A structuraldevelopmental abnormality occurring during embryonic development in which the cerebellar vermis has not developedappropriately (partially or completely absent) and there is dilatation of the fourth ventricle. As with Chiari II malformation, it is frequently associated with agenesis of the corpus callosum, and also hydrocephalus (20-80% of cases). Infants with the malformation can manifest delayed motor development, with progressive enlargement of the skull. Other signs include breathing and collimator problems, as well as malformations of the face, fingers, heart and toes. However, its relationship with mental development is variable: some children display typical cognitive development, with others being quite severely affected. It is named after two neurosurgeons: Walter Dandy (1886-1946) and Arthur Earl Walker (1907-1995).
See Cerebellum (anatomy), Cerebellum (development), Cerebellum disorders, Chiari II malformation, Corpus callosum, Hydrocephalus (or hydrocephaly), Ventricle