Cerebellar infarction and internal hydrocephalus.

Four cases of acute cerebellar infarction producing hydrocephalus are presented. Only the patient, who is submitted to surgical decompression of the posterior fossa, survives, while the other three die. In the latter the necropsy shows a hemorrhagic cerebellar softening in the territory of the inferior posterior cerebellar artery, causing tonsillar herniation and impairment of the liquor drainage at the level of the inferior part of the 4th ventricle. It is suggested that the infarction and the hydrocephalus further progress in "avalanche effect", which is fatal unless prompt surgical decompression can be carried out.