Chiari malformation (kee-AH-ree mal-for-MAY-shun) is a condition in which brain tissue extends into your spinal canal. It occurs when part of your skull is abnormally small or misshapen, pressing on your brain and forcing it downward.

Chiari malformation is uncommon, but increased use of imaging tests have led to more frequent diagnoses.

Doctors categorize Chiari malformation into three types, depending on the anatomy of the brain tissue that is displaced into the spinal canal, and whether developmental abnormalities of the brain or spine are present.

Chiari malformation type I develops as the skull and brain are growing. As a result, signs and symptoms may not occur until late childhood or adulthood. The pediatric forms, Chiari malformation type II and type III, are present at birth (congenital).

Treatment of Chiari malformation depends on the form, severity and associated symptoms. Regular monitoring, medications and surgery are treatment options. In some cases, no treatment is needed.

Chiari malformation care at Mayo Clinic

Sept. 29, 2016
  1. Chiari malformation fact sheet. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/chiari/detail_chiari.htm. Accessed July 19, 2016.
  2. Tubbs RS, et al. The Chiari malformations and syringohydromyelia. In: Principles of Neurological Surgery. 3rd ed. Philadelphia, Pa.: Saunders Elsevier; 2012. http://www.clinicalkey.com. Accessed July 19, 2016.
  3. Khoury C. Chiari malformations. http://www.uptodate.com/home. Accessed July 19, 2016.
  4. Ropper AH, et al. Developmental diseases of the nervous system. In: Adams & Victor's Principles of Neurology. 10th ed. New York, N.Y.: The McGraw-Hill Companies; 2014. http://www.accessmedicine.com. Accessed July 19, 2016.
  5. Chiari malformation. American Association of Neurological Surgeons. http://www.aans.org/Patient%20Information/Conditions%20and%20Treatments/Chiari%20Malformation.aspx. Accessed July 19, 2016.
  6. Tubbs RS, et al. Chiari malformations. In: Youmans Neurological Surgery. 6th ed. Philadelphia, Pa.: Saunders Elsevier; 2011. http://www.clinicalkey.com. Accessed July 19, 2016.
  7. Heiss J, et al. Management of Chiari malformations and syringomyelia. In: Schmidek and Sweet's Operative Neurosurgical Techniques. 6th ed. Philadelphia, Pa.: Saunders Elsevier; 2012. http://www.clinicalkey.com. Accessed July 19, 2016.
  8. Riggin EA. Decision Support System. Mayo Clinic, Rochester, Minn. May 10, 2016.