Chiari malformation type I develops as the skull and brain are growing. As a result, signs and symptoms may not occur until late childhood or adulthood. The pediatric forms, Chiari malformation type II and type III, are present at birth (congenital). Treatment of Chiari malformation depends on the form, severity and associated symptoms. Chiari malformation type 1 (CM1) is a congenital anomaly of the cerebellum — the part of brain located at the base of the skull. In CM1, the tissue in the lower part of the cerebellum protrudes into the spinal canal, which can obstruct cerebrospinal fluid from flowing into the spinal canal.
Chiari malformations are structural defects in the base of the skull and cerebellum, the part of the brain that controls balance. Normally the cerebellum and parts of the brain stem sit above an opening in the skull that allows the spinal cord to pass through it (called the foramen magnum). When. Chiari malformation (CM) is a structural defect in the cerebellum, characterized by a downward displacement of one or both cerebellar tonsils through the foramen magnum (the opening at the base of the skull). CMs can cause headaches, difficulty swallowing, vomiting, dizziness, neck pain, unsteady gait, poor hand coordination, numbness and tingling of the hands and feet, and speech problems.Complications: Syringomyelia.