Gamma Knife Radisurgery of Lateral Ventricular Neoplasm

ABSTRACT

Surgical access to the lateral ventricle is always gained through sectioning the corpus callosum or cerebral cortex. Besides the destruction of normal tissue, total removal of a tumor is often difficult and potential complications may occur due to a narrow and deep surgical field. However, stereotactic radiosurgery has a number of advantages in treating lateral ventricular tumors. Thre are less critical structures around the lateral ventricle. The large proportion of the tumors is surrounded by CSF instead of normal brain tissue. Tumors in this location often are benign and well demarcated on MRI. Among 382 intracranial tumors which have undergone Gamma Knife radiosurgery between May 192 and April 1996, 13 tumors were in the lateral ventricle(neurocytoma 2, oligodendroglioma 1, giant cell astrocytoma 2, pilocytic astrocytoma 1, glioblastoma multiforme 1, meningioma 3, ependymoma 1, immature teratoma 1, undetermined 1). The marginal dose to the tumor ranged from 6.5 to 18 Gy, most often to the 50% isodose line . Eleven cases were followed-up for 3-42 months with imaging studies. Six tumors almost disappeared with remaining small vestiges 4.3-42 months after radiosurgery. Two had markedly shrunk. Three tumors including 2 meningiomas with short follow-up period(5.8, 5.9 months) had no changes in size. These results suggest that lateral ventricular tumors respond very well to radiosurgery while risky surgical procedures can be avoided.