Chiari I Malformation
en español: Anomalía de Arnold Chiari tipo I
Medically reviewed by: Amy W. Anzilotti, MD
What Is Chiari I Malformation?
Chiari I malformation (key-AR-ee mal-fore-MAY-shun) is when the cerebellum — the part of the brain that controls coordination and muscle movement — pushes down through the hole in the bottom of the skull. This hole is called the foramen (feh-RAY-men) magnum. Usually just the spinal cord passes through the foramen magnum.