Dandy-Walker syndrome (DWS) is a congenital brain malformation involving the cerebellum and fourth ventricle. We report a 6-month-old girl with DWS presenting an initially normal ventricular system and mild
cyst-like lesion over the posterior fossa as assessed by postnatal brain sonography. However, symptoms and signs of increased intracranial cerebral pressure in terms of frequent
vomiting and tense anterior fontanel developed, and these were associated with mild
hypotonia and poor neck support, and upward-gaze
palsy at the age of 6 months. Magnetic resonance imaging revealed a huge cystic lesion of the fourth ventricle, which filled the posterior fossa and ventricular dilatation. The tentorium was progressively displaced upward by the
cyst. A nearly complete agenesis of the cerebellar vermis was also confirmed. After a successful
endoscopic third ventriculostomy, a series of brain magnetic resonance imaging scans, taken during a follow-up survey, showed normal lateral and third ventricles. Consequently, symptoms of intracranial cerebral pressure resolved, and a developmental milestone was achieved. In conclusion, DWS can be confirmed postpartum, and
endoscopic third ventriculostomy was found to be a preferential operative procedure for DWS with
hydrocephalus. It may be effective for patients younger than 1 year.