Angiographic long-term follow-up data for arteriovenous malformations previously proven to be obliterated after gamma knife radiosurgery.

Objective: To investigate whether angiograms obtained 2 years after radiosurgery, proving total arteriovenous malformation (AVM) occlusion, represent the final state of treated AVMs and adjacent normal vessels.
Methods: Angiograms were obtained for 48 patients 5 to 24 years after gamma knife radiosurgery and 4 to 17 years after the AVMs had been proven to be totally occluded after the treatment; changes in normal vessels and signs of recanalization were recorded. Ten of the patients developed clinical symptoms attributable to the AVMs or the treatment after having been declared cured, whereas the other patients did not exhibit symptoms.
Results: There was evidence of AVM nidi at the sites of previously occluded AVMs for two patients and of nidi adjacent to those sites for another two patients. Three of the four recurrent AVMs were associated with hemorrhaging. All patients who experienced hemorrhaging from previously occluded AVMs were < or = 14 years of age at the time of gamma knife radiosurgery. There were signs of segmental narrowing in normal vessels that had been irradiated with high doses (nine patients) or a low dose (one patient). The segmental narrowing decreased with time for four of these patients, was unchanged for four, and increased for two. These vascular changes did not produce clinical symptoms in any of the patients.
Conclusion: There is a small possibility that AVMs may reappear after having been totally occluded after radiosurgery, especially in pediatric patients. Segmental narrowing in normal arteries after radiosurgery is a benign condition that rarely progresses and does not produce clinical symptoms.