D

Abstract

The Dandy–Walker syndrome is a developmental abnormality characterized by a failure of development of the midline portion of the cerebellum, which results in a cyst-like enlargement of the fourth ventricle, with bulging of the occipital bone posteriorly and upward displacement of the tentorium and torcula. There may be associated agenesis of the corpus callosum, dilatation of the central aqueduct and third and lateral ventricles, and aplasia of the cerebellar vermis. There is sometimes a tendency for radiologists to overdiagnose a large cisterna magna in adult patients as “Dandy–Walker syndrome.”