<prompt> Regarding Dandy-Walker syndrome, all are seen except-HydrocephalusArachnoid cystPosterior fossa cystCerebellar vermis deficiency  <response>: Dandy-walker malformationThe Dandy-Walker malformation consists of a cystic expansion of the 4th ventricle in the posterior fossa and midline cerebellar hypoplasia.There is : -Hydrocephalus 90 of casesAgenesis of the cerebellar vermis and corpus callosum.The rapid increase in head size with prominent occiput. 