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  Cavernous Malformation (Cavernoma):

Contents of this page, which is Cavernoma Page 1:

  1. What is a cavernous malformation/cavernoma? Click here
  2. How common are cavernous malformations/cavernomas? Click here
  3. Why does a cavernous malformation develop? Click here
  4. What are the symptoms of a cavernous malformations? Click here
  5. More about cavernoma hemorrhage and rehemorrhage. Click here
  6. What are the complications of a cavernous malformation? Click here
  7. How is a cavernoma detected (investigations)? Click here

Contents of Cavernoma Page 2:

  1. How is a cavernous malformation treated? Click here
  2. Images of cavernous malformations including brainstem cavernomas. Click here

 


1. What is a cavernous malformation/cavernoma?

A cavernous malformation, also known as a cavernous hemangioma or cavernoma, is an abnormal vascular entity (or "lesion") made up of many small compartments (lobules) like a bunch of small berries, or a mulberry (see Cavernoma Page 2 for images). These microcomparments contain blood (hemorrhagic) products in different stages of evolution. The "sinusoidal" compartments are enclosed by abnormally thin and quite fragile endothelialized walls. Unlike an arteriovenous malformation (AVM; take me to the AVM section now), there is no large feeding artery and no large draining vein in a cavernoma. However, there frequently is a venous angioma associated with the cavernoma! ( take me to the Venous Angioma section now ).

Most cavernomas are found in the larger (supratentorial) parts of the brain hemispheres, but up to 1 in 4 or 5 (i.e., 20-25% of all cavernomas) are found in the hindbrain (posterior fossa; infratentorial), especially in the pons region of the brainstem. Much less commonly a cavernoma may be found in the spinal cord (but this may be more likely to occur in patients with a family history of cavernous malformations).

2. How common are cavernous malformations/cavernomas?

They are not very common. Their prevalence (presence at any given time) in the population is probably somewhere between 0.1 - 0.5% (i.e., 1 in 200 to 1 in 1000 people in the general population); they are about as common as brain arteriovenous malformations (AVM), and far less common than brain aneurysms.

3. Why does a cavernous malformation develop?

Cavernomas occur sporadically (spontaneously in a noninherited manner) in the majority of cases, but in some cases may demonstrate inheritance (familial; i.e., a positive or strong family history of cavernous malformations). In familial cases, a specific chromosome 7 gene abnormality has been demonstrated, and familial cavernous malformation has been reported to be more common in hispanic (especially Mexican-American) people. In familial cases, cavernous malformations are more commonly multiple (i.e., two or more cavernomas present at the time of diagnosis), and may certainly also involve the spinal cord.

On chromosome 7, the specific two genes involved are refered to as CCM1 (band 7q11.2-q21; aka KRIT 1 because of its role in creating the KRIT 1 protein, or Krev interaction-trapped 1 protein), and CCM 2 (band 7p15-p13; controls production of the protein malcavernin). A third gene referred to as CCM 3 (on chromosome 3q) has been identified and is being investigated further.

 

4. What are the symptoms of a cavernous malformation?

Cavernomas may be asymptomatic, or may present with seizures (60%) or with progressive neurological impairment or "deficits" (50%). Some can present with hydrocephalus or raised intracranial pressure (headache, nausea, vomiting, visual disturbance, sleepiness) depending on their size and location. It is uncommon for cavernomas to cause sudden catastrophic or devastating neurological injury, but the progressive brain (or spinal cord) injury associated with cavernomas may be severely disabling as time goes on.

Why do these symptoms occur? The reason is repeated bouts of hemorrhage in the cavernoma. Different cavities of the cavernoma may have different ages of blood products. The walls are fragile, and the growth of micro blood vessels into these lesions results in blood product (hemosiderin) leeching around the cavernoma, and cycles of cavernoma growth through hemorrhage and rehemorrhage. The hemorrhage is rarely a large devastating hemorrhage.

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5. More about cavernous malformation hemorrhage and rehemorrhage.

The risk of hemorrhage from a cavernoma is somewhere between 0.5-1% per year. It may be greater (or at least easier felt symptomatically) in cavernomas located in more "eloquent" brain such as the basal ganglia, thalamus, brainstem, and spinal cord. The rehemorrhage rate varies in the literature, but is probably somewhere between 4-10% per year (some reports indicate an even higher rate in the first year or two following the first diagnosed cavernoma hemorrhage).

6. What are the complications of a cavernous malformation?

The major complications are seizures and progressive neurological impairment, and the type of "deficit" varies according to the size and location of the cavernoma, and the extent and multiplicity/frequency of the hemorrhage(s).

7. How is a cavernous malformation detected (investigations)?

Cavernomas are detected best through MRI. They can enhance with contrast, but frequently do not. They are not detectable on a cerebral angiogram (i.e., are referred to as angiographically occult vascular malformations or AOVMs; however, an associated venous angioma may be detected on the angiogram!). The best two MRI sequences used to detect cavernomas are regular T2 ("popcorn" appearance) and gradient echo (GRE; "India ink" blotch appearance). These are shown below. A CAT scan can also show a cavernoma, but the resolution is better with an MRI.

Note that in familial or multiple cavernoma patients, it is worthwhile screening the cervicothoracic spinal cord via MRI to exclude the presence of an occult cavernoma there.

 

 

 


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