Bobble-head doll syndrome due to trapped fourth ventricle and aqueduct

The bobble-head doll syndrome has been associated with third ventriculomegaly due to cysts or aqueductal stenosis. A case is described in which the aqueduct and fourth ventricle are enlarged, but the third ventricle is not. The unifying pathogenesis for this and previous cases is pressure on the dorsomedial red nucleus.