This little-known brain disorder sounds pretty scary, and it runs in families.

By Claire Gillespie
September 14, 2020
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The new TV series, Away, dropped on Netflix earlier this month, and at the heart of this space drama is a little-known brain condition called cerebral cavernous malformation (CCM). Hilary Swank stars as NASA astronaut Emma Green, and Josh Charles takes the role of her on-screen astronaut husband, Matt Logan. While Swank's character embarks on a mission to Mars, her husband stays behind; he's paralyzed from a stroke caused by CCM, which he's lived with his whole life. According to the National Institute of Health, CCMs affect about 16 to 50 per 10,000 people worldwide—but what are they, exactly? 

What is CCM?

A CCM is a collection of tightly packed, thin-walled blood vessels in the brain that can cause brain bleeding, Michael Walsh, MD, a neurosurgeon at Northwestern Medicine Lake Forest Hospital in Illinois, tells Health. CCMs can range in size from a few fractions of an inch to several inches in diameter, according to National Institute of Neurological Disorders and Stroke, depending on the number of blood vessels involved.

While the condition sounds scary, CCMs usually have a lower risk of bleeding than many other blood vessel abnormalities, and often they don’t cause any symptoms. Many people live their entire lives with a CCM without knowing they have one, says Dr. Walsh. 

Cavernous malformations, also called lesions, can actually form anywhere in the body, according to the NIH, but usually only result in serious symptoms when they occur in the brain and spinal cord. 

What causes CCM? 

It's not known what causes a CCM itself, says Dr. Walsh. However, the condition sometimes run in families and is passed from parent to child; it's the result of mutations in at least three genes (KRIT1, CCM2, and PDCD10). People with this form typically have multiple CCMs. The condition can also be sporadic, meaning there's no family history of CCM. People who have sporadic CCM usually only have one malformation. 

If symptoms occur, what are they?

When CCMs do cause symptoms, it’s often as a result of minor bleeding, says Dr. Walsh. Possible symptoms are headache, seizure, and stroke-like signs such as numbness, weakness, or difficulty speaking. 

“The symptoms vary depending on the location of the malformation in the brain,” Howard Riina, MD, neurosurgeon and director of NYU Langone’s Center for Stroke and Neurovascular Diseases, tells Health. If it’s in a “silent” part of the brain, such as some parts of the frontal lobe or cerebellum, the patient may simply experience a mild headache. If the malformation is in the motor cortex, however, it may cause weakness. A seizure can be a sign if the CCM is in the temporal lobe , and if it’s located in the brain stem, the outcome may be more serious, such as a hemorrhage. 

“The good news is the malformations are typically very small when they present and bleed relatively infrequently, approximately a half a percent a year,” explains Dr. Riina. 

How is CCM treated?

If symptoms lead to a diagnosis of CCM, doctors may decide to observe it with periodic imaging via an MRI to make sure it isn't changing. A CCM can shift in size over time, or more can appear, and a larger number of malformations increases the severity of the disorder. If a patient experiences seizures as a result of a CCM, medications are often used to control them, says Dr. Walsh. 

When multiple episodes of bleeding or repeated seizures occur, doctors may decide to do surgery to remove the CCMs. “Brainstem lesions are among the most difficult to manage,” says Dr. Riina. “If a lesion has bled several times and come close to the surface, we remove it.” 

If there is concern that other family members may also have CCM, genetic counseling can help find out. In one episode of Away, Swank and Charles' on-screen teenage daughter, Alexis, chooses genetic testing to find out if she too may be predisposed to developing a CCM. (Spoiler alert: Turns out she doesn't have a genetic predisposition.)

Can CCM be fatal?

Dr. Riina says it would be unusual for a CCM to be fatal. “Death would be more likely to be an effect of the seizure (if it occurred while swimming or showering, for example) rather than the bleed itself,” he says. However, a brain hemorrhage related to a CCM could be fatal. 

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