Chiari malformation and syringomyelia

Abstract

Chiari malformations are a group of abnormalities of the hindbrain that were originally described in 1891 by Hans Chiari, a German professor. His work, based on autopsy results, created the classic definitions of hindbrain herniation now described as Chiari type I (CIM), Chiari type II (CIIM), and Chiari type III (CIIIM) malformations. CIM consists of displacement of the cerebellar tonsils below the foramen magnum (FM). CIIM, usually associated with myelomeningocele (MM), includes caudal displacement of the inferior cerebellar vermis, the fourth ventricle, and the medulla into the cervical canal. CIIIM, a rare and severe form, includes a low occipital or high cervical encephalocele in combination with downward displacement of most of the cerebellum, the fourth ventricle, and possibly portions of the brainstem [3, 10, 19]. © 2007 Springer-Verlag Berlin Heidelberg.