge, especially if the mother has had previous
hemorrhages.
Radiation Therapy
There is no evidence that radiation therapy does anything for Cavernous
Hemangiaomas. Focus beam radiation (e.g. Gamma Knife) is currently being
recommended by some physicians; however no long term results (including
radiation damage, malignant tumor induction etc.) are in as yet.
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