CausesBy Mayo Clinic staff
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|Chiari malformation type I|
Chiari malformation occurs when the section of the skull containing the cerebellum is too small or is deformed, thus putting pressure on and crowding the brain. The lowermost portion, or tonsils, of the cerebellum are displaced into the upper spinal canal. The pediatric form, Chiari II malformation, is always associated with a myelomeningocele. The adult form, Chiari I malformation, results primarily from a too small back portion of the skull.
When the cerebellum is pushed into the upper spinal canal, it can interfere with the normal flow of cerebrospinal fluid (CSF) that protects your brain and spinal cord. This impaired circulation of CSF can lead to the blockage of signals transmitted from your brain to your body, or to a buildup of spinal fluid in the brain or spinal cord. Alternatively, the pressure from the cerebellum upon the spinal cord or lower brainstem can cause neurological signs or symptoms.
- NINDS Chiari malformation information page. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/chiari/chiari.htm. Accessed Sept. 23, 2010.
- Chiari malformation. American Association of Neurological Surgeons. http://www.aans.org/Patient%20Information/Conditions%20and%20Treatments/Chiari%20Malformation.aspx. Accessed Sept. 24, 2010.
- Syringomyelia. American Syringomyelia and Chiari Alliance Project. http://www.asap.org/index.php/disorders/syringomyelia/. Accessed Sept. 24, 2010.
- Developmental diseases of the nervous system. In: Ropper AH, et al. Adams and Victor's Principles of Neurology. 9th ed. New York, N.Y.: The McGraw-Hill Companies; 2009. http://www.accessmedicine.com/content.aspx?aID=3637082. Accessed Sept. 24, 2010.