"No-no" type bobble-head doll syndrome in an infant with an arachnoid cyst of the posterior fossa: a case report.

Background: Bobble-head doll syndrome is a rare and surgically treatable movement disorder characterized by up-and-down (yes-yes) head bobbing occurring at a rate of 2-3 Hz. Side-to-side (no-no) head bobbing is less frequently described. Bobble-head doll syndrome is usually associated with dilation of the third ventricle, but is rarely associated with posterior fossa disease.