Bobble-head doll syndrome secondary to a giant posterior fossa arachnoid cyst: A rare case report.

BACKGROUND

Bobble-head doll syndrome (BHDS) is a rare movement disorder characterized by rhythmic head oscillations at a frequency of 2-3 Hz, typically in a yes-yes or no-no pattern. It is most commonly associated with suprasellar arachnoid cysts, causing pressure on midbrain structures, thalamus, and cerebrospinal fluid (CSF) pathways, resulting in movement abnormalities and hydrocephalus. While it usually presents in children aged 3-5 years, late adolescent or adult presentations are exceedingly uncommon.

CASE DESCRIPTION: We report a 23-year-old male with progressive involuntary side-to-side head movements since childhood, which had worsened over the preceding year and led to gait instability requiring support. He had a history of ventriculoperitoneal shunt placement in infancy for hydrocephalus, later removed due to infection. Magnetic resonance imaging revealed a large posterior fossa arachnoid cyst compressing the third ventricle, with intermittent CSF obstruction contributing to progressive neurological decline. The patient underwent endoscopic cyst fenestration, which restored CSF circulation and relieved mass effect. Head movements subsided almost completely within 48 h postoperatively, and gait improved significantly over 2 weeks. Six-month follow-up imaging confirmed resolution of ventricular compression and restoration of aqueductal flow.

CONCLUSION

This case highlights a rare delayed presentation of BHDS in adulthood, underscoring the importance of timely surgical intervention. Endoscopic fenestration proved highly effective in restoring CSF dynamics, resolving abnormal movements, and improving functional outcomes, and may offer advantages over CSF diversion alone.