What is chiari malformation?

Chiari malformation type i is neurological disorder where cerebellum (or more specifically the cerebellar tonsils), descends out of the skull into the spinal area, resulting in compression of parts of brain and spinal cord, and disrupts normal flow of cerebrospinal fluid.

Type ii involves extension of both cerebellar and brain stem tissue into the foramen magnum. Associated with myelomeningocele.