Pediatric Radiology > Neurological > Developmental Abnormalities > Chiari II

Chiari II

Type II Chiari malformations are almost always associated with myelomeningoceles, and almost all patients with myelomeningocele have Chiari II. There is typically hydrocephalus. The posterior fossa is small with inferior displacement of the cerebellum, medulla, and fourth ventricle into the upper cervical canal. Other imaging findings are a kinked medulla, colpocephaly (enlargement of the posterior body of the lateral ventricles), enlarged massa intermedia, inferior pointing of the lateral ventricles, and tectal beaking.

Chiari II  
A lacunar skull is often present in the first year of life representing a dysplasia of bone that disappears by the end of the first year of life with or without the treatment of the hydrocephalus. The skull appears scalloped representing bony septations of the dysplasia.
AP and lateral views of a lacunar skull

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