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. The syndrome has never been described in a patient with both hydranencephaly and Chiari type 3 malformation. We describe a 2-year-old female patient who presented with congenital hydrocephalus, an occipital encephalocele and rhythmic bobbling of the head. Imaging investigation revealed a Chiari type 3 malformation and hydranencephaly. The patient was taken to theatre for a ventriculoperitoneal shunt insertion, and at day 3 post operatively, the patient had a markedly decreased head circumference and a decrease in the frequency of the bobbling of the head. A further review at 2 weeks showed that the bobbling of the head had ceased. Although the pathophysiology of bobble-head doll syndrome is yet to be fully understood, there has been postulation of either a third ventricular enlargement or a cerebellar dysfunction to explain bobble-head doll syndrome. Our case illustrates that the pathophysiology is most likely multifactorial as illustrated by the fact that by just addressing the high intracranial pressure with a shunt was sufficient to treat the condition.