What is a Chiari malformation?
A Chiari malformation is a problem in which a part of the brain at the rear of the skull bulges through a normal opening (foramen magnum) 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).
There are several types of Chiari malformations, but type I (CM-I) is the most common type. In type I, part of the cerebellum bulges through the foramen magnum. This type is most often congenital (also called primary CM-I), but is often not found until a child is a teen or young adult. In rare cases, this type may also develop later in life. This is known as acquired or secondary CM-I.
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 with genetic problems that run in families.
An acquired Chiari malformation type I happens to a person after birth. It is caused by excess leaking of spinal fluid 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.
What are the symptoms of a Chiari malformation type I?
Your child may not have any symptoms. Or symptoms may develop slowly over time. Most children don't have symptoms until they are teens or young adults.
The most common symptoms are headaches or pain in the back of the head or neck. The headaches and pain are made worse by coughing, laughing, or sneezing.
Your child may also have other symptoms of a Chiari malformation type I, such as:
Hoarseness or trouble speaking
Rapid, back and forth eye movements (nystagmus)
Periods of not breathing during sleep (sleep apnea)
Weakness or abnormal movements
Trouble with balance
Abnormal shape of the spine (scoliosis)
Your child may also have a pocket of fluid in the spinal cord or brain stem. This is called a syrinx. A syrinx can cause trouble walking or pain in the arms or legs.
How is a Chiari malformation type I diagnosed?
In a child with no symptoms, the defect may be found when imaging tests are done for other reasons. For a child with symptoms, the health care provider will ask about your child's medical history and give your child a physical exam. He or she may refer your child 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.
How is a Chiari malformation type I treated?
Your child may be treated by neurologists and neurosurgeons. These are experts in brain and spinal cord problems. Treatment will depend on your child’s symptoms, age, and general health. It will also depend on how severe the condition is.
With no symptoms. Your child’s health may be watched closely. This may include frequent physical exams and MRI tests.
With symptoms. Your child's health care provider may prescribe medicines to reduce pain. Or he or she may advise decompression surgery. This is done to relieve pressure on the brain, or to restore the flow of spinal fluid.
With few or no symptoms, but a syrinx. Your child's health care provider may suggest close monitoring of the defect with a special type of MRI called cine phase contrast. This helps look for blocked spinal fluid flow. Your child may need surgery, based on the MRI results or if symptoms get worse.
With signs of sleep apnea. Your child may need a sleep study. In this test, your child will be monitored during sleep to look for problems. A sleep study can also help the health care provider decide on additional treatment.
What are the complications of a Chiari malformation type I?
Complications of a Chiari malformation type I can include:
Development of syrinx
Permanent damage to muscles or nerves
Carefully watching for changes in your child’s health can help prevent complications. This helps to make sure that treatment is done early.
How is a Chiari malformation type I managed?
It is hard for health care providers to predict how a Chiari malformation type I will affect a child’s long-term health. Your child may not have any changes caused by the defect. Or he or she may have worsening neurological problems. Your child’s health will be closely watched. This will include with frequent physical exams and imaging tests such as MRI. There is ongoing research as to how to best manage Chiari malformations.
When should I call my child's health care provider?
Call your child's health care provider if you notice any changes in your child. Be sure to call if you notice problems with:
Walking or moving
Key points about Chiari malformation type I
With a Chiari malformation, the lower part of the brain dips down through a normal opening at the bottom of the skull. In some cases, more brain tissue also dips down through this opening.
In most cases, the problem is present at birth (congenital).
There are several types of Chiari malformations. Type I is the most common type.
Your child may not have symptoms. If symptoms occur, the most common ones are headaches or pain in the back of the head or neck. The headaches and pain are made worse by coughing, laughing, or sneezing.
Your child may also have a pocket of fluid in the spinal cord or brain stem. This is called a syrinx.
Imaging tests are done to detect a Chiari malformation type I. Your child may have an MRI or a CT scan.