Magnetic resonance imaging of Chiari malformations

The authors describe the features of magnetic resonance (MR) images of Chiari type I and II malformations and present four illustrative cases. Downward displacement of the posterior fossa was more pronounced with type II than type I. A variety of intracranial anomalies were associated with the Chiari type II malformation, whereas type I was mainly associated with syringomyelia and craniovertebral changes. MR imaging is useful in the diagnosis of intracranial anomalies and those situated at the craniovertebral junction, including Chiari malformations.