Gamma unit radiosurgery in cerebral arteriovenous malformations

Among 25 patients with cerebral arteriovenous malformation (AVM), who were followed for more than two years after gamma unit radiotherapy, treatment outcomes were unsatisfactory in 8 patients. The patients consisted of 2 patients whose AVMs were angiographically shown to have not been completely obliterated following the initial treatment and were therefore reirradiated, 3 who refused further angiographic examination, despite only partial obliteration of the nidus having been obtained, and 2 patients with complete nidus obliteration with radiation-related morbidity or with angiography-related mortality. In the remaining one patient, no neurodiagnostic imaging studies have thus far been performed because the patient has refused them. Factors which could have contributed to unsatisfactory treatment outcomes in these 8 patients were as follows (3 patients had multiple factors): 1) inappropriate patient selection criteria for this procedure (3), 2) poor delineation of the AVM on stereotactic angiography (one), 3) imprecise delivery of the radiation dose due to incorrect dose planning (3), and 4) inadequate follow-up after radiosurgery (4). Successful radiosurgical treatment requires appropriate patient selection and precise delivery of the radiation dose to the target, as is well known. Furthermore, we emphasize that meticulous long-term follow-up is essential in successfully managing all radiosurgically-treated AVM patients. (author)