Cerebral Cavernous Malformations: What to Know

Medically Reviewed by Brunilda Nazario, MD on January 25, 2022

Cerebral cavernous malformations, or CCMs, are irregular bundles of tiny blood vessels (capillaries) in the brain. The vessels are stretched out more than usual. Their abnormal shape and thinner walls can lead them to leak or alter blood flow, which may cause health problems.

CCMs range in size from less than a quarter of an inch to 4 inches.

What Are the Symptoms of CCMs?

In about 25% of cases, CCMs don’t cause any medical problems or symptoms Typically, when symptoms do show up, they first appear between the teenage years and age 50 (though infants and children sometimes show signs of CCMs too).

Symptoms may differ according to the location of the CCMs. They may emerge quickly and then subside as bleeding from blood vessels is reabsorbed into the body. Possible signs or symptoms include:

Less commonly, you or your doctor may notice:

  • Unusual muscle growth
  • Unusual skin texture or growth
  • Buildup of calcium in the brain
  • Extra growth of blood vessels in your eye (specifically in the retina)

What Causes CCMs?

The walls of the tiny blood vessels, or capillaries, that make up CCMs are thinner than usual, which makes them more likely to leak. The walls also lack certain fibers that normally make blood vessels able to stretch out and then stretch back. So, when their shape changes because of high blood flow, these vessels tend to stay in odd open spaces that doctors call “caverns” -- thus, their name cavernous malformations.

In most cases, doctors don’t know what causes CCMs. In about 20% of cases, people with CCMs inherit it from their parents. Scientists have identified some genes that seem to play a role in the formation of CCMs, but more research is needed.

How Do Doctors Diagnose CCMs?

If your doctor suspects CCMs, they will take a full medical history, examine you in person, and ask you about any symptoms. They will take pictures of your brain with an MRI, electroencephalogram (EEG), or CT scan to look for certain blood flow patterns that suggest a CCM. They also may use blood tests and genetic analysis to make a final diagnosis.

How Do Doctors Treat CCMs?

Your doctor may simply treat the symptoms of your CCMs. For example, they may prescribe anti-epileptic medications to treat seizures caused by CCMs, pain meds for headaches, and rehabilitation exercises for physical symptoms like weakness or partial paralysis.

If doctors discover your CCMs without symptoms, they will likely want to monitor them by MRI on a regular basis. In some cases, they may suggest anticonvulsant medications to protect against possible future symptoms like seizures.

In some serious cases, your doctor may want to address the CCM directly. They may talk to you about possible surgery. In general, this is when the following conditions are met:

  • You’re unable to control seizures with medication.
  • The CCM is clearly the cause of the seizures.
  • The CCM is in a low-risk spot for brain surgery.

Your doctor may also consider surgery if you’ve had at least one brain hemorrhage that caused symptoms or if you have slowly worsening symptoms due to CCM. In these cases, as always, you and your medical team will have to weigh the risk of surgery against its possible benefits.

What’s the Outlook for Someone With CCMs?

The outlook varies greatly, depending on the individual case.

Many people with CCMs won’t ever know they have the condition because they won’t have any symptoms. (About a quarter of people never have symptoms.) Others may have only minor or occasional symptoms they can easily manage with rest and medication.

More serious cases, though, can cause life-changing or even permanent symptoms. Where possible, these cases may require surgery.

Unfortunately, doctors don’t know of a way to prevent CCMs. Scientists hope that research on genes will eventually lead to preventive treatments.

Show Sources


NIH Genetic and Rare Diseases Information Center: “Cerebral cavernous malformation.”

American Association of Neurological Surgeons: “Cavernous Malformations.”

Johns Hopkins Medicine: “Cavernous Malformations.”

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