(Arnold-Chiari Malformation; Type II Chiari Malformation; Cerebellomedullary Malformation Syndrome)
Arnold-Chiari syndrome is a defect in the formation of the cerebellum (the small, bottom portion of the brain) and brainstem. This defect can prevent the passage of blood from the brain into the spinal canal. Arnold-Chiari syndrome is usually accompanied by a myelomeningocele, which is a form of spina bifida
Brain Stem and Cerebellum
Arnold-Chiari syndrome occurs during brain development before birth. The indented bony space in the lower rear of the skull is smaller than normal, so the cerebellum and brainstem are pushed downward. The reason the brain does not develop normally is not well understood.
The following conditions are commonly associated with Arnold-Chiari syndrome, but are not thought to be a cause of the disorder:
- Spina bifida
Symptoms exhibited in infants may include:
- Mental impairment
- Paralysis of the limbs
Symptoms in adolescents are usually milder and may include:
- Weakness of the legs
Your doctor will ask about symptoms and medical history, and perform a physical exam. He or she will also perform and MRI
Cerebrospinal fluid (CSF) is a vital fluid that surrounds the brain and spine. Special studies to evaluate the flow of CSF may be performed.
Talk with your doctor about the best treatment plan. Treatment options include the following:
Surgery is usually required to correct any obstruction in the brain.
Treatment of Symptoms
Depending on the symptoms associated with Arnold-Chiari syndrome, other treatments may be beneficial. For instance, physical or occupational therapy can help improve muscular coordination and trembling. In addition, braces or a wheelchair may be needed. Speech therapy may also be beneficial.
March of Dimes Birth Defects Foundation
National Institute of Neurological Disorders and Stroke
Canadian Neurological Sciences Federation
Arnold-Chiari malformation. DynaMed website. Available at: http://dynamed102.ebscohost.com/Detail.aspx?id=115525 . Accessed May 23, 2007.
Arnold-Chiari syndrome. Arkansas Spinal Cord Commission website. Available at: http://www.spinalcord.ar.gov/Publications/FactSheetsPDF/ArnoldChiari.pdf . Accessed May 23, 2007.
Chiari malformation. Comer Children’s Hospital University of Chicago at: http://www.uchicagokidshospital.org/online-library/content=P02592 .
Chiari malformation information page. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/disorders/chiari/chiari.htm . Accessed May 23, 2007.
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.
Last reviewed November 2008 by
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