Brain tumors with cysts treated with Gamma Knife radiosurgery: is microsurgery indicated?

Cysts, which are not uncommonly associated with brain tumors, may be responsible for neurological dysfunction. Stereotactic aspiration of such lesions can lead to clinical improvement, but cyst recurrence is common and multiple aspirations may be necessary. Thirteen cases of brain tumors with cystic components were treated by radiosurgery with follow-up of 5-29 months (median 14 months). The tumor diagnoses were three cystic craniopharyngiomas, two brain stem cystic astrocytomas, two cystic cerebellar astrocytomas, one cerebellar hemangioblastoma, one ganglioglioma, one fourth ventricle tumor, one cerebellopontine angle pilocytic astrocytoma, one metastasis from lung cancer and one glioblastoma. The dose at the tumor margin ranged between 10 and 20.5 Gy (mean 15.5 Gy) and the maximum dose ranged between 18 and 45 Gy (mean 32.3 Gy). In 11 of these cases the cystic component recurred in spite of a decrease in the size of the solid tumor component. An Ommaya reservoir was inserted in six cases, stereotactic aspiration was performed in two cases, microsurgery was undertaken in two cases after 2-8 months (mean 4.8 months) and one patient refused further treatment. Multiple aspirations through the Ommaya reservoir were performed in the outpatients on the two patients who required them. It may be appropriate to be cautious in advising radiosurgery for intracranial tumors with a significant cystic component. Microsurgery if possible may be preferable in this situation.