The following is quoted directly from Med Scape Reference
.Dandy-Walker malformation is a rare congenital malformation that involves the cerebellum and fourth ventricle. Dandy-Walker malformation is characterized by agenesis or hypoplasia of the cerebellar vermis, cystic dilatation of the fourth ventricle, and enlargement of the posterior fossa. A large number of concomitant problems may be present, but Dandy-Walker malformation is recognized whenever these 3 features are found. Approximately 70-90% of patients have hydrocephalus, which often develops postnatally. Dandy-Walker malformation may be associated with atresia of the foramen of Magendie and, possibly, the foramen of Luschka
Mega cisterna magna consists of an enlarged posterior fossa secondary to an enlarged cisterna magna, with a normal cerebellar vermis and fourth ventricle.
The only reason I am quoting this is because I am not a doctor, and I want to have this information available for myself and others.
