Schwannoma of the fourth ventricle presenting with hemifacial spasm. A report of two cases.

Two cases of cystic brainstem schwannomas protruding into the fourth ventricle are described. Both patients presented with hemifacial spasm. While there is only one previous case report of an intraventricular brainstem schwannoma, there has been no prior description in the literature of hemifacial spasm associated with such a tumor. The clinical, radiographic, surgical, and histopathological features of these tumors are elaborated. The relationship of hemifacial spasm to the various putative theories of origin proposed for intraparenchymal schwannomas is discussed.