1:30,000 births: Dandy-Walker syndrome occurs in approximately 1 in every 30,000 births.
Perinatal as opposed to trapped fourth ventricle that occurs later: As a congenital abnormality, Dandy-Walker syndrome presents at birth. The ability to have a fetal diagnosis is one determinant of whether the condition is Dandy-Walker syndrome or is simply hydrocephalus due to a trapped fourth ventricle.
Female preponderance: The condition is up to three times more common in females.
Maternal use of warfarin: Some studies have suggested a link between maternal use of warfarin during pregnancy and Dandy-Walker malformations (7).
Relationships to Other Disease States and Syndromes
Present in nearly all: 80–90% of patients with a Dandy-Walker malformation have hydrocephalus. Up to 4% of cases of congenital hydrocephalus are Dandy-Walker syndrome associated.
Other CNS anomalies
Posterior fossa anomalies: Other developmental abnormalities of the posterior fossa besides those seen in the cerebellum’s vermis are caused by the enlarged fourth ventricle.
Cephaloceles and agenesis of corpus callosum: Dandy-Walker syndrome is associated with other CNS abnormalities, such as agenesis of corpus callosum and cephaloceles, 20–70% of the time.
Dandy-Walker variant: The Dandy-Walker variant connotes a version of Dandy-Walker syndrome with a lesser degree of vermian abnormalities and less fourth ventricular enlargement.
PHACES syndrome: Dandy-Walker syndrome often occurs in patients with PHACES syndrome.