Associated Disorders of Chiari Type I Malformations

A Review

Marios Loukas, M.D., Ph.D.; Brian J. Shayota, B.S.; Kim Oelhafen, B.S.; Joseph H. Mill er, M.D.; Joshua J. Chern, M.D., Ph.D.; R. Shane Tubbs, M.S., P.A.-C., Ph.D.; W. Jerry Oakes, M.D.


Neurosurg Focus. 2011;31(3):e3 

In This Article


When hyperostosis affects the posterior fossa, it can often lead to CM-I. Paget disease of the skull is one example in which exaggerated bone turnover leads to thickening and deformation of bones. When this process takes place in the skull, it can compromise the posterior fossa and in a few cases has been reported to result in CM-I. Both Iglesias-Osma et al.[23] and Richards et al.[53] have described cases of this association but few others have been reported.

Cases of CM-I relating to craniometaphyseal dysplasia are also exceedingly rare, but have nonetheless been noted in the past. Craniometaphyseal dysplasia, similar to the other types of hyperostosis, can manifest with CM-I due to abnormal bone formation and progressive thickening. Of the few cases, Sewell and colleagues[61] documented cervicomedullary compression as well. Chiari Type I malformation secondary to osteopetrosis[26] and erythroid hyperplasia[51] have been documented but are also considered to be exceptionally rare.