Cavernous malformations are clusters of abnormal, small blood vessels that can form in the brain or spinal cord. These formations resemble a raspberry and have thin, leaky walls that make them susceptible to bleeding. While many individuals with these malformations might not experience any symptoms, their presence carries a potential for complications due to their tendency to hemorrhage.
What Are Cavernous Malformations?
Cavernous malformations, also known as cavernomas or cavernous angiomas, are a type of vascular anomaly characterized by irregularly shaped, dilated blood vessels. Unlike other vascular malformations, these lesions contain slow-moving or stagnant blood and lack the typical structure of normal brain tissue between the vessels. They commonly appear in the cerebral hemispheres, but can also be found in deeper brain structures like the brainstem or spinal cord.
A hemorrhage can range from microscopic seeps that cause no noticeable symptoms to larger, more significant bleeds. The accumulation of blood can irritate surrounding brain tissue, potentially leading to various neurological issues. While these malformations are not cancerous, their location and the impact of a bleed can significantly affect a person’s health.
Understanding the Death Rate
The overall death rate directly attributed to cavernous malformations is relatively low, though a severe hemorrhage can lead to serious neurological damage or be fatal. Mortality rates following surgical removal are very low, generally less than 1% to 2% for those in sensitive areas like the brainstem, and between 0% and 1.9% across all locations.
For individuals whose cavernous malformations are managed without surgery, particularly those in the brainstem, reported fatality rates vary. One cohort study observed a fatality rate of 1.7% in untreated brainstem cavernous malformations. While some older reports cited higher mortality rates, more recent comprehensive reviews indicate these figures are significantly lower, with an overall mortality rate around 2.3% for conservatively managed brainstem lesions.
The annual risk of a cavernous malformation rupturing and causing a symptomatic hemorrhage typically ranges from 0.4% to 2.4% per year for a first bleed. This risk can increase significantly if the malformation has already bled. After an initial symptomatic hemorrhage, the annual rebleeding rate can be much higher, ranging from 3.8% to 29.5%, with some studies indicating approximately a 20% chance of rebleeding within the first two years.
Factors Influencing Risk
Factors influencing the risk of a severe bleed or fatal outcome include the malformation’s location. Lesions in the brainstem, which controls many basic life functions, are associated with a higher risk of symptomatic hemorrhage and can lead to more severe neurological deficits if they bleed. Deep or infratentorial locations also generally carry an increased risk compared to those in the cerebral hemispheres.
A history of previous hemorrhages is another strong predictor of future bleeding. Once a cavernous malformation has bled, the likelihood of it bleeding again increases considerably. Most re-hemorrhages are estimated to occur within five years of the initial bleed, with an approximate 42% risk during this period, after which the re-hemorrhage rates tend to decrease. The size of the lesion can also impact risk, with larger volumes, such as those 300 mm³ or greater, being identified as a significant predictor of bleeding.
Genetic factors also contribute to an individual’s risk profile. Approximately 20% of cavernous malformations are familial, linked to mutations in genes like KRIT1 (CCM1), CCM2, and PDCD10 (CCM3). Individuals with these familial forms often develop multiple lesions and may experience a higher annual hemorrhage rate compared to those with sporadic, single lesions. Other influencing factors include the presence of an associated developmental venous anomaly (DVA), which can be related to worsened outcomes.
Management and Prognosis
The management of cavernous malformations is highly individualized, taking into account the lesion’s location, whether it has caused symptoms, and the patient’s overall health. For asymptomatic individuals with a single lesion, watchful waiting is often recommended. This involves regular magnetic resonance imaging (MRI) scans to monitor the malformation for changes or new bleeding events.
When a cavernous malformation causes symptoms such as recurrent hemorrhages, seizures that do not respond to medication, or progressive neurological deficits, surgical removal may be considered. This approach aims to completely resect the malformation to prevent future bleeding and alleviate symptoms. Surgery is typically favored for lesions that are accessible and located in areas of the brain where the risk of surgical complications is acceptable.
For deep-seated or surgically challenging lesions, stereotactic radiosurgery (SRS) is sometimes considered as an alternative. This method uses focused radiation to target the malformation, though its effectiveness in reducing hemorrhage rates for cavernous malformations remains a topic of ongoing discussion among medical professionals. The long-term outlook for individuals with cavernous malformations varies widely, emphasizing the importance of personalized care and continuous monitoring to manage potential risks and maintain quality of life.