Cavernous Malformations

Cavernous malformations, also called cavernous venous malformations or, when in the brain, cerebral cavernous malformations, occur when blood vessels don’t form correctly.

In this condition, tiny blood vessels called capillaries group together. They grow with extremely thin walls that can leak (bleed) easily. These clusters of blood vessels (lesions) can be less than 1/4 inch to 4 inches in size.   

Cavernous malformations can form anywhere in the body, but are most likely to cause symptoms when they grow in the brain or spinal cord. Common symptoms include headaches or seizures. Experiencing symptoms depends on where the lesions grow and how many of the lesions are present.

Most of the time, these formations cause no problems. Many people never know that they have one. In some people, however, the lesions can burst and bleed into the brain, causing neurologic problems, including stroke and, in rare instances, death.

Facts about cavernous malformations

About one in 100 to 200 people have cavernous malformations. The malformations probably form before or shortly after birth. Some may seem to appear and disappear over time on subsequent MRI scans.

About 25% of people with cavernous malformations in the brain never have symptoms.  

In some instances, the condition is caused by mutations in particular genes. These familial cavernous malformations are inherited from a parent. In other cases, the malformations appear without a family history.


Symptoms of cavernous malformations depend on the location and size of the malformation. Although children sometimes have symptoms, most people who have symptoms are between 20 and 50 years old.

These are physical symptoms:

  • Headaches

  • Seizures

  • Changes in hearing or vision

  • Weakness

  • Paralysis

  • Difficulty thinking clearly or with remembering things

Complications of cavernous malformations include:

  • Hemorrhage (stroke)

  • Headache

  • Seizure

  • Death

When to call the doctor

Many people only find out about a cavernous malformation when it bleeds. This causes stroke in some people. If you notice symptoms, such as seizure, numbness, vomiting, or physical weakness, go immediately to the emergency room or call 911 to get help.


Doctors typically take a medical history and do a physical exam. The final diagnosis is usually made based on imaging tests that show areas of blood flow. These tests could include:

  • MRI scan

  • Electroencephalogram

  • CT scan

  • Blood tests

  • Gene testing is available in some clinics


A treatment plan could include:

  • Medication for symptoms, such as antiepileptic drugs for seizures

  • Surgery to remove the blood vessels

  • Performing an MRI at regular intervals to keep an eye on a lesion 


Currently, cavernous malformations can’t be prevented. Researchers hope that by learning more about the genes linked to these growths, prevention could become possible. Prenatal genetic testing and counseling are options for the first person in a family with multiple cavernous malformations or for relatives of those with identified familial cavernous malformations.