Chiari malformations: anomalies of the cerebellum and brainstem, which is forced downwards into the spinal canal limiting the flow of cerebrospinal fluid. Associated with symptoms including dizziness, muscle weakness, headache, visual and co-ordination problems.
Chiari malformations are categorized into four types depending on the severity of the disorder and the parts of the brain displaced into the spinal canal.
Arnold-Chiari malformation (Type II Chiari malformation) associated with myelomeningocele
1883: Cleland was the first to describe Chiari II or Arnold–Chiari malformation on his report of a child with spina bifida, hydrocephalus, and anatomical alterations of the cerebellum and brainstem.
1891: Hans Chiari, a Viennese pathologist, described the case of a 17-year-old woman with ‘peg-like’ elongation of the cerebellar tonsils which are displaced downwards into the cervical canal. Not associated with hydrocephalus. This became known as Chiari malformation Type 1. Chiari also described the case of a 6-month-old with herniation of the lower cerebellum, pons and medulla and elongation of the 4th ventricle. The child also had hydrocephalus and myelomeningocele.
1894 Julius Arnold described his pathological post-mortem findings of an infant with herniation of the cerebellar tonsils and 4th ventricle through the foramen magnum. The infant also had spina bifida. The similarities between this and the findings of Hans Chiari lead to this being named the ‘Arnold-Chiari Malformation’. Alternatively known as Chiari malformation II. Arnold’s findings differed slightly as this infant did not have hydrocephalus, as Chiari’s initial Type 2 case.
1907: Schwalbe and Gredig, pupils of German pathologist Julius Arnold, described four cases of meningomyelocele and alterations in the brainstem and cerebellum, and gave the name “Arnold-Chiari” to these malformations.
1932: Van Houweninge Graftdijk was the first to report the surgical treatment of Chiari malformations. All patients died from surgery or postoperative complications.
1935: Russell and Donald suggested that decompression of the spinal cord at the foramen magnum might facilitate the CSF circulation.
1940: Gustafson and Oldberg diagnosed Chiari malformation with syringomyelia.
1974: Bloch et al. described the tonsils position to be classified between 7 mm and 8 mm below cerebellum.
1985: Aboulezz used MRI for discovery of extension
- Chiari malformation Type II
- Chiari H. Ueber Veränderungen des Kleinhirns infolge von Hydrocephalie des Grosshirns. Deutsche medizinische Wochenschrift 1891;17(42): 1172–1175
- Arnold. J. Myelocyste, Transposition von Gewebskeimen und Sympodie. Beiträge zur pathologischen Anatomie und zur allgemeinen Pathologie. 1894; 16: 1-28
- Schijman E. History, anatomic forms, and pathogenesis of Chiari I malformations. Childs Nerv Syst. 2004 May;20(5):323-8. [PMID 14762679]