Chiari malformation is a common brain disorder where brain tissue extends into the spinal canal. It happens when part of the skull is abnormally small or misshapen and presses against the brain and forces it downward. It is usually categorized into three types depending on the anatomy of the brain tissue that is displaced into the spinal canal and if developmental abnormalities of the brain or spine are present. Chiari malformation type I develops as the skull and brain are growing. If a child has this condition he or she may not show any symptoms till late childhood or adulthood.