Radiosurgery in cerebral tumours and AVM.

In collaboration with the Institute of Neurosurgery, La Sapienza Rome University, we have treated 214 patients with stereotactic irradiation. The series began in March 1984 and includes 198 cerebral tumours of different histology and 16 AVM. 73% of the patients had been operated on before irradiation. From this first experience the following considerations can be drawn: (a) radiosurgery is not an alternative to neurosurgery except for particular cases; neurosurgery is therefore essential because the smaller the target area the higher the efficiency of stereotactic irradiation; (b) compared to conventional radiotherapy, damage to the brain is minimized as shown by NMR. The follow-up time is too short to allow any definite conclusion. However, positive effects have been observed in malignant gliomas and single metastases. In craniopharyngiomas and pituitary adenomas, tumour growth was arrested or decreased with the disappearance of the tumour in 3 adenomas and 1 craniopharyngioma. With regard to the response of meningiomas to irradiation we have shown that radiosurgery is able to cause a decrease in tumour size as well as reduced contrast enhancement, probably due to vascular changes and fibrosis. In AVM the efficiency of radiosurgery has been further confirmed.