The Dandy-Walker Malformation is a term which represents not just a single entity, but rather several abnormalities of brain development which exist simultaneously. It was first described by Dandy and Blackfan in 1914.
This malformation is typically characterized by incomplete formation of the cerebellar vermis, dilation of the fourth ventricle, and enlargement of the posterior fossa. Although earlier, traditional descriptions of this complex include the incomplete formation of several fourth ventricular outlet pathways for the cerebrospinal fluid (CSF), it is now known that this occurs in only a minority of affected individuals.
The above noted developmental abnormalities generally result in the formation of posterior fossa cyst(s) which communicate(s) with an enlarged fourth ventricle. The mean incidence of this complex in individuals with hydrocephalus is estimated to be 3%. There is no statistically significant sex prevalence.
Eigthy percent of cases are diagnosed before the age of one year, typically as a result of the associated hydrocephalus. The malformation may have a number of other, associated anomalies in the brain's development including agenesis of the corpus callosum, occipital encephalocele, occular abnormalities and cleft palate. | |
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