Upward herniation of the posterior fossa cyst in the shunted child.

Seventy-two years after Dandy and Blackfan's initial description of the Dandy-Walker syndrome, controversies still exist regarding the precise methods of treatment for this disorder. One potential complication of simple lateral ventricular shunting is upward herniation of the posterior fossa cyst, which at times can result in precipitous clinical deterioration. We present three examples of posterior fossa cysts with upward herniation and review the pertinent literature. We advocate contrast studies to determine whether aqueductal communication exists, before shunting is performed, as well as close follow-up of the shunted child.