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Arnold-Chiari Syndrome

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

    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.
  • Causes

    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
    GM00010 97870 brainstem.jpg
    Copyright © Nucleus Medical Media, Inc.
  • Risk Factors

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

    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
  • Diagnosis

    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

    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.
  • Prevention

    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.

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