Dandy-Walker Malformation

Dandy-Walker malformation is a rare congenital malformation and involves the cerebellum and fourth ventricle. The condition 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 the syndrome exists whenever these three 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. Dandy-Walker malformation first was described by Dandy and Blackfan.1 Since the original description, additional studies have reported on the various morphologic features of the syndrome. Not until 1954 did Benda first emphasized that atresia of the cerebellar outlet foramina is not an essential feature of the condition and suggested the now widely accepted term DandyWalker malformation.2 Studies by Hart et al.3 further defined the characteristic triad of Dandy-Walker malformation as consisting of: Complete or partial agenesis of the vermis. 1. Cystic dilatation of the fourth ventricle. 2. An enlarged posterior fossa with upward displacement of lateral sinuses, 3. tentorium, and torcular herophili. The triad typically is found in association with supratentorial hydrocephalus, which should be considered a complication rather than part of the malformation complex .