A cavernoma, also known as a cerebral cavernous malformation (CCM), is an abnormal cluster of small blood vessels typically found in the brain or, less commonly, the spinal cord. This vascular anomaly is characterized by thin, dilated, and irregular capillaries that lack the proper supportive structure of normal blood vessels. The lesion has a propensity to leak blood, which can lead to various neurological problems, though many people remain without symptoms. Understanding the nature of a cavernoma, how it is identified, and the available management options is important.
Understanding the Physical Structure of a Cavernoma
A cavernoma is a vascular malformation composed of tightly packed, enlarged capillaries that resemble a raspberry or a mulberry. These lesions are made up of numerous small, blood-filled sacs or “caverns,” which gives the condition its name. Unlike healthy blood vessels, the walls of a cavernoma are thin and lack the typical supportive tissue found in the central nervous system.
This compromised structure makes the vessels highly susceptible to leakage, causing blood to ooze into the surrounding brain tissue. The blood flow within a cavernoma is characteristically slow, distinguishing it from other vascular malformations like arteriovenous malformations (AVMs), which involve high-pressure flow. Repeated leaking leads to the accumulation of old blood products, particularly iron-containing hemosiderin, which forms a rim around the lesion.
Cavernomas can range in size from a fraction of an inch up to several centimeters and can occur anywhere in the central nervous system. Most cases are sporadic, appearing as a single lesion without a family history. However, in about 20% of cases, the condition is familial, caused by a genetic mutation that typically results in a person having multiple cavernomas.
Recognizing the Signs and Symptoms
Many individuals with a cavernoma never experience symptoms; the lesion is often discovered incidentally during an imaging scan for another reason. When symptoms do occur, they result from the cavernoma bleeding or irritating the surrounding brain tissue. The clinical presentation varies widely depending on the lesion’s size, number, and location within the brain.
Seizures are the most common initial symptom, particularly when the cavernoma is located in the cerebral cortex (the outer layer of the brain). These seizures occur because the malformed vessels and surrounding areas of old blood irritate the nearby brain cells. A hemorrhage, even a small one, can cause new or worsening neurological deficits.
Focal neurological deficits can manifest as weakness or numbness in the limbs, problems with vision or balance, or difficulties with speech. Cavernomas located in the brainstem are concerning because even a small bleed in this area can lead to severe issues like facial paralysis or difficulty swallowing. Headaches are also a frequent symptom, often related to minor bleeding events or increased pressure within the head.
How Cavernomas Are Diagnosed
The diagnosis of a cavernoma typically occurs after a person presents with symptoms like a seizure or a sudden neurological change. The definitive method for confirming the presence of a cavernoma is Magnetic Resonance Imaging (MRI). MRI is sensitive because it can clearly detect the characteristic appearance of the lesion and the remnants of past bleeds.
On an MRI scan, a cavernoma often has a distinctive “popcorn” or “mulberry” appearance, surrounded by a dark ring. This dark ring is the hemosiderin deposit left from previous microhemorrhages, which helps distinguish the cavernoma from other types of brain lesions. Specialized MRI sequences, such as susceptibility-weighted imaging (SWI), are often used because they are highly effective at highlighting these small blood products and detecting smaller lesions.
While a Computed Tomography (CT) scan can quickly detect acute or new bleeding in the brain, it is not sensitive enough to reliably identify the cavernoma itself. Angiography, which maps blood flow, is generally not useful because of the slow-flow nature of cavernomas, making them “angiographically occult.” Genetic testing may also be recommended for individuals who have multiple lesions or a family history of the condition.
Treatment and Management Strategies
The treatment strategy for a cavernoma depends on several factors, including whether the lesion is causing symptoms, its location, and whether it has bled before. For individuals with an asymptomatic cavernoma, the standard approach is observation and monitoring. This involves periodic follow-up MRI scans, typically once a year, to check for changes in the lesion’s size or evidence of new bleeding.
Symptom management is a major component of care, particularly for seizures, which can often be controlled with anti-seizure medications. If a cavernoma has bled and caused significant neurological problems, or if seizures become difficult to manage, active intervention is usually considered. Surgical resection, which involves the complete removal of the lesion, is the only method that offers a definitive cure and eliminates the risk of future hemorrhage.
Surgery is typically performed when the cavernoma is easily accessible and located in an area of the brain where the risk of the procedure is low. For lesions located deep within the brain or in functionally sensitive areas where surgery carries a high risk of damage, stereotactic radiosurgery (SRS) may be an alternative. SRS uses a highly focused beam of radiation to cause the blood vessels in the cavernoma to gradually thicken and scar. This can reduce the risk of future bleeding after a latency period, usually two years.