Head bobbing in a patient with a cyst of the third ventricle.

The case of a 7 year-old boy with 'bobble head doll syndrome' associated with a cyst in the third ventricle is reported. This movement disorder appears in early childhood and consists mostly in a rhythmic to-and-fro bobbing of the head and eventually of the trunk. As in three previously described cases, this case showed only slight decrease of the 'tic' after partial removal of the cyst by transcortical exploration of the third ventricle.