Dandy–Walker syndrome (DWS) is a rare group of congenital human brain malformations. There are three subtypes which affect multiple organs to varying degrees, but the fundamental abnormalities involve the cerebellum which controls muscle coordination. The adjacent fourth ventricle is often affected which can alter the flow of cerebrospinal fluid, increase intracranial pressure, and lead to multiple other brain function problems. The degree of disability varies but is typically lifelong. Treatment may involve physical therapy, special education, or surgical placement of a cerebral shunt. It is named for Walter Dandy and Arthur Earl Walker.