Tumors primarily located in the third ventricle are rather rarely encountered when one considers the relative frequency with which other portions of the brain are involved by neoplastic diseases. Weisenburg,1 in 1910, found twenty-seven such cases in the literature, reporting at the same time three of his own. Since then many more cases of tumor of the third ventricle have been reported. Weisenburg grouped these tumors into three definite classes: those arising from the floor of the ventricle and producing no obstruction to the flow of cerebrospinal fluid; those obstructing the foramina of Monro, and capable of changing position by deviation of the head, and those extending into the aqueduct, affecting the surrounding structures by direct extension or by pressure alone.
It is the last type of tumor in which we are especially interested. That the diagnosis of a neoplasm in this region can be made if there is
ALLEN SS, LOVELL HW. TUMORS OF THE THIRD VENTRICLE. Arch NeurPsych. 1932;28(5):990-1006. doi:10.1001/archneurpsyc.1932.02240050024002