Contents of This Section:

1. What is a cavernous malformation (cavernoma)?
2. How common is a cavernous malformation (cavernoma)?
3. Why does a cavernous malformation (cavernoma) develop?
4. What are the symptoms of a cavernous malformation (cavernoma)?
5. More about cavernous malformation (cavernoma) hemorrhage and rehemorrhage.
6. What are the complications of a cavernous malformation (cavernoma)?
7. How is a cavernous malformation (cavernoma) detected?
8. How is a cavernous malformation (cavernoma) treated?
9. Images of cavernous malformations (cavernoma) including brainstem cavernomas.

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 section 9., below, for an image). 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 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%; they are about as common as brain arteriovenous malformations (AVM), and far less common than brain aneurysms.

3. Why do cavernous malformations (cavernomas) 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) persons. 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 cavernous malformations (cavernomas)?

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.

5. More about cavernous malformation (cavernoma) 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 cavernous malformations (cavernomas)?

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 of the hemorrhage(s).

7. How are cavernous malformations (cavernomas) detected?

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.

8. How are cavernous malformations (cavernomas) treated?

The treatment is surgery. There is no effective radiation treatment for cavernomas. The one exception is a possible cavernoma variant that occurs in the venous sinuses (intrasinus cavernoma) which has been reported to be susceptible to radiation (e.g., gamma knife or stereotactic radiosurgery). There is some debate over the precise pathology of this intrasinus cavernoma; i.e., it may be a variant of a cavernoma, or a different vascular lesion altogether! Note that cavernomas can develop in regions of brain that have previously been exposed to radiation.

In general, a cavernoma that is enlarging radiologically and/or symptomatic should be given consideration for surgery. Even ones located in the brainstem or spinal cord or other highly "eloquent" areas should be considered for removal if symptomatic and if relatively safely accessible surgically (i.e., ones that are causing neurological problems and present themselves to the surface of the brain or brain stem or spinal tissue region). The relative risks vs. benefits of surgery should be considered on an individual basis, and discussed comprehensively. Cavernomas in the brainstem and spinal cord and other highly "eloquent" regions require a highly experienced neurosurgeon for safe and effective treatment.

9. Images of cavernous malformations (cavernoma) including of the brainstem.

Image 1: CAVERNOMA

Image 2 (above collage). A symptomatic ruptured brainstem (pontine) cavernoma. The patient had encountered episodic left-sided face numbness, hearing impairment and incoordination. A. MRI scan of the brain showed a large cavernoma (encircled in red) located in a part of the brainstem called the "pons". The critical "basilar artery" (tip of red arrow head) and the 7th and 8th cranial nerves (green arrow head) are seen near this brainstem cavernoma. The brainstem is the "highest-price real-estate" of the brain and is a challenge to safely approach and operate on. B. Intraoperative view of the patient's pons, with veins (2 mm diameter) on the right of this image, while on the left there are cranial nerves 7 (for facial muscle movement) and 8 (for hearing and balance). C. A small incision has been made into the pons, and the cavernoma's blood-stained cavity is now on view (in black circle). D. The cavernoma has been removed, and the surrounding discoloured brainstem tissue is seen. E & F. The preoperative and postoperative MRI (T1 sequence+contrast) sequences are shown here side-by-side. The cavernoma and haemorrhage products (between green arrow heads) were removed; some small amount of blood products remained, absorbed in time. In F., A "developmental venous anomaly" (DVA) or "venous angioma" (red arrow heads) is seen next to the previous cavernoma cavity; this DVA was intentionally not removed as it represents part of the normal venous drainage of this patient's brainstem. G. Postoperative CT scan image showing some small amount of blood products and a little air in the resection cavity which typically absorb in time. The patient was neurologically intact within 48 hours of surgery.

Image 3 (above collage). A symptomatic ruptured brainstem (cervico-medullary) cavernoma. This young patient presented with progressive weakness of all limbs (quadraparesis) and impaired bowel and bladder function. Without the appropriate surgical treatment, she would soon have become severely disabled. A. The preoperative MRI scan showed a cavernoma/cavernous haemangioma (in red circle) involving the lower brain stem (medulla) and uppper (cervical) spinal cord. Green arrow heads show the characteristic haemosiderin or iron pigment (dark staining here) deposited into the brain and spinal cord tissue by this long-standing cavernoma that had been subtly leaking blood for some time. B. Advanced MRI imaging using MR tractography software shows the region of the cavernoma (red circle) and the haemosiderin pigment (green arrow heads) and their relationship to the key movement pathyway of the limbs (corticospinal tract; shown in bright blue here as it passes through the brainstem and spinal cord). This cavernoma and its blood products displaced and squashed ("effaced") this critical tract causing much of the patient's debilitation prior to surgery. C. The intraoperative photograph shows the multiple small rasberry-like "caverns of blood" (sinusoids) of the cavernoma (in red circles) once an opening was very carefully made in the brainstem and spinal cord and the overlying membranes. The C1 and C2 nerve roots can be seen (yellow arrow heads). D. The postoperative MRI shows that the cavernoma has been removed. The haemosiderin pigment remains (this cannot be safely removed from the brainstem as viable nerve tissue exists in this highly eloquent area and must be preserved). The curative goal is removing the cavernoma. The patient is recovering very well postoperatively.ratively.

Image 3. The above panel shows a cavernous malformation located in a patient's fluid-filled cavity (ventricle) region, deep within the brain. The top-left MRI shows the cavernoma (red dotted circle) in the year 2007. The top-centre MRI shows the same cavernoma (red dotted circle) in the year 2008. It had become much more prominent due to repeated microhaemorrhages into it (depositing iron pigment - seen as the dark ring surrounding the mass - permanently into the brain tissue), and threatened to bleed into the ventricle itself. The top-right image shows the same cavernoma from a different perspective (in the red dotted circle). The lower-left image, a "MRI tractography map" obtained immediately before awake brain surgery for removal of this cavernoma, shows the cavernoma itself (in red dotted circle) close to the vision fibers (green tract at tips of yellow arrows) and the patient's face-arm-leg movement area (blue tract at tip of light blue arrow). The lower-centre MRI shows the cavernoma in the cross-hair of the operating microscope. Some dark blood-filled caverns are seen here, surrounded by the cavernoma's frondy light-reflective solid tissue component. The cavernoma is embedded in the ventricle cavity itself (V). The postoperative MRI scan is shown at the lower-right, the empty cavernoma cavity is now seen following complete removal of this mass. The patient has made an excellent recovery and has returned to work.

Image 4. The above panel shows a cavernous malformation located in a patient's expressive language area (of Broca), i.e., that part of the brain that generates speech. The patient presented with repeated and worsening bouts of speech impairment. The top-left MRI shows the cavernoma (red dotted circle) in the year 2000. The top-center MRI shows the same cavernoma (red dotted circle) in the year 2007. It has grown through repeated microhaemorrhages. The cavernoma itself (tip of the red arrow) is surrounded by areas of haemorrhage of different ages (green arrow, yellow arrow). The white rim around this entire area shows injury to the brain. The top-right MRI shows the cavernoma immediately prior to surgery. The lower-left image, obtained at the time of awake brain surgery for removal of this symptomatic cavernoma, shows the cavernoma itself (tip of red arrow) and an adjacent area into which this cavernoma has ruptured (tip of green arrow; iron pigment of hemosiderin -- natural yellow-brown stain noted here). The lower-right MRI (postoperative) shows that the cavernoma has been successfully removed. The patient is now neurologically intact, with no more speech impairment.