Arnold-Chiari malformation

Chiari malformation is a pathology in which brain tissue extends into the spinal canal. This occurs when part of the skull is irregularly shaped or when it is smaller than normal. In this case, the skull exerts pressure on the brain and pushes it downward.
 
To correct it, surgery for Chiari malformation, also known as posterior fossa decompression surgery, aims to relieve pressure on the cerebellum and spinal cord. This is achieved by removing a section of bone from the back of the skull, which creates more space for the brain and allows cerebrospinal fluid to flow more freely.