Background Stereotactic radiosurgery is an alternative to resection of intracraniaI cerebral arteriovenous malformations (AVMs),while it will failin some cases.This study aimed to evaluate the changes after stereotactic radiosurgery for AVMs.Methods Nineteen cases with cerebral AVMs had failure after stereotactic radiosurgery therapy.The symptoms and angiography were assessed.All patients underwent microsurgery.Pathologic examination was performed for all cases and electron microscopic examination was carried out in 6 patients.Reaults Seven cases had hemorrhage from 12 to 98 months after stereotactic radiosurgery,5 had headache.4 had refractory encephalon edema,2 had epilepsy as a new symptom and 1 had a pressure cyst 5 years after radiosurgery.Angiography in 18 cases,8-98 months after radiation therapy,demonstrated no significant changes in 5 cases.slight reduction in 9,near complete obliteration in 1 and complete obliteration in 3.An abnormal vessel was found on pathologic examination in 17 cases,even one case had obliterated in angiography.Electron microscopy examination showed vessel wall weakness,but the vessels remained open and blood circulated.One case died because of a moribund state before surgery.The other 18 cases had no new neurological deficiencies,seizure control and no hemorrhage occurred after microsurgery at an average follow-up of 3 years.Conclusion Stereotactic radiotherapy for AVMs should have a long period follow-up.If serious complications occur,microsurgery can be performed as salvage treatment.