title: Neuroradiological diagnosis of Chiari malformations.
abstract: Chiari malformations 1, 2, 3 represent different degrees of herniation of posterior fossa content into the cervical canal (Chiari 1 and 2), or through an upper-cervical meningocele (Chiari 3), whereas Chiari 4 anomaly consists of hypoplasia of the cerebellum. Chiari 1 malformation (CM1) is the commonest anomaly; it is probably related to a mesodermal defect that create a congenitally small posterior fossa, subsequent overcrowding of its contents and herniation through the foramen magnum. The diagnosis of CM1 is based on the demonstration of the downward displacement and particular shape of the cerebellar tonsils into the upper cervical spinal canal associated with obliteration of the subarachnoid spaces at the level of the foramen magnum. MRI has a fundamental role in the correct identification of the anatomical aspects of this malformation and associated anomalies and represents the imaging modality of choice.
authors.affiliation: Department of Neuroradiology, Foundation IRCCS Neurological Institute Carlo Besta, Milan, Italy. lchiapparini@istituto-besta.it
authors.forename: Luisa
authors.initials: L
authors.lastname: Chiapparini
authors.forename: Veronica
authors.initials: V
authors.lastname: Saletti
authors.forename: Carlo Lazzaro
authors.initials: CL
authors.lastname: Solero
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Bruzzone
authors.forename: Laura Grazia
authors.initials: LG
authors.lastname: Valentini
mesh_terms: D001139:Arnold-Chiari Malformation / Q000145:classification / Q000175:diagnosis*; D001921:Brain / Q000002:abnormalities / Q000473:pathology*; D003388:Cranial Fossa, Posterior / Q000473:pathology; D006801:Humans; D059906:Neuroimaging / Q000379:methods*; D013115:Spinal Canal / Q000473:pathology*