Summary: Declares the month of September 2023 as Chiari Malformation Awareness Month. Chiari Malformation is a serious neurological disorder affecting more than 300,000 people in the United States. Chiari Malformation was first identified by Austrian pathologist Professor Hans Chiari in the 1890s and categorized into four types in order of severity. Chiari Malformation is a congenital malformation in which the bottom of the brain, known as the cerebellum, is crowded in the skull cavity and forces the lower tips of the cerebellar hemispheres, or tonsils, into the hole in the bottom of the skull, or foramen magnum.