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

Definition

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. There are four types of Chiari Syndrome, with different degrees of severity. Type 2 is the one that is associated with spina bifida.

Causes

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.

Risk Factors

The following conditions are commonly associated with Arnold-Chiari syndrome, but are not thought to be a cause of the disorder:

Symptoms

Symptoms exhibited 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

Diagnosis Your doctor will ask about symptoms and medical history, and perform a physical exam. He or she will also perform and MRI and/or CT scan to view the inside of the brain. Cerebrospinal fluid (CSF) is a vital fluid that surrounds the brain and spine. Special studies to evaluate the flow of CSF may be performed. Treatment Talk with your doctor about the best treatment plan. Treatment options include the following: Surgery 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. Prevention There is no known way to prevent Arnold-Chiari syndrome. Parents of a child with this condition may benefit from genetic counseling. RESOURCES: March of Dimes Birth Defects Foundation http://www.marchofdimes.com/ National Institute of Neurological Disorders and Stroke http://www.ninds.nih.gov CANADIAN RESOURCES: Canadian Neurological Sciences Federation
http://www.ccns.org/ Health Canada http://www.hc-sc.gc.ca/index_e.html References: 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 Childrens 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 April 2008 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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