About Chiari Malformation
If you look at the inside view of a skull, you will see many grooves and holes that fit the brain perfectly and allow nerves and blood vessels to pass through. The brain and skull develop together, allowing for maximum protection and ideal function.
A Chiari malformation is a problem with one of these grooves, where a part of the brain called the cerebellum fits. The space in the bone is too small to accommodate the cerebellum, a problem that is typically developmental in Type 1 Chiari malformation. As a result, the cerebellum is displaced down through a hole at the bottom of the skull, the foramen magnum.
The foramen magnum is the passageway for the spinal cord, which is cushioned by a liquid called cerebrospinal fluid (CSF). If the passageway is blocked, as it is by the cerebellum in a Chiari malformation, there can be a buildup of CSF, as well as excessive pressure on the brain stem and/or spinal cord.