"No-no" type bobble-head doll syndrome in an infant with an arachnoid cyst of the posterior fossa: a case report.

BACKGROUND

Bobble-head doll syndrome is a rare and surgically treatable movement disorder characterized by up-and-down (yes-yes) head bobbing occurring at a rate of 2-3 Hz. Side-to-side (no-no) head bobbing is less frequently described. Bobble-head doll syndrome is usually associated with dilation of the third ventricle, but is rarely associated with posterior fossa disease.

PATIENT

We describe an infant with fetal hydrocephalus and an arachnoid cyst of the posterior fossa. Endoscopic fenestration of the arachnoid cyst was performed on postnatal day 12. A routine examination at 4 months indicated the infant showed "no-no" type head bobbing, but no other neurological disorder was observed. The third ventricle was dilated during the perioperative period, but not at 2-4 months. In contrast, cerebellar compression decreased gradually and persisted at 4 months.

CONCLUSION

Although few patients with bobble-head doll syndrome do not have third ventricle dilation, these patients typically show cerebellar dysfunction. Our findings support the hypothesis that cerebellar dysfunction is present in bobble-head doll syndrome when third ventricle dilation is absent.