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Chiari malformation

A Chiari malformation is a brain abnormality that affects the lower part of the brain, called the cerebellum. Many kids with this abnormality don't know they have the condition because they never have symptoms, and therefore aren't bothered by it.

But if your pediatrician suspects that your child has a Chiari malformation, or if your child has been diagnosed with the condition, the pediatric neurology team here at Cook Children's has the expertise and experience to determine what kind of treatments, including medicines and procedures, are available to help alleviate the symptoms of Chiari malformation, depending on his or her diagnosis.

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What is a Chiari malformation?

Chiari (pronounced key-are-ee) malformation is a brain abnormality that causes the cerebellum, the part of the brain that controls balance, coordination and muscle movement, to protrude into the space normally occupied by the spinal cord. Some children are born with the condition, and others develop it as they grow

Chiari malformation causes pressure on the cerebellum, brain stem, and spinal cord that can keep them from working correctly. It can also block the movement of cerebrospinal fluid, the liquid that surrounds the brain and spinal cord and protects them from injury. When cerebrospinal fluid doesn't flow properly, it can build up in the brain and spinal cord and block communication of the brain's messages to the body.

Normally the cerebellum and parts of the brain stem sit in an indented space at the lower rear of the skull, above the foramen magnum (a funnel-like opening to the spinal canal). When part of the cerebellum is located below the foramen magnum, it is called a Chiari malformation.

Chiari malformations may develop when the bony space is smaller than normal, causing the cerebellum and brain stem to be pushed downward into the foramen magnum and into the upper spinal canal. The resulting pressure on the cerebellum and brain stem may affect functions controlled by these areas and block the flow of cerebrospinal fluid — the clear liquid that surrounds and cushions the brain and spinal cord — to and from the brain.

What causes Chiari malformations?

Most cases of Chiari malformations are congenital, which means that a child developed it in the womb and had it at birth. This is called primary or congenital Chiari malformation. In these cases, structural defects in the brain and spinal cord occur during fetal development, such as when the space at the back of the skull, where the cerebellum sits above the spine, is too small or is unusually shaped. These "cramped quarters" squeeze the cerebellum and even part of the brain stem, which controls the nerves in the face and neck, down through the foramen magnum (a funnel-like hole below the skull through which only the spinal cord usually passes). These congenital Chiari malformations may be due to a genetic mutation. They may also be related to a lack of proper vitamins or nutrients in the maternal diet.

Although doctors haven't been able to identify a gene that causes Chiari malformation, it does sometimes run in families, which indicates that it could be hereditary.

Chiari malformation can also be caused later in life if spinal fluid is drained excessively from the lumbar or thoracic areas of the spine either due to injury, exposure to harmful substances or infection. This is called acquired or secondary Chiari malformation. Primary Chiari malformation is much more common than secondary Chiari malformation.

There are four different types of Chiari malformation (I, II, III, and IV). Type I is by far the most common in children. Chiari malformations are classified by the severity of the disorder and the parts of the brain that protrude into the spinal canal and are as follows:

What are the symptoms of a Chiari malformation?

Many kids with type I Chiari malformation have no signs and symptoms and don't even know that they have a malformation. They find out about it only when they're tested for another problem.

But if a Chiari malformation is severe enough to block the flow of cerebrospinal fluid or put significant pressure on the brain or spinal cord, a child's nervous system can be affected. Symptoms can include dizziness and problems with balance and coordination. This means a child might fall down a lot, walk unusually, have trouble grasping items, or have poor hand-eye coordination.

Other symptoms can include:

Signs of Chiari malformation in babies include:

Some children with Chiari malformations also have cognitive and behavioral problems. Doctors aren't sure whether a Chiari malformation directly causes these problems or whether they're simply the child's way of reacting to the condition and its symptoms.

Since the symptoms of Chiari malformations vary greatly and may mimic many other conditions, it's important to get an accurate diagnosis. If your child has already been diagnosed and you feel unsure about your child's diagnosis, the neurology team at Cook Children’s is happy to provide a second opinion.

Are other conditions associated with Chiari malformations?

Individuals who have a Chiari malformation often have these related conditions:

How common are Chiari malformations?

In the past, it was estimated that the condition occurs in about one in every 1,000 births. However, the increased use of diagnostic imaging has shown that Chiari malformation may be much more common. Complicating this estimation is the fact that some children who are born with the condition may not show symptoms until adolescence or adulthood, if at all. Chiari malformations occur more often in women than in men and Type II malformations are more prevalent in certain groups, including people of Celtic descent.

How are Chiari malformations diagnosed?

Many people with Chiari malformations have no symptoms and their malformations are discovered only during the course of diagnosis or treatment for another disorder.

If your doctor suspects a Chiari malformation, your child will be carefully examined and tested for things like speech, memory, cognition, balance, touch, reflexes, sensation, and motor skills. In addition, your doctor will probably want your child to undergo one or more of these tests:

How are they treated?

"Right now, surgery is the only treatment option for clinically symptomatic Chiari malformations. Our process for the surgery requires a greater amount of time, but the protocols we've implemented have radically changed the level of safety available."

John Honeycutt, M.D.
Medical Director, Neurosurgery
Medical Director, Neuro-Trauma
Co-director of the Jane and John Justin Neurosciences Center

There is no cure for Chiari malformation. However, most children who don't have symptoms won't require treatment. If your child does have Chiari malformation but doesn't have any symptoms, he or should continue to see their doctors for regular checkups to make sure that their condition doesn't change.

When symptoms do occur, treatment will focus on relieving them and stopping further damage to the brain and spinal cord (for example, medications may be used to ease symptoms like headaches and neck pain). And sometimes the doctor will recommend limiting activities that worsen symptoms.

For severe symptoms, surgery is the only treatment available to correct functional disturbances or halt the progression of damage to the central nervous system. If your child is referred for surgery, you will meet with the surgeon and your neurology team to determine the best plan of action for your child.

A common procedure for kids with Chiari malformation is decompression. It helps to relieve pressure on the brain and spinal cord, restore the flow of cerebrospinal fluid, and prevent additional damage. This surgery usually takes several hours and involves removing part of the skull and a portion of the spine's top vertebra.

Another surgical option involves implanting a shunt or tube to help drain cerebrospinal fluid and relieve pressure on the brain. Shunts are commonly used to help children who have hydrocephalus or syringomyelia.

Infants and children with myelomeningocele may require surgery to reposition the spinal cord and close the opening in the back.

While surgery is not a cure for Chiari malformations, in certain cases it can provide relief and help to restore your child’s ability to do the everyday things that kids do, like run, jump, play, read, write and share special moments with family and friends. In other words, enjoy childhood as much as possible.

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If your child has been diagnosed, you probably have lots of questions. Call our offices at: 682-885-2500 to schedule an appointment, refer a patient or speak to our staff.

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