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

Spinal Defects

Not all causes of CM-I have been shown to be directly related to the posterior fossa and skull base. A few disorders, such as spondyloepiphyseal dysplasia,[18] caudal regression syndrome,[68,69] Klippel-Feil syndrome, atlantoaxial assimilation, basilar impression, and odontoid retroflexion (in which the vertebral column is the site of deformation) are also associated with CM-I. Little is known about the pathophysiology of these spinal deformities, but it is believed that difficulty in equilibrating the dynamic CSF pulse pressure induced by the Valsalva maneuver is responsible for the CM-I presentation.

Lipomeningomyelocele has also proven to be coupled with CM-I in as many as 3%–6% of patients.[2,4] It has been postulated that a decrease in intracranial nervous tissue and CSF due to the lipomeningomyelocele removes the expansile pressure of the brain on the skull, thus causing the posterior fossa to be smaller and less developed.[76]