Long-term results after fractionated radiation therapy for large brain arteriovenous malformations.

Objective: To study the results after fractionated radiotherapy of large arteriovenous malformations (AVMs).

Methods: Twenty-eight patients harboring large AVMs were treated between 1980 and 1985 with fractionated radiotherapy with up to 3.5 Gy per fraction twice a week to a total dose of 41 to 50 Gy. All but 5 patients were examined with an angiogram at least 4 years after the treatment.

Results: Two AVMs (8%) were obliterated after the treatment. Eight patients died: five as a result of hemorrhages, two of unknown causes, and one as a result of lung carcinoma. Five patients deteriorated slightly, three moderately, and four severely after the treatment. The longer the observation time, the higher the incidence of neurological deterioration. The AVMs were significantly larger in the four patients who developed a severe deficit after the treatment. The annual hemorrhage rate was 6% after the treatment, suggesting that radiation did not protect from hemorrhage unless the AVM was occluded. AVMs with a pretreatment rupture had a annual hemorrhage rate of 12%, compared with 1% in the unruptured cases.

Conclusion: The obliteration rate after fractionated radiotherapy with a dose per fraction of 2 to 4 Gy to a total dose of up to 50 Gy was low. The clinical outcome suggests that the radiation treatment may have caused significant side effects. Although the risk for hemorrhage in previously ruptured large AVMs is high, the use of fractionated radiotherapy using low doses per fraction cannot be recommended.