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Arnold-Chiari Syndrome(Arnold-Chiari Malformation; Type II Chiari Malformation; Cerebellomedullary Malformation Syndrome)

Arnold-Chiari syndrome is a series of nervous system symptoms related to a deformity of the skull.

This condition is often present at birth, but can also develop later in life. Some people with mild forms of this syndrome may never know they have the condition. For others it can be more severe. These severe forms will need treatment.


Arnold-Chiari syndrome is caused by a problem in the back of the skull. The skull should have an indented space in the back of the head. The rear lower part of the brain and the brainstem are in this space. In some people, this indented skull space does not develop well. This is called Chiari malformation. The space inside the skull is too small for the brain. As a result, the brain and brain stem are pushed downward. It blocks the flow of fluid from the brain to the spinal column.

The problem with the skull develops before birth. It is not clear why it happens. In some cases, it occurs with a myelomeningocele, which is a form of spina bifida or syringomyelia, which is fluid cavites in the spinal cord.

Brain Stem and Lower Brain


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Risk Factors

There are no known risk factors for Chiari malformation. There may be a genetic connection in some families.


Symptoms in infants are due to pressure on the lower part of the brain and brainstem. They may include:

  • Vomiting
  • Weakness
  • Paralysis of the limbs
  • Choking
  • Chronic cough or hoarseness

Symptoms in adolescents are usually milder and may include:

  • Lightheadedness
  • Fainting
  • Weakness in the legs
  • Headaches
  • Inability to hear or ringing in the ears
  • Eye problems such as difficulty seeing, eye pain, and rapid eye movement
  • Poor coordination
  • Uncontrolled shaking or trembling
  • Difficulty walking
  • Numbness or tingling in the arms or legs

You will be asked about symptoms and medical history. A physical exam will be done. Imaging tests evaluate the brain and skull. These may include:

Special studies may also be done to evaluate the flow of fluid around your brain and spinal cord.


Treatment will be based on individual symptoms and the degree of pressure on the brain. For example:

  • Physical or occupational therapy can help improve muscular coordination and trembling. Braces or a wheelchair may also be needed.
  • Speech therapy for speech or swallowing problems.
  • Medication to help manage headaches and pain.
  • The malformation may also block the flow of fluid in the brain and spine. Surgery may be needed to correct the flow of fluid.
  • Surgery may also be done to release compression of the brain.

Talk with your doctor about the best treatment plan for you.


There is no known way to prevent Arnold-Chiari syndrome. Genetic counseling may help parents of a child with this condition to determine the risk in future children.


American Syringomyelia and Chiari Alliance Project

National Institute of Neurological Disorders and Stroke


Canadian Neurological Sciences Federation

Health Canada


Chiari malformation. Comer Children’s Hospital website. Available at: Accessed February 12, 2014.

Chiari malformations. EBSCO DynaMed website. Available at: Updated March 12, 2012. Accessed February 12, 2014.

Chiari malformation information page. National Institute of Neurological Disorders and Stroke website. Available at: Updated December 30, 2013. Accessed February 12, 2014.

Hekman KE, Aliaga L, et al. Positive and negative predictors for good outcome after decompressive surgery for Chiari malformation type 1 as scored on the Chicago Chiari Outcome Scale. Nuerol Res. 2012;34(7):694-700.

Last reviewed January 2015 by Rimas Lukas, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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