Chiari Malformation

Chiari malformation

On this MRI image, the white line shows where the opening in the base of the skull (foramen magnum) is. The arrow shows the bottom parts of the cerebellum (cerebellar tonsils) pushing down into the top of the spinal canal. Photo courtesy of the Chiari and Syringomyelia Foundation.

A Chiari malformation (key-AR-ee mal-for-MAY-shun) is a problem with the way parts of the brain are shaped and how they sit in the skull. In children with a Chiari malformation, parts of the brain hang down through the opening in the base of the skull (foramen magnum) into the upper neck.

Many children with a Chiari malformation do not have symptoms. But in more serious cases, the condition causes headaches, balance problems or damage to the brain or spinal cord.

In some families, more than 1 person has a Chiari malformation. But a specific genetic change (mutation) has not been found. Having 1 child with a Chiari malformation usually does not increase the chance of having another child with this condition. Your doctor can talk with you about the chance for your family.

  • There are a few types of Chiari malformations:

    • Chiari I malformation is most common. Parts of the cerebellum (cerebellar tonsils) hang down through the opening in the base of the skull into the upper neck. Most often, this happens while a baby is developing in the womb because the back of a baby’s skull is too small. The condition may be so mild that it does not cause symptoms until later in life.
    • Chiari II malformation: The bottom of the cerebellum (vermis) and parts of the brainstem hang down into the neck. This type also develops before birth. Children with this type also have a serious form of spina bifidacalled myelomeningocele.
    • Types III and IV are extremely rare.
    • Secondary (acquired) Chiari malformations: Sometimes a condition that increases pressure on the brain causes a Chiari malformation. For example, a brain tumor or increased fluid in the brain (hydrocephalus) can push the cerebellum down into the neck.
  • Sometimes a child with a Chiari malformation has another condition that affects their brain, spinal cord or spine. These include:

    • cyst filled with cerebrospinal fluid (CSF) in the spinal cord. This is called syringomyelia (se-ringo-my-EEL-e-ah). When parts of the brain come down into the neck, they may block the normal flow of CSF. Fluid may build up in the spinal cord and form a cyst that presses on your child’s brain and spinal cord.
    • Spina bifida, a birth defect that leaves the spinal cord open and unprotected because the bones of the spine do not close around the spinal cord as they should. All babies who have Chiari II malformations have spina bifida.
    • The spinal cord is pulled down and stuck in a child’s spinal canal (tethered spinal cord). The spinal cord might also pull the brain down. This is a rare cause of Chiari I malformations.
    • A curved spine (scoliosis) caused by a cyst. Most children with scoliosis do not have a Chiari malformation. But if they do, treating the Chiari malformation and the cyst may stop the scoliosis from getting worse or even improve it.

Chiari Malformation at Seattle Children’s

Consistently ranked one of the nation's best neurology and neurosurgery programs by U.S. News and World Report.Children from across the United States come to Seattle Children’s for treatment of Chiari malformations. Our goal is to help your child get back to normal life, free of headaches or other symptoms.

If you would like an appointment, ask your child’s primary care provider for a referral. If you have a referral, call 206-987-2016 to make an appointment.

If you have questions, please contact our Neurosciences Center at 206-987-2016.


    • Dr. Richard G. Ellenbogen serves on the scientific, education and advisory board of the nonprofit Chiari & Syringomyelia Foundation. He has treated more than 1,000 patients with Chiari malformation or syringomyelia.
    • Each year our neurosurgeons perform about 60 surgeries on children with this condition. We also evaluate many children with Chiari malformations who do not need surgery right away. We keep a careful watch as they grow and treat them as needed. Many never need surgery.
    • In our Neurodevelopmental Clinic, experts in many medical areas work together to care for children if a Chiari malformation causes problems in their thinking, balance, learning or emotions. We work with children throughout their childhood to help them reach their full potential.
    • Our first step in your child’s care is making an accurate diagnosis. For many children, this means having an MRI (magnetic resonance imaging) scan. Your child may also have a special MRI called a cine-MRI to see how CSFmoves in their brain.
    • Dr. Richard G. Ellenbogen helped develop guidelines for using cine-MRI to diagnose Chiari malformations and to care for children after surgery. Seattle Children’s has special computer software to make cine-MRI images. Our doctors are experienced in interpreting images from this type of MRI.
    • At Seattle Children’s, we will work with you to decide whether surgery, some other treatment or regular checkups are best for your child.
    • Children we treat have the option to take part in research studies of promising new treatments. These are called clinical trials. They can be especially important if your child’s condition is not well controlled with standard medicines or surgeries.
    • Dr. Ellenbogen studies the results of surgery for Chiari malformation in order to improve surgical treatment. He also uses MRI to better understand the flow of CSF around the brain and spinal cord.
    • Dr. Ghayda Mirzaa is one of the few researchers in the world looking into the way Chiari malformation happens. He studies brain tissue from children who have had surgery to learn how genes might affect the way the back of the brain develops.

    Learn more about Seattle Children’s research on Chiari malformation.

    • Children don’t react to illness, injury, pain and medicine in the same way as adults. They need – and deserve – care designed just for them. They need a healthcare team specially trained to understand and meet their needs.
    • Our doctors have special training in how to diagnose and treat children. They are focused on how today’s treatment will affect your child as they develop and become adults.
    • Our experts base their treatment plans on years of experience and the newest research on what works best – and most safely – for children and teens.
    • Learning that your child has a Chiari malformation can be stressful for the whole family. For children who need urgent treatment, Seattle Children’s is the only hospital in the region with coverage 24 hours a day, 7 days a week by a pediatric neurosurgeon.
    • During visits, we take time to explain your child’s condition. We help you fully understand your treatment options and make the choices that are best for your child.
    • Our doctors, nurses, child life specialists and social workers help your child and your family through the challenges of their condition. We connect you to community resources and support groups.
    • At Seattle Children’s, we work with many children and families from around the Northwest and beyond. Whether you live nearby or far away, we can help with financial counseling, schooling, housing, transportation, interpreter services and spiritual care. Read about our services for patients and families.

Symptoms of Chiari Malformation

Your child may not have symptoms. Symptoms are more likely if the malformation blocks the flow of cerebrospinal fluid (CSF) or puts pressure on the brain or spinal cord. Your child may have 1 or more of these:

  • Headaches in the back of the head or headaches that get worse with straining
  • Balance problems, which may cause trouble walking
  • Neck pain
  • Weakness
  • Numbness
  • Pain or tingling in their arms
  • Quick eye movements they can’t control, often from side to side (nystagmus)
  • Trouble with small motor tasks, such as writing or cutting with scissors
  • Swallowing problems or reduced gag reflex
  • Trouble breathing while asleep (sleep apnea)

Symptoms can happen at any time. They may start or get worse after an injury, physical effort or straining, such as exercising, coughing or sneezing.

  • Children with more serious forms of Chiari malformation will have the same symptoms as for Chiari I malformation. But the symptoms are usually worse and start sooner.

    Your child may have 1 or more of these:

    • A high-pitched sound when breathing in (stridor), mainly when crying (Chiari II)
    • Breathing tiny bits of food, fluid or saliva into the lungs (aspiration)
    • Arm weakness, numbness and tingling
    • Rarely, seizuresdevelopmental delays or other problems related to their nervous system

Diagnosing Chiari Malformation

Because a Chiari I malformation does not always cause symptoms, doctors may find it while they are checking your child for another reason. They may find it when your child has a CT (computed tomography) scan or MRI scan.

In babies with spina bifida, doctors do imaging studies shortly after birth and may find a Chiari malformation.

  • If doctors think your child might have a Chiari malformation, they will check your child’s:

    • Balance
    • Reflexes
    • Motor skills
    • Sense of touch
    • Memory
    • Thinking
  • Doctors use imaging studies called MRI (magnetic resonance imaging) scans to look for Chiari malformations. These scans of the head and spine let doctors see whether the bottom part of your child’s cerebellum or brainstem is coming down into the space where the spinal cord enters the spine (cervical spinal canal).

    The scans can also give doctors an idea of whether pressure is being put on your child’s cerebellum, brainstem or spinal cord. Often doctors order an MRI of the spine to check for syringomyelia, too.

    Your child’s doctors may use a test called a cine-MRI to see how CSF moves around the lower part of your child’s brain. This is also called a cine-MRI CSF flow study. It is a movie made from a series of MRIs. ("Cine" is pronounced SIN-nee, much like the word "cinema.")

    Cine-MRI helps doctors decide who may need surgery and which type would help most. Doctors also use it after surgery to tell how your child is doing.

Treating Chiari Malformations

A Chiari malformation that does not cause symptoms or affect your child’s daily life may not need any treatment. If your child does need treatment, our goal is help them get back to their life, without symptoms or limits on their usual physical activities. Together, you and your child’s doctor will decide whether your child needs treatment and which type is best for your child.

  • Medicine may help some symptoms. For example, pain medicines may help control headaches.

    Your child’s doctor may suggest avoiding certain activities, such as heavy lifting, that cause symptoms or make symptoms worse.

    Physical therapy or occupational therapy may help your child change how they do activities.

  • When deciding whether surgery might help your child, we consider:

    • What we find from your child’s MRI (magnetic resonance imaging).
    • Your child’s symptoms and whether they can be controlled with other treatment
    • If your child has numbness, weakness, loss of balance, vision changes or other signs of problems with their brain, spinal cord or nerves
    • If symptoms are getting worse
    • Whether your child has syringomyelia
    • Your family’s preference about whether to do surgery

    Your child’s doctor will talk with you in detail about the benefits and risks of surgery. Before surgery, your child may have imaging studies. These give the neurosurgeon more details about your child’s skull and neck. Doctors use the information to plan the best way to do surgery for your child. Options include:

    • X-ray
    • CT (computed tomography) scan
    • Another MRI scan
  • The most common surgery for Chiari malformations is called posterior fossa decompression. The procedure:

    • Makes more room in the skull for the cerebellum and brainstem. This relieves some pressure on the brain.
    • Lets cerebrospinal fluid (CSF) flow in a more normal way, which may relieve some symptoms.
    • In children with syringomyelia, lets the cyst drain so your child doesn’t need surgery on the cyst itself.

    Your child’s neurosurgeon will do 1 or more of these procedures:

    • Remove bone from the base of the skull. This makes the normal hole in the base of the skull (foramen magnum) bigger so there’s more room for the brain, spinal cord and CSF. Taking out the bone here is called suboccipital craniectomy.
    • Remove the back part of the first bone of the spine (first cervical vertebrae or C1). This makes more room for your child’s brain. This procedure is called C1 laminectomy. Some children who have surgery need only this procedure and suboccipital craniectomy.
    • Open the membrane over the brain. Where the bone was removed from the skull, the surgeon may open up the tough membrane that covers your child’s brain. This makes more room for CSF to flow. Only some children need this step.
    • Shrink the bottom parts of the cerebellum (cerebellar tonsils). With the membrane open, the surgeon may use a tool that is heated by an electric current (electrocautery) to shrink the cerebellar tonsils. This makes more room for CSF.
    • Patch the membrane using tissue from under your child’s scalp (pericranium). Other options include taking tissue from some other part of your child’s body or using a synthetic patch.
    • Close the incision. Finally, the neurosurgeon brings the skin back together.
  • After surgery, we will give your child medicine to help with pain and relax their muscles so they are comfortable while they heal. Often children do not remember much about this healing time. Most children stay in the hospital 1 to 3 days after surgery.

    If your child has a pericranial patch in the back of their head that is in contact with CSF, they might have swelling (inflammation) called aseptic meningitis. This reaction is not an infection. If needed, we will give your child corticosteroids to reduce the swelling.

    Follow-up care is important after surgery to watch for any symptoms that come back or get worse.

    In most children, symptoms of a Chiari malformation start to improve during the first month after surgery. Some children continue to have symptoms.

    For at least a few months while they heal, it is important for your child not to strain their neck. Your care team will let you know which activities your child should avoid, like heavy lifting and contact sports.

  • Sometimes children with Chiari malformation will need treatment for another condition that affects their brain, spinal cord or spine, such as:

    Children with these conditions will need regular checkups throughout life. Your doctor will look for new symptoms and check that any existing symptoms are not getting worse. Your child may benefit from these Seattle Children’s experts:

    • Our Neurodevelopmental team cares for children who have problems with learning, emotions or behavior. Doctors, nurses, social workers, dietitiansphysical therapists and occupational therapists work together to meet your child’s needs. We also help you find resources in your community.
    • Our Spine Program is known nationally for treating all kinds of spine problems in children.

Contact Us

If you would like an appointment, ask your child’s primary care provider for a referral. If you have a referral, call 206-987-2016.

Providers, see how to refer a patient.

If you have questions, contact us at 206-987-2016.