title: Association of the Adult Chiari Malformation and Idiopathic Intracranial Hypertension: more than a coincidence.
abstract: There are significant similarities between the Adult Chiari Malformation (ACM) and Idiopathic Intracranial Hypertension (IIH). They include similar demographics, clinical presentation, and response to treatment. There is an eightfold increase in the incidence of significant tonsillar herniation in patients with IIH. Based on these findings and our observation in a subgroup of patients with failed ACM decompression, we suggest that these disorders are interrelated in a group of patients. The physiopathology is that of craniocephalic disproportion, i.e., a disproportion between the skull and the brain, due to a small skull or posterior fossa (like in ACM) and/or an engorged brain (like in IIH). This will occasionally lead to tonsillar ectopia. The craniocephalic disproportion will alter the brain compliance and lead to the symptomatology.
authors.affiliation: University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15213, USA. bejjanigk@msx.upmc.edu
authors.forename: Ghassan K
authors.initials: GK
authors.lastname: Bejjani
mesh_terms: D000818:Animals; D001139:Arnold-Chiari Malformation / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D019299:Decompression, Surgical; D003937:Diagnosis, Differential; D006801:Humans; D011559:Pseudotumor Cerebri / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D013223:Statistics as Topic; D013577:Syndrome