What is Bobble-head doll syndrome?

Bobble-head doll syndrome is a rare neurological movement disorder in which patients, usually children around age 3, begin to bob their head and shoulders forward and back, or sometimes side-to-side, involuntarily, in a manner reminiscent of a bobblehead doll. The syndrome is related to cystic lesions and swelling of the third ventricle in the brain. Symptoms of bobble-head doll syndrome are diverse but can be grouped into two categories: physical and neurological. The most common form of treatment is surgical implanting of a shunt to relieve the swelling of the brain.