• Arnold-Chiari Syndrome

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


    Arnold-Chiari syndrome is a series of nervous system symptoms. The symptoms can be different for each person but may include dizziness, paralysis of limbs, numbness, headaches, and problems with balance or coordination.
    This condition is often present at birth but can also develop later in life. Some people with very 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 you head. The rear lower part of the brain and the brainstem sit 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 brainstem are pushed downward. This position can block the flow of fluid to the brain and spine.
    The problem with the skull develops before birth. It is not clear why it happens. In some cases, it is accompanied by a myelomeningocele, which is a form of spina bifida .
    Brain Stem and Lower Brain
    GM00010 97870 brainstem.jpg
    Copyright © Nucleus Medical Media, Inc.

    Risk Factors

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


    People with Arnold-Chiari syndrome may also have:
    Symptoms in infants may include:
    • Vomiting
    • Mental impairment
    • Weakness
    • Paralysis of the limbs
    Symptoms in adolescents are usually milder and may include:
    • Dizziness
    • Fainting
    • Weakness of the legs
    • Headaches
    • Double vision
    • Deafness
    • Swelling of the optic nerve region
    • Rapid eye movement
    • Lack of muscular coordination
    • Uncontrolled shaking or trembling
    • Walking problems
    • Numbness or tingling in the extremities


    Your doctor will ask about symptoms and medical history. A physical exam will be done. Your doctor may also need detailed images of the brain and skull. The pictures may be taken with:
    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. For example:
    • Physical or occupational therapy can help improve muscular coordination and trembling. Braces or a wheelchair may be needed.
    • Speech therapy for speech or swallowing problems.
    • Medication to help manage headaches.
    The malformation may also block the flow of fluid in the brain and spine. Surgery may be needed to correct the flow of fluid.
    Talk with your doctor about the best treatment plan.


    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.


    March of Dimes Birth Defects Foundation http://www.marchofdimes.com/

    National Institute of Neurological Disorders and Stroke http://www.ninds.nih.gov/


    Canadian Neurological Sciences Federation http://www.ccns.org/

    Health Canada http://www.hc-sc.gc.ca/index%5Fe.html


    Arnold-Chiari malformation. DynaMed website. Available at: http://dynamed102.ebscohost.com/Detail.aspx?id=115525 . Updated March 12, 2012. Accessed September 18, 2012.

    Chiari malformation. Comer Children’s Hospital University of Chicago at: http://www.uchicagokidshospital.org/online-library/content=P02592 . Accessed July 31, 2012.

    Chiari malformation information page. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/disorders/chiari/chiari.htm . Updated February 1, 2012. Accessed September 18, 2012.

    Kinsman SL. Chiari malformation. In: Gilman S, ed. MedLink Neurology. San Diego, CA: MedLink Corporation. Available at: http://www.medlink.com . Accessed August 10, 2007.

    Revision Information

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