Simple cysts of the cerebellum.

Four cases of simple cyst of the cerebellum treated at Stanford University Medical Center are presented. Review of the literature and past experience at Stanford suggest that they are uncommon. They seem to occur most often in middle age, presenting the signs and symptoms of an expanding cerebellar mass, and appear to be adequately treated by unroofing and draining the cyst cavity. It is suggested that these cysts do not have a congenital origin but rather represent a degenerated form of cerebellar astrocytoma.