A cavernoma is a cluster of abnormally formed, small blood vessels, or capillaries, typically found within the brain or spinal cord. These vascular formations look similar to a raspberry or a popcorn kernel on imaging, containing blood-filled spaces called caverns. The primary concern associated with these lesions is their tendency to leak blood, which can lead to localized bleeding or hemorrhage.
Understanding the Structure of a Cavernoma
A cavernoma is a low-flow lesion, unlike other vascular malformations such as arteriovenous malformations (AVMs). It is a collection of enlarged, deformed capillaries whose walls are structurally weak and thin. These vessels lack the supportive muscular and elastic layers found in normal blood vessels.
This fragile structure makes the lesion prone to repeated, small episodes of bleeding, known as micro-hemorrhages. The vessel cluster contains no intervening brain tissue, distinguishing it from healthy brain matter. Surrounding the malformation, the brain tissue often develops scar tissue (gliosis) and deposits of hemosiderin, an iron-containing substance resulting from the breakdown of blood products.
Cavernomas can occur anywhere in the central nervous system, which dictates the type and severity of symptoms. Locations are categorized as supratentorial (above the tentorium cerebelli) or infratentorial (including the brainstem and cerebellum). Brainstem cavernomas are particularly challenging because this area controls involuntary, life-sustaining functions, and a small bleed can have a significant impact.
Signs and Symptoms of Brain Cavernomas
Many cavernomas remain asymptomatic throughout a person’s life, often discovered incidentally during imaging for unrelated reasons. When a cavernoma becomes symptomatic, the presentation depends on the lesion’s size and exact location within the brain. The most common symptom is an epileptic seizure, which occurs when the lesion irritates the surrounding brain tissue.
Symptomatic lesions may also cause focal neurological deficits, including weakness or numbness in the limbs, problems with balance, double vision, or difficulty with speech. Headaches are a frequent complaint, sometimes occurring suddenly due to a bleed or becoming chronic.
The severity of symptoms is closely tied to whether the cavernoma has bled and the size of the hemorrhage. While most bleeding events are small and reabsorbed by the body, a larger hemorrhage can cause stroke-like symptoms. This puts pressure on the surrounding brain tissue, though symptoms can fluctuate as the brain recovers and the body absorbs the blood.
Causes and Diagnostic Confirmation
Cavernomas are classified into two main types: sporadic and familial. The sporadic form is the most common, typically presenting as a single lesion with no known family history, and the cause remains unknown.
The less common familial form is characterized by multiple lesions throughout the brain and spinal cord. This genetic type is linked to specific mutations in genes, notably CCM1, CCM2, and CCM3. Individuals with the familial form have a fifty percent chance of passing the condition on to their children.
Diagnosis relies on sophisticated imaging techniques, with Magnetic Resonance Imaging (MRI) being the gold standard. MRI visualizes the distinct characteristics of the malformation, including its mixed-signal core surrounded by a rim of hemosiderin. This appearance is often described as the “popcorn” or “mulberry” sign, reflecting the stages of blood degradation within the lesion.
While a Computed Tomography (CT) scan may be performed initially, it is not the most effective diagnostic tool as it can miss characteristic features. Specialized MRI sequences, such as susceptibility-weighted imaging (SWI), highlight hemosiderin deposits from past micro-hemorrhages, which appear as a dark rim. The presence of these specific imaging findings confirms the diagnosis and distinguishes the cavernoma from other brain lesions.
Treatment and Long-Term Monitoring
For asymptomatic cavernomas discovered incidentally, the standard management is observation. This involves regular neurological checkups and periodic MRI scans to monitor the lesion’s size and stability. The decision to intervene is complex, depending on the patient’s symptoms, the lesion’s history of bleeding, and its location.
When symptoms are present, medical management is the initial approach, particularly for seizures. Anti-epileptic drugs effectively control seizure activity caused by the lesion’s irritation of the brain tissue. This treatment manages the secondary effects of the malformation without requiring lesion removal.
Surgical resection is considered the definitive treatment and is recommended for lesions that have caused a significant hemorrhage or intractable seizures. Neurosurgery is most straightforward for superficial lesions accessible on the brain’s surface. Complete removal eliminates the risk of future bleeding from that specific lesion.
For cavernomas located in deep, surgically inaccessible areas, such as the brainstem or basal ganglia, stereotactic radiosurgery is an alternative. The efficacy of radiosurgery remains controversial, though some studies suggest a reduction in future bleeding risk after a latency period. This approach carries risks of radiation-related complications, including swelling and new neurological deficits.