What is Chiari I Malformation?

The Chiari I malformation is a congenital malformation in which the back compartment of the skull is formed too small and results in crowding of neurological tissues. The lower part of the cerebellum, called the cerebellar tonsils, hangs down through the opening at the bottom of the skull and causes blockage of spinal fluid to the spinal canal. This crowding and blockage often brings on neurological symptoms including headache, dizziness, blurred vision, and many others.