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Overview of Cavernous Malformation

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A cavernous malformation is an abnormal berry-like cluster of deformed blood vessels that can bleed. Bleeding causes symptoms such as seizures, headaches, and a wide range of neurological problems (for example, weakness and/or difficulty with speech). Treatment options include observation, medications for symptoms, and surgery. Surgery is often curative. However, you might need to work with therapists to maximize recovery of speech or motor functions.

What Is a Cavernous Malformation?

A cavernous malformation is an abnormal berry-like cluster of warped capillaries, usually a few centimeters wide, that can occur in the brain or, rarely, in the spinal cord. Capillaries are small blood vessels only 1-cell thick that allow tissues to receive oxygen and various nutrients. In a cavernous malformation, the capillaries are leaky, less elastic, and enlarged with thinner-than-normal walls. Pooling of blood and the formation of blood clots in the cluster makes a cavernous malformation look like a mulberry or popcorn on imaging. Bleeding causes symptoms.

                                            Figure 1: Typical appearance of a cavernous malformation.

Figure 1: Typical appearance of a cavernous malformation.

What Are the Symptoms?

Up to 20% of people have no symptoms, and cavernous malformations are found incidentally with imaging. If it bleeds, seizures are the most common initial symptom. Other symptoms include headaches and a wide range of neurological problems, such as difficulty understanding others, difficulty speaking, unsteadiness, and vision problems. These changes are usually sudden and alarming.

What Are the Causes?

Cerebral cavernous malformations have been linked to a loss of function in genes KRIT1 (CCM1), MGC4607 (CCM2), or PDCD10 (CCM3). Up to half of the cases of cavernous malformation can be inherited and often present with multiple cavernous malformations. However, not all people with these gene mutations develop a cavernous malformation.

How Common Is It?

Cavernous malformations affect 0.3% to 0.5% of the population worldwide. In the United States, people of Hispanic origin have a higher prevalence of cavernous malformation than other ethnic groups. Symptoms are usually seen between the ages of 30 and 40 years.

How Is It Diagnosed?

Cavernous malformations are diagnosed by magnetic resonance imaging (MRI). On MRI, a popcorn-like mass is seen. MRI might need to be repeated to check if the cavernous malformation has changed in size or bled recently or if new lesions have formed. Unlike with arteriovenous malformations (AVMs), angiograms to visualize high blood flow are not performed, because blood in a cavernous malformation flows slowly and cannot be seen with angiography.

                                            Figure 2: MRI of a cavernous malformation, often described as a “popcorn” lesion on imaging.

Figure 2: MRI of a cavernous malformation, often described as a “popcorn” lesion on imaging.

What Are the Treatment Options?

Each year, cavernous malformations have a 1% to 5% risk of bleeding, and treatment depends on the location of the malformation, history, and symptoms. Observation might be preferred for incidental cavernous malformations that do not produce symptoms. Symptomatic patients with seizures can be managed initially with medications. However, a history of multiple bleeds increases the risk that another bleed will occur. In these cases, surgery might be recommended.


Cavernous malformations incidentally diagnosed in patients with no symptoms might be observed over time.


Patients with seizures caused by a cavernous malformation, especially one that is difficult to reach via surgery, can be placed on antiseizure medications. However, a risk of bleeding still exists.


Surgery is often the treatment of choice among patients with symptoms (seizures no longer treatable via medication) and a history of bleeds from the cavernous malformation. Complete removal of the cavernous malformation is usually the goal, because partial removal can be associated with higher rates of rebleeding. The exact approach depends on the location of the mass and its relation to nearby critical structures.

Once the cavernous malformation is reached, the caverns are dissected and decompressed. Any small arteries feeding into the cavernous malformation are coagulated and cut. After the cavernous malformation is pulled out, the edges of the cavity are inspected for residual pieces that are removed.

After surgery, patients typically undergo MRI within 24 hours to check for the presence of any remaining cavernous malformation. If present, an immediate reoperation is usually performed to prevent future occurrence of bleeding. Patients might undergo additional MRI 1, 3, and 5 years after surgery.

In this video, Dr. Cohen describes the techniques for microsurgical resection of a pontine cavernous malformation.

For more information about the technical aspects of the surgery and extensive experience of Dr. Cohen, please refer to the chapter on Brainstem Cavernous Malformation in the Neurosurgical Atlas.

                                            Figure 3: Surgical removal of a cavernous malformation in a minimally invasive fashion.

Figure 3: Surgical removal of a cavernous malformation in a minimally invasive fashion.

Complications of surgery depend on the location of the cavernous malformation due to invasion of normal brain tissue as the surgeon makes way toward the lesion. These can include bleeding or neurologic deficits such as weakness and difficulty with speech or understanding.

What Is the Recovery Outlook?

Surgery is often curative for cavernous malformations. If there are any neurologic problems such as weakness or speech difficulties, you can work with therapists before you go home or during your recovery. Depending on the complexity of your surgery, recovery can take up to 6 weeks before you can gradually resume your normal activities.



Capillary—thin blood vessels that form a network between arteries and veins to distribute oxygen and nutrients to tissues

Lesion—a region in a tissue that is damaged through injury or disease, such as a tumor or, in this case, a cavernous malformation

Contributor: Gina Watanabe BS


Cavalcanti DD, Kalani MYS, Martirosyan NL, et al. Cerebral cavernous malformations: from genes to proteins to disease: clinical article. J Neurosurg 2012;116:122–132.

Gunel M, Awad IA, Finberg K, et al. A founder mutation as a cause of cerebral cavernous malformation in Hispanic Americans. N Engl J Med 1996;334:946–951.

Del Curling O, Kelly DL, Elster AD, et al. An analysis of the natural history of cavernous angiomas. J Neurosurg 1991;75:702–708.