What are cavernous malformations?
Cavernous malformations are a group or clusters of abnormal capillaries—small, thin-walled blood vessels. These abnormal capillaries have bulges or pockets that fill with slow moving blood. They can occur anywhere in the body but usually only cause serious problems in the brain and spinal cord. Cavernous malformations in the brain are called cerebral cavernous malformations (CCMs). They also may be referred to as a cavernous angioma or cavernoma.
Most CCMs are found in the outer layer of the brain called the cortex, but they can also be found in other locations of the brain. They are often described as looking like small mulberries.
Signs and symptoms
Most people never find out that they have a CCM, as they don’t experience any symptoms or related health issues. Others experience symptoms due to the location of the CCM or if the CCM has bled. Others may find they have CCMs after surveillance following positive genetic testing.
These symptoms may include:
- seizures
- severe headache
- weakness, numbness or tingling in the arms or legs
- difficulty speaking
- problems with memory and attention
- problems with balance and walking
- changes in vision—seeing double
If the CCM has bled, symptoms may get progressively worse over time.
Symptoms that occur due to bleeding from a CCM near the brain stem may include:
- ataxia or issues with movement/coordination
- problems with speaking
- swallowing difficulties
- facial paralysis (unable to move the muscles of the face)
- continuous hiccups
- breathing difficulties
Bleeding from a CCM in the spinal cord may cause bowl and bladder symptoms or trouble with movement or feeling in the arms or legs.
Causes of cavernous malformations
A single CCM usually occurs without any known cause or family history.
If your child has multiple CCMs, they may have familial cavernous malformation syndrome, which is genetically inherited from family members who also have cavernous malformations. It is important to get genetic testing if there is a family history of CCMs. Genetic variants that can cause CCMs include the genes KRIT1 (CCM1), CCM2 and PDCD10 (CCM3).
Another cause of CCMs can include previous radiation to the brain or spinal cord, for example, as part of treatment for a brain tumour.
CCMs occur in 0.5% of the population. They are quite rare.
Of those who are diagnosed with a CCM, the majority (85%) are the type that occur without any known cause or family history. About 15% of all CCM’s diagnosed are the kind that occur due to a family history or exposure to radiation.
Diagnostic imaging and genetic testing
Diagnostic imaging is important in identifying CCMs. There are different types of imaging that can be performed:
- Computed tomography (CT) scan: A CT scan uses X-rays and a computer to take “slice-like” pictures of the brain. Sometimes, further CT imaging is done with contrast dye to take additional pictures of the vessels of the brain. This is called a CT–Angiogram.
- Magnetic resonance imaging (MRI): An MRI uses a strong magnet to take a picture of the brain. The images of the arteries in the brain are called MRI–Angiograms (MRAs), and the images of the veins in the brain are called MRI–Venograms (MRVs). MRI is the best diagnostic tool for assessing CCMs, and should include specific susceptibility weighted images (SWI) to establish whether there is one or more than one lesion.
Different from other vascular lesions, cerebral angiograms are not helpful for detecting CCM’s as the blood flows through them slowly making them not detectable on angiogram. Angiograms should only be done if there is a concern that an arteriovenous malformation (AVM) is being considered.
Since genetics may also play a role in the development of CCMs and impact other family members, it is important to discuss with your child’s health-care team whether genetic testing should be done to see if there is a genetic change or variant.
Medications
Medications may be used to treat some symptoms caused by CCMs, such as headaches or seizures. However, there are currently no medications to treat CCMs directly.
Treatment for children without symptoms
If a CCM is not causing any symptoms, the treatment plan may include simply monitoring the malformation. This would involve regular follow-up visits, using MRI scans to watch for any changes. It is very important to update your child’s health-care team if you notice any developing symptoms.
Treatment for children with symptoms
The main treatment option for CCMs if they are causing significant symptoms is open surgery (craniotomy and surgical removal).
Your child will be assessed by a group of neurovascular specialists including neurosurgeons, neurologist and interventional neuroradiologists. Your child’s treatment recommendations will be made based on their age, health status, and the size and location of the CCM.
Open surgery (craniotomy and CCM removal)
Your child’s neurosurgeon will make an incision on the scalp and remove part of the skull bone temporarily to access the CCM. With surgical equipment, the CCM is located and carefully removed. The skull bone is then re-attached, and the incision is closed.
After surgery, your child will spend some time in the neurosurgery unit. The team will check neurological function frequently. Most children remain in hospital for few days. Pain is managed with medication.
Prevention
Although CCMs are not preventable your child should be monitored with surveillance imaging to determine if any changes, bleeding or development of new lesions.
Complications
CCMs can bleed in the brain or spinal cord. Depending on the location, this may cause different signs or symptoms. The most concerning location for a CCM bleed is near the brainstem.
Symptoms can get progressively worse if a CCM bleeds more than once. A CCM can rebleed after the first bleed even after a lot of time has passed, or it may never bleed again.
Helping your child
Receiving the diagnosis of a CCM can be very stressful and emotional. Your child’s health-care team can suggest resources that may be available for you and/or your child to help to with coping.
For more information on coping, see:
- Living with a chronic condition: Overview
- Living with a chronic condition: Helping your child manage their health
- Living with a chronic condition: Maintaining your child's everyday routines
- Living with a chronic condition: Supporting yourself as a caregiver
- Mental health learning hub
- Guided audio meditations
- Mental health animations for kids and teens
For more information on seizures, see:
- Signs and symptoms of seizures
- Types of seizures
- What to do in case of a seizure
- Epilepsy: How to keep your child safe inside and outside the home
- Driving with epilepsy
For more information on caring for your child at home after a craniotomy, see Craniotomy.
Follow-up care
Your child will require several years of follow-up care and imaging to monitor the CCM, assess for any new CCMs, and (if treated) to ensure there is no evidence of it coming back.
When to seek medical attention
It is important to take your child to the nearest Emergency Department if they experience any of the following symptoms:
- Severe headache
- Seizure
- Weakness, numbness or loss of movement in an arm, leg or one side of body
- Vision loss
- Problems with speaking
- Confusion
- Sudden collapse
At SickKids
SickKids Neurosurgery Clinic – SickKids Neurosurgery offers the highest level of care to children with all types of neurosurgical disorders.
Paediatric Neurovascular Program – The Paediatric Neurovascular Program is made up of a team of specialists dedicated to providing care to children with neurovascular diseases.
Resources
Cavernous Malformation Canada – www.cavernousmalformation.ca
References
Smith ER. Cavernous Malformations of the Central Nervous System. N Engl J Med. 2024 Mar 14;390(11):1022-1028. Retrieved from: https://www.nejm.org/doi/10.1056/NEJMra2305116?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed.
Akers AL, et al. Guidelines for the Diagnosis and Clinical Management of Cavernous Malformations of the Brain and Spinal Cord: Consensus Recommendations Based on a Systematic Literature Review by the Alliance to Cure Cavernous Malformation Clinical Advisory Board Experts Panel. Neurosurgery. 2025 May 21;98(1):3–22. Retrieved from: https://pmc.ncbi.nlm.nih.gov/articles/PMC12680281/.