Overview

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

Chiari malformation is uncommon, but increased use of imaging tests has 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 problems of the brain or spine are present.

Chiari malformation type 1 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 2 and type 3, 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.