The most common form of Chiari Malformation is Type 1, it often manifests later in
life (not at birth, but sometimes in
children) with headaches and cerebellar symptoms like dizziness and memory/concentration problems. The cerebellum in the lower back of the brain starts extending down past the skull into the spine. This herniation can, and often does, get worse. If you are diagnosed with Chiari 1, you generally will be told how far the herniation extends in millimeters.