A cerebral cavernous malformation (CCM) is an abnormal cluster of small blood vessels within the brain. These vascular lesions are not cancerous growths. They can occur in various parts of the central nervous system, including the brain and spinal cord.
What is a Cerebral Cavernous Malformation?
A cerebral cavernous malformation consists of thin-walled capillaries that form a cluster, often described as having a “mulberry-like” appearance. These vessels lack normal brain tissue and structural support from smooth muscle and elastic materials. This weakness can lead to slow-moving, clotted blood within the malformation and a tendency to leak.
CCMs can range in diameter from less than a millimeter to several centimeters. While they can appear anywhere in the brain or spinal cord, approximately 20% are found in the brainstem. Most CCMs are sporadic, occurring as a single malformation without a family history, and often have an associated developmental venous anomaly (DVA). About 20% of individuals with a CCM have a genetic, familial form, characterized by multiple malformations.
Recognizing the Symptoms
Symptoms associated with CCMs can vary considerably, depending on the malformation’s size and location within the brain or spinal cord. Seizures are among the most common presenting symptoms, affecting 40% to 70% of individuals with familial CCMs. Headaches are also frequently reported, occurring in 10% to 30% of cases.
Focal neurological deficits, such as weakness or numbness in the arms or legs, trouble speaking, or issues with memory and attention, can occur, especially if the CCM is located in areas like the spinal cord, brainstem, or basal ganglia. Bleeding within the malformation, known as hemorrhage, is a significant complication and can cause acute symptoms. Some individuals, however, may remain asymptomatic throughout their lives, with up to 50% of those with familial CCMs never experiencing symptoms.
How CCM is Diagnosed
The primary method for diagnosing cerebral cavernous malformations is Magnetic Resonance Imaging (MRI). MRI, particularly with sequences like gradient-echo or susceptibility-weighted imaging (SWI), detects blood products (hemosiderin deposits) that often surround these lesions due to recurrent microhemorrhages. These specific MRI techniques are sensitive to the magnetic properties of iron in blood, making CCMs clearly visible.
Other imaging techniques, such as CT scans or conventional angiography, are less effective at detecting CCMs. This is because CCMs are angiographically occult lesions, meaning their slow blood flow makes them difficult to visualize with methods relying on rapid blood movement. While these other imaging studies might rule out other conditions, MRI remains the standard for CCM diagnosis. A neurological examination is performed as a preliminary step to assess symptoms and guide further diagnostic imaging.
Treatment Options for CCM
Treatment decisions for cerebral cavernous malformations are individualized, taking into account the patient’s symptoms, the malformation’s location, and the risk of future hemorrhage. For individuals with asymptomatic CCMs, conservative management, often called watchful waiting, is a common approach. This involves regular monitoring with MRI scans to observe any changes in the malformation.
Medications are used to manage symptoms, such as anti-seizure drugs for those experiencing epileptic events. Surgical removal is a primary treatment option for symptomatic and accessible lesions, particularly if there has been a hemorrhage or if seizures are difficult to control. Stereotactic radiosurgery, which uses focused radiation, may be considered as an alternative in specific, complex cases where surgical removal is not feasible. However, its long-term effectiveness for CCMs is an area of ongoing research, and its use is often weighed against potential risks.