Chiari Decompression

The exact cause of a congenital Chiari malformation type I is not known. A problem during fetal growth may cause the defect.

A Chiari malformation is a problem in which a part of the brain (the cerebellum) at the back of the skull bulges through a normal opening in the skull where it joins the spinal canal.

This puts pressure on parts of the brain and spinal cord and can cause mild to severe symptoms. In most cases, the problem is present at birth (congenital). By Chiari decompression, the bones at the back of the skull are removed to create more brain space and widen the foramen magnum.

This surgery can address symptoms such as headache, hydrocephalus, sleep apnea, and others.

Main Types of Chiari Malformation

There are several Chiari malformations, but type I is the most common. In type I, the cerebellum bulges through the normal opening at the base of the skull.

This type is most often congenital. It is also called primary Chiari malformation type I. But it is often only found once a person is a teen or young adult.

In rare cases, this type may also develop later in life. This is known as acquired or secondary Chiari malformation type I.

Type 1 Chiari malformation symptoms and signs can show up in infants, children, teens, or adults.

Type 2 Chiari malformation is associated with spina bifida and is present at birth.

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    Signs and Symptoms of Chiari Malformations


    Chiari malformations are associated with forming a syrinx, a fluid-filled pocket or cyst, in the spinal cord. This condition is also known as syringomyelia. As the cyst fills with cerebrospinal fluid, it expands, putting pressure on the spinal cord.

    In some patients with a Chiari malformation, increasing pressure from a syrinx can affect neuromuscular function, causing limb weakness or difficulties with walking or breathing.

    Some children will show signs of a spine syrinx, but others will not. An MRI scan may be needed for a definite diagnosis in these situations.



    In children younger than 16 whose spines are still growing, the presence of a syrinx can also be associated with the development of scoliosis, an abnormal lateral (side-to-side) curvature of the spine.

    Toddlers, children, and teens with undiagnosed type 1 Chiari malformations may develop headaches, typically located at the back of the head and neck and often made worse by exertion.


    Type 2 Chiari malformations can also be associated with hydrocephalus, a condition in which there is an obstruction of the flow of cerebrospinal fluid that is found inside the ventricles (fluid-filled areas) inside the brain.

    The fluid buildup causes the pressure inside the head to increase, and the child’s skull bones expand to a larger-than-normal appearance.

    Sleep Apnea

    Sleep apnea is another problem that occurs in people with a Chiari malformation. This is a serious sleep disorder characterized by brief interruptions in breathing during sleep. A sleep study can confirm the presence of sleep apnea so a doctor can prescribe treatment.

    Other Symptoms may include:

    • Rapid, side-to-side eye movements (nystagmus)

    • Muscle weakness, lack of balance, or abnormal reflexes

    • Nerve problems, including paralysis

    • Hoarseness

    • Difficulty swallowing

    Frequently Asked Questions about
    Chiari Malformations & Chiari Decompression

    What Causes a Chiari Malformation Type I?

    The exact cause of a congenital Chiari malformation type I is not known. A problem during fetal growth may cause the defect. It may be caused by contact with harmful substances during pregnancy. Or it may be linked to genetic problems that run in families.

    An acquired Chiari malformation type I happens to a person after birth. It is caused by excess spinal fluid leaking from the lower back (lumbar) or chest (thoracic) areas of the spine. This can happen because of an injury, contact with harmful substances, or an infection.

    How Is a Chiari Malformation Type I Diagnosed?

    If you have no symptoms, the problem may be found when you have imaging tests for other reasons. If you have symptoms, your healthcare provider will ask about your health history and give you a physical exam. They may refer you to a specialist.

    Imaging tests are done to detect a Chiari malformation type I. Your child may have 1 or more of these tests:

    • MRI. This test is the one most often used to diagnose Chiari malformations. It uses large magnets and a computer to make detailed pictures of the inside of the body.
    • CT scan. This test uses a series of X-rays and a computer to create detailed pictures of the inside of the body. A CT scan is more detailed than a regular X-ray.

    Dr. Abdul Baker has been performing Chiari decompression at his Sherman and Plano offices for over a decade.

    How Is Chiari Malformation Type I Treated?

    A neurologist or neurosurgeon may treat you. These are experts in brain and spinal cord problems. Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.

    • With no symptoms: Your health may be watched closely. This may include frequent physical exams and MRI tests.
    • With symptoms: Your healthcare provider may prescribe medicines to reduce pain. Or he or she may choose surgery. This is done to relieve pressure on the brain or restore spinal fluid flow.
    • With few or no symptoms but a syrinx: Your healthcare provider may suggest close monitoring of the defect with a special type of MRI called cine phase contrast. This test looks at the flow of spinal fluid. It also looks at areas where the fluid is blocked. You may need surgery, based on the MRI results, or if symptoms get worse.
    • With signs of sleep apnea: You may need a sleep study if you have sleep apnea. Sleep apnea means that you stop and start breathing during sleep. A sleep study can also help your healthcare provider decide if you need other treatment.

    What Are Other Health Problems Caused By a Chiari Malformation Type I?

    These health problems can include:

    • Long-term pain
    • A pocket of spinal fluid (syrinx) in the spinal cord or brain stem. This forms over time.
    • Life-long damage to muscles or nerves
    • Not being able to move your arms or legs because the muscles no longer work (paralysis)

    Carefully watching for changes in your health can help prevent these problems. This helps to make sure that treatment is done early.

    When Should I Call My Healthcare Provider?

    Call your healthcare provider if you notice any changes. Be sure to call if you notice problems with the following:

    • Breathing
    • Swallowing
    • Feeding
    • Speaking
    • Walking or moving
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