Chiari Malformation Type I

The aim of this study is to analyze the association between a deformity of the cranial portion of the central spinal canal and syringomyelia in patients with a Chiari-type malformation of the craniocervical junction. The investigators hypothesize that Chiari malformation, defined by the herniation of the cerebellar tonsils through the foramen magnum, may be responsible for a deformation of the cranial portion of the central spinal canal, and that this deformation is associated with the presence of syringomyelia in patients with this malformation.