Symptomatic Radionecrosis after AVM Stereotactic Radiosurgery. Study of 16 Consecutive Patients

The purpose of our study was to analyze the outcome of symptomatic radionecrosis following stereotactic radiosurgery for brain arteriovenous malformations. Of 225 patients treated by linear accelerator radiosurgery for brain AVM, 16 (7,1%) presented post-radiosurgery symptomatic radionecrosis on a mean follow-up period of 50 months (range 1-123 months). Once diagnosed with radionecrosis, 14 of 16 patients were subjected to high dose corticotherapy consisting of escalating doses of dexamethasone for several weeks. The mean interval of occurrence of new symptoms was 11.6 months post-radiosurgery (range 6-20 months). The mean time of follow-up was 2.9 years post radiotherapy ranging from seven months to eight years. Of the 16 patients with symptomatic radionecrosis, 11 (68,75%) showed complete resolution of symptoms while five (31,25%) showed improvement but still presented a neurological deficit at the closing date of the study. At the closing date, 11 patients (68.75%) had angiographically completely obliterated arteriovenous malformations while another two patients had an obliteration of 95% to 98% and one patient had a 98% obliteration with development of a new contralateral AVM. In our series, symptomatic radionecrosis occurred in 7.1% of patients treated with stereotactic radiosurgery for brain AVM. These patients where subjected to a prompt, high dose corticosteroid treatment and most presented symptom resolution or improvement with a fair obliteration rate, offering protection from bleeding. Permanent neurologic deficits attributable to radionecrosis occurred in 2.2% of our patient population treated with stereotactic radiosurgery for brain AVM.