CELL RESTS IN THE REGION OF THE FOURTH VENTRICLE: III. Their Relationship to the Development of Gliomas

TUMORS involving the fourth ventricle have been studied intensively by various investigators¹ since Balme-Degarray first reported such a case in 1836.² With the impetus provided by the development of neurosurgery after the turn of the century, reports of a large number of cases were accumulated, permitting certain generalizations to be made regarding tumors involving the fourth ventricle. These may be briefly summarized as follows: Tumors in this region occur most commonly in children and young adults. The commonest tumors involving this region are astrocytomas, medulloblastomas, and ependymomas. The medulloblastomas occur in the midline in the posterior part of the roof of the fourth ventricle³; the astrocytomas usually occur in the midline,⁴ but may also lie laterally and extend into the cerebellar hemisphere.⁵ The ependymomas, too, usually occur in the midline of the roof, but may occur laterally or arise from the floor of the fourth