The most common malignant brain tumor in children, occurring most often in the cerebellum or posterior fossa in the vicinity of the fourth ventricle. It is ten times more likely to occur in children than adults, with the incidence being higher in boys (62%) than in girls (38%). The cells of origin of these tumors is unknown, but have been hypothesized to arise from cerebellar stem cells. The functional effects of this tumor are mainly due to a blockage of the fourth ventricle that gives rise to secondary increased intracranial pressure. The effects initially include debilitating headaches, followed by listlessness, and frequent bouts of vomiting and dizziness. Subsequently, there are problems with movement coordination that manifest themselves as ataxia, falls, nystagmus and difficulties with swallowing.
See Ataxia, Cerebellum (development), Incidence, Nystagmus, Ventricle