Inspection of the posterior fossa is a common feature of prenatal ultrasound and is used primarily to determine whether excess fluid or malformations of the cerebellum exist.[6] Anomalies of the cerebellar vermis are diagnosed in this manner and include phenotypes consistent with Dandy-Walker malformation, rhombencephalosynapsis, displaying no vermis with fusion of the cerebellar hemispheres, pontocerebellar hypoplasia, or stunted growth of the cerebellum, and neoplasms. In neonates, hypoxic injury to the cerebellum is fairly common, resulting in neuronal loss and gliosis. Symptoms of these disorders range from mild loss of fine motor control to severe mental retardation and death.