Chiari malformations are problems with the structures at the back of the brain. A part of the brain called the cerebellum normally sits inside the back of the skull. This problem causes it to sit partially or fully below the skull. This can put pressure on the cerebellum, brainstem, and spinal cord. It can also block the flow of cerebrospinal fluid (CSF) and cause pressure around the brain and spinal cord.
There are four types:
Type 1 is often found in older children and young adults (most common)
Type 2 is a more severe form of Type 1 that is often found at birth in children with spina bifida
Type 3 is a rare form that is found at birth and causes severe problems with the nervous system
Type 4 is a rare form that happens when the cerebellum has not developed the right way
Chiari malformation is most often caused by a problem in the way the skull forms before birth. It is not known why this happens. Genes may play a role.
Chiari malformation. American Association of Neurological Surgeons website. Available at: https://www.aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Chiari-Malformation. Accessed April 7, 2020.
Chiari malformation. Columbia University Medical Center website. Available at: http://www.columbianeurosurgery.org/conditions/chiari-malformation. Accessed April 7, 2020.
Chiari malformation fact sheet. National Institute of Neurological Disorders and Stroke website. Available at: https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Chiari-Malformation-Fact-Sheet. Updated March 13, 2020. Accessed April 7, 2020.
Last reviewed February 2020 by
EBSCO Medical Review Board
Rimas Lukas, MD
Last Updated: 4/7/2020
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