A cavernoma, also referred to as a cavernous malformation or cavernous angioma, is a vascular abnormality found within the central nervous system. This condition involves a cluster of abnormal, small, tightly packed blood vessels. These lesions are considered vascular malformations, not tumors, and often resemble a small berry or raspberry. A cavernoma causes problems when its thin walls leak blood into the surrounding tissue of the brain or spinal cord.
Defining Cavernoma Structure and Location
The structure of a cavernoma is characterized by an irregular collection of dilated, thin-walled capillaries, often described as having a “mulberry” or “blackberry” appearance. These vessels are distinct from normal capillaries because they lack the necessary structural support, specifically the layers of elastic tissue and smooth muscle. This deficiency makes the cavernoma vessels fragile and prone to leakage into the surrounding neural tissue.
The spaces within the malformation, known as caverns, contain slow-moving blood that is often clotted. Cavernomas range in size from a few millimeters up to several centimeters in diameter. While they can form anywhere in the body, they primarily cause symptoms when they develop in the brain (called cerebral cavernous malformations, or CCMs) or in the spinal cord.
The location of the lesion heavily influences the severity of the condition. Cavernomas in the brainstem (which controls involuntary functions like breathing and heart rate) or in the cerebral cortex (which governs speech and motor abilities) can lead to significant neurological deficits even from small bleeds. Lesions in the spinal cord can cause serious issues, such as weakness or sensory loss, depending on the compressed nerve pathways.
Causes and Risk Factors
Cavernomas are classified into two main types: sporadic and familial. The sporadic form is the most common, accounting for the majority of cases, and typically presents as a single lesion with no known family history. In contrast, the familial or hereditary form is passed down in an autosomal dominant pattern, meaning a child has a 50% chance of inheriting the condition if a parent is affected.
Familial cases are characterized by multiple cavernomas throughout the central nervous system. This hereditary type is linked to mutations in specific genes, most notably CCM1 (also called KRIT1), CCM2, and CCM3 (also called PDCD10). The loss of function in one of these genes within blood vessel cells is the mechanism for lesion formation.
A less common risk factor for developing new cavernomas is prior exposure to radiation therapy directed at the brain or spine, often occurring years after the initial treatment. This suggests that while genetics play a strong role, environmental factors and random genetic changes can also lead to the formation of these vascular clusters.
Recognizing the Signs of Cavernoma
Many cavernomas remain asymptomatic throughout life and are only discovered incidentally during brain imaging for an unrelated condition. When symptoms arise, they are typically the result of bleeding (hemorrhage) from the fragile vessels or pressure exerted on the surrounding neural tissue. The most common first sign of a symptomatic cavernoma is an epileptic seizure, particularly focal seizures, which occur because the malformation is irritating the surrounding brain tissue.
Seizures occur in a significant portion of symptomatic patients, often due to the chronic presence of blood breakdown products like hemosiderin, which is highly irritating to the brain. The type and severity of symptoms are directly related to the cavernoma’s location. When a cavernoma is located in a functionally important area, it can cause focal neurological deficits.
These deficits include weakness or numbness in the limbs, problems with balance and coordination, visual disturbances like double vision, or difficulties with speech. A more dramatic presentation occurs with an acute hemorrhage, which manifests suddenly as a severe headache accompanied by nausea and vomiting. These bleeding events can sometimes mimic a stroke, causing rapid onset of neurological symptoms depending on the amount and location of the blood leaked.
Diagnosis and Management Options
The definitive method for identifying a cavernoma is Magnetic Resonance Imaging (MRI). MRI is considered superior to Computed Tomography (CT) scans because it clearly visualizes the small “caverns” of blood and the characteristic rim of hemosiderin (iron deposits) from previous microbleeds. This distinct appearance on MRI, sometimes described as “popcorn-like,” allows clinicians to distinguish cavernomas from other vascular malformations, which are often invisible on imaging like angiography due to low blood flow.
Once diagnosed, the management strategy is tailored to the individual patient, depending on whether the lesion is causing symptoms and its location. For asymptomatic lesions, or those discovered incidentally, the standard approach is watchful waiting, involving regular monitoring with periodic MRI scans. This conservative management is preferred when the risk of intervention outweighs the risk of the lesion itself.
If a cavernoma is symptomatic (such as causing seizures uncontrolled by medication or resulting in progressive neurological deficits), surgical resection is often the preferred treatment. Microsurgical resection aims for complete removal of the malformation, which provides the best chance of preventing future bleeds and resolving seizure activity. However, surgery is only recommended for lesions that are safely accessible, as the goal is to remove the lesion without causing new neurological damage.
For deep-seated or inaccessible cavernomas, particularly those in the brainstem, stereotactic radiosurgery may be considered. This technique uses highly focused radiation to target the lesion. Its effectiveness in completely eliminating the risk of future hemorrhage is still debated among specialists, especially when compared to the efficacy of complete surgical removal. Treatment for symptoms like seizures is often handled with anticonvulsant medications, even when a more invasive intervention is not immediately required.