An unusual presentation of bobble-head doll syndrome in a patient with hydranencephaly and Chiari 3 malformation.

Bobble-head doll syndrome is a rare movement disorder that is usually associated with lesions involving the third ventricle. It is characterised by stereotypical rhythmic up-and-down or side-to-side head movements. The pathophysiology and anatomical basis for this unusual manifestation is still a subject of intense scrutiny.