Cerebral Cavernous Malformation (CCM), often called a cerebral cavernoma, is an abnormal cluster of small blood vessels in the central nervous system. These lesions are comprised of thin-walled, dilated capillaries that resemble a small raspberry or mulberry. CCMs can occur anywhere in the brain or spinal cord and are considered one of the more common types of vascular malformation. While many people never experience symptoms, the presence of a cavernoma carries a risk of neurological problems, including hemorrhage. This overview details the structure of these malformations, the signs they produce, the methods used for diagnosis, and the available management options.
The Structure and Causes of Cerebral Cavernomas
A cavernoma is fundamentally a collection of abnormal, enlarged capillaries, known as caverns, which lack the typical supportive tissue found in normal blood vessels. Unlike healthy vessels, their walls are structurally fragile and less elastic. This inherent weakness makes them susceptible to recurrent, small leaks of blood, or micro-hemorrhages. This process leads to the accumulation of blood byproducts and iron deposits (hemosiderin) in the surrounding brain tissue.
Cavernomas are classified into two groups: sporadic and familial. The sporadic form represents the majority of cases, typically involving a single lesion, which is not inherited. The familial form is an autosomal dominant inherited condition, often resulting in multiple lesions that tend to present earlier in life.
Familial CCM is caused by a mutation in one of three known genes: CCM1, CCM2, or CCM3. These genes normally play a role in maintaining the integrity of blood vessel walls. A mutation leads to a loss of function within the endothelial cells, causing the characteristic structural defect. The CCM3 mutation is associated with a more aggressive disease course and an increased risk of bleeding compared to the other two genes.
Recognizing the Signs Common Symptoms
Symptoms depend on the lesion’s location and whether it has recently bled. The most common presentation is seizures, which occur because the lesion and surrounding iron deposits irritate the adjacent brain tissue. Seizures are often the initial symptom, especially for lesions located in the outer layers of the brain (supratentorial region).
Focal neurological deficits are another common symptom, resulting when the cavernoma is situated in an area controlling specific functions like movement or sensation. These deficits can include weakness, paralysis, numbness, difficulty with balance, or problems with speech and vision. When a symptomatic hemorrhage occurs, these deficits appear suddenly and may mimic a stroke.
Headaches can also occur, particularly if a significant bleed has led to a severe, acute onset of pain. Many patients experience fluctuating symptoms, where deficits appear and then partially resolve. This transient nature is often attributed to minor, recurrent micro-hemorrhages or localized swelling (edema) around the lesion. Some individuals remain asymptomatic, and the cavernoma is discovered incidentally during a scan for an unrelated issue.
Confirming the Diagnosis Imaging and Testing
The diagnosis relies primarily on specialized medical imaging, as these lesions are often “angiographically occult.” This means they do not typically show up on conventional angiography due to their slow, low-pressure blood flow. Magnetic Resonance Imaging (MRI) is the definitive method for identification, providing detailed images of the brain structure.
On an MRI, a cavernoma is described as having a “popcorn” or “mulberry” appearance due to mixed signals from blood at various stages of breakdown. The most telling feature is a surrounding ring of low signal intensity, known as a hemosiderin rim, which represents chronic iron deposits from previous micro-hemorrhages. Specific MRI sequences, such as Susceptibility-Weighted Imaging (SWI), are highly sensitive and can reveal even the smallest lesions and the multiple lesions often seen in familial cases.
While a Computed Tomography (CT) scan may be used in an emergency setting to quickly detect a large, acute hemorrhage, it is less effective for diagnosing the cavernoma itself. The cavernoma may appear as a non-specific dense mass on a CT scan, and smaller lesions can be missed entirely. For patients with a family history or multiple lesions, genetic testing and neurological consultation may also be part of the comprehensive diagnostic workup to identify a familial cause.
Treatment and Management Options
The management strategy depends on whether the patient has symptoms, the lesion’s location, and the risk of future hemorrhage. For individuals whose cavernoma is found incidentally and is asymptomatic, the primary approach is observation, often called watchful waiting. This involves regular monitoring with periodic MRI scans to track the lesion’s stability or growth. The annual risk of a first-time symptomatic hemorrhage in an asymptomatic cavernoma is relatively low, estimated between 0.4% and 2.4% per year.
For patients experiencing seizures, medical management using anti-epileptic drugs (AEDs) is the first line of defense to control the electrical instability in the brain. If the cavernoma is symptomatic—such as causing drug-resistant seizures or a progressive neurological deficit—and is located in an accessible part of the brain, surgical resection is the preferred treatment. Microsurgery allows for the complete removal of the lesion, which has a high success rate for controlling seizures and eliminating the risk of future hemorrhage from that specific malformation.
A secondary or alternative approach is Stereotactic Radiosurgery (SRS), used for lesions that are deep or located in eloquent brain areas where surgery would carry a high risk of neurological damage. SRS uses highly focused radiation beams to target the lesion, with the goal of causing the blood vessels to gradually close off, or thrombose, over time.
While multiple studies suggest SRS can significantly reduce the annual hemorrhage rate after two years, it is considered a controversial option for cavernomas. This is primarily because the full benefits may take time to appear, and the procedure carries its own risks of radiation-induced side effects. The decision to pursue any intervention is a careful balance between the risk posed by the cavernoma’s natural history and the potential risks of the treatment itself.