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Cavernous Malformations of the Brain (Cavernomas)
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What is a
Cavernoma? |
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A cavernoma or
cavernous malformation is a vascular abnormality of the central
nervous system. It consists of a cluster of abnormal, dilated
vessels. Pathologically, it is red to purple in colour,
appearing as a raspberry. Cavernomas contain blood products at
various stages of evolution and are usually less than 3
centimetres in size.
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What are the
Causes of Cavernous Malformations? |
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Some individuals
are born with a tendency to develop cavernous malformations.
They are not a cancer, which means they cannot spread to other
parts of the body. Occasionally, people can have multiple
cavernomas.
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Who Gets a
Cavernous Malformation? |
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Cavernous
malformations occur in people of all races and sexes. The
male-female ratio is about equal. Family history may be positive
especially in patients of Hispanic descent. Recent work has
linked the predisposition to cavernous malformation to the
seventh human chromosome. Cavernomas can be found in any region
of the brain, be of varying size, and present with varying
clinical disorders. In a general population of 1,000,000 - .5%
or 5000 people may be found to have a cavernous malformation,
although many are not symptomatic.
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What are the
Symptoms of a Cavernous Malformation? |
- Seizures
- Progessive or transient neurologic deficits
- Bleeding
- Headache
It is important to
know that a cavernous malformation can be present and not
produce any symptoms. In fact, approximately 12% of patients at
our clinic are asymptomatic.
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Headaches and
Cavernous Malformations: |
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Headaches
accompany a cavernous malformation in many patients and may have
even precipitated the diagnostic evaluation uncovering the
lesion. 6-10% of patients with a cavernoma will report headaches
as an accompanying symptom.
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Progressive
or Transient Neurologic Deficits: |
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Patients may
present with double vision, unsteadiness, sensory disturbances,
and weakness or paralysis on one side of the body. These
complaints are closely related to where the lesion is located.
20% of patients will complain of these when they present to the
physician.
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Seizures and
Cavernous Malformations: |
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Sometimes
patients present to emergency with a seizure and upon
investigation of the seizure a cavernous malformation is found.
36% of patients with a cavernous malformation will present with
seizures.
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Bleeding from
a Cavernous Malformation: |
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Up to 25% of
patients will present with a hemorrhage. This is the most
serious complication of a cavernoma. If the cavernoma does
bleed, it usually, but not always, starts with a headache. The
headache starts suddenly and may be followed by nausea,
neurological problems or a decreasing level of consciousness.
Sometimes a bleed may be very small and produce very mild or no
symptoms at all.
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Why do
Cavernous Malformations Bleed? |
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We do not know of
any specific activity that provokes hemorrhage. We do not
recommend any restriction for our patients.
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What is the
Risk that a Cavernous Malformation will Bleed? |
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The risk depends
on where the malformation is located. Deep lesions in the
brainstem bleed and cause problems at a rate of 10% per year,
whereas symptomatic hemorrhage from a superficial lesion is very
uncommon. The risk with a superficial lesion is much lower (less
than 1% year).
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Diagnosis of
Cavernous Malformations: |
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There are two
main tests that are used to diagnose cavernomas. These are:
- Computerized Axial Tomography (CAT Scan)
- Magnetic Resonance Imaging (MRI)
MRI has provided the
ability to image and localize otherwise hidden lesions of the
brain and provide accuracy of diagnosis preoperatively. Both the
MRI and CAT scans produce images of slices through the brain.
These tests help the doctors to see exactly where the cavernoma
is located. Cavernomas cannot be seen on a cerebral angiogram.
The following are
indications to consider treatment of a cavernous malformation:
- Neurological dysfunction
- An episode of bleeding
- Intolerable symptoms
- Uncontrolled seizures
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Treatment of
Cavernous Malformations: |
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There are two
possible options available for patients who are found to have a
cavernous malformation:
NOTE: Alternatives
may exist to these two options, that your doctor will be happy
to discuss with you.
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* The statistics for the above
information were based on data obtained by the
University of Toronto Brain Vascular Malformation Study Group and published in
the paper Cerebral Cavernous Malformations: Natural History and Prognosis After
Clinical Determination With or Without Hemorrhage by Philip J. Porter, MD,
Robert A. Willinsky, MD, FRCSC, William Harper, MD and M. Christopher Wallace,
MD, FRCSC. Accepted for publication, J. Neurosurgery, 1997.
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