Quantitative ventricular volume changes after endoscopic third ventriculostomy in children with Dandy-Walker malformation.

PURPOSE: Hydrocephalus occurs in up to 80% of children with Dandy-Walker malformation (DWM). Although endoscopic third ventriculostomy (ETV) is increasingly used as a primary treatment, quantitative data regarding changes in ventricular and posterior fossa cyst volumes remain limited. We evaluated volumetric changes following ETV and correlated them with clinical outcomes.

METHODS

This retrospective study included children with DWM who underwent primary ETV for hydrocephalus between 2015 and 2024. Patients with a history of shunting or secondary fourth ventricular outlet obstruction were excluded. Preoperative and 3-month postoperative MRI scans were analyzed using semiautomated volumetry. Total supratentorial ventricular volume (V1) and posterior fossa cyst volume (V2) were calculated. Clinical improvement, stoma patency, and need for re-intervention were assessed.

RESULTS

Thirty children (23 boys; 40% < 1 year) underwent ETV with a mean follow-up of 30.6 months. The overall success rate was 66.7%, with most failures occurring within four months. Paired volumetric analysis was available in 10 patients. Mean supratentorial ventricular volume decreased significantly from 708.7 ± 411.2 cc preoperatively to 550.4 ± 361.3 cc postoperatively (mean reduction 25.2%; p = 0.004). Posterior fossa cyst volume decreased from 173.0 ± 164.7 cc to 153.0 ± 168.1 cc (mean reduction 19.2%; p = 0.016), though reduction was inconsistent. Ventricular volume reduction correlated and CSF flow across the stoma with good clinical outcomes, whereas cyst volume reduction did not consistently predict clinical improvement.

CONCLUSION

ETV provides effective shunt-free treatment for hydrocephalus in majority DWM patients. Reduction in supratentorial ventricular volume correlates with clinical success, while posterior fossa cyst regression appears variable and not essential for a favorable outcome.