Cerebral cavernous malformations (CCMs) are abnormally formed blood vessels. As opposed to other kinds of hemangiomas, CCM vessels, which have the appearance of a small mulberry, develop and create problems in the brain or spinal cord. These malformations, which can vary in size from 2 millimeters to several centimeters in diameter, may be hereditary but most often occur on their own.

CCMs may leak blood, leading to bleeding in the brain or spinal cord (hemorrhage). Brain or spinal hemorrhages can generate a wide range of more apparent neurological symptoms, depending on the location of a cavernous malformation in a person's nervous system.


Cerebral cavernous malformations (CCMs) may exist without apparent symptoms. Obvious symptoms tend to occur when recurrent episodes of bleeding or blood clot formation lead either to seizures, for upper lobe CCMs, or to focal or vision issues, for CCMs in the brainstem, basal ganglia and spinal cord.

Generally, signs and symptoms of CCMs may include weakness, numbness, difficulty speaking, difficulty understanding others, unsteadiness, vision changes or severe headache. Seizures also can occur, and neurological issues can progressively worsen over time with recurrent bleeding (hemorrhage). Repeat bleeding can occur soon after an initial bleed or much later, or a repeat bleed may never occur.

When to see a doctor

Seek medical help immediately if you experience any symptoms of seizure, or signs and symptoms that suggest brain hemorrhage, such as:

  • Sudden, severe headache
  • Nausea
  • Vomiting
  • Weakness or numbness on one side of the body
  • Difficulties in speaking or understanding speech
  • Loss of vision
  • Double vision
  • Balance difficulties


Most CCMs occur as a single formation, without an apparent cause and without any family history.

However, roughly 20 percent of affected people have a familial (inherited) form of the disorder. In many cases, such people can identify similarly affected family members, most often with multiple malformations. A diagnosis of the inherited form can be confirmed by genetic testing.

Some CCMs can also occur following focal brain radiation therapy.

Risk factors

As mentioned above, while most CCMs occur with no clear cause, the genetic (inherited familial) form of the condition can cause multiple cavernous malformations, both initially and over time.

To date, research has identified three genetic variants responsible for familial cavernous malformations, to which almost all familial cases of cavernous malformations have been traced.


The most concerning complications of CCMs stem from recurrent bleeding (hemorrhage), which may lead to progressive neurological damage.

Hemorrhages are more likely to recur in people with prior diagnosed hemorrhages. They're also more likely to reoccur with malformations located in the brainstem.

Cavernous malformations care at Mayo Clinic

May 18, 2018
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