A congenital abnormality of the central nervous system marked by failure of the midline structures of the cerebellum to develop, dilation of the fourth ventricle, and upward displacement of the transverse sinuses, tentorium, and torcula. Clinical features include occipital bossing, progressive head enlargement, bulging of anterior fontanelle, papilledema, ataxia, gait disturbances, nystagmus, and intellectual compromise. (From Menkes, Textbook of Child Neurology, 5th ed, pp294-5)

(dandy-walker malformation) A rare congenital brain malformation disorder characterized by agenesis or hypoplasia of the cerebellar vermis, cystic dilatation of the fourth ventricle, and enlargement of the posterior fossa.

Dandy-Walker complex i s a group of disorders that affect the development of the brain. The changes in brain development are present from birth (congenital). Dandy-Walker complex affects the formation of the area of the brain known as the cerebellum, which is responsible for coordinating movement, and the fluid-filled spaces around it....