Radiosurgery of cerebral arteriovenous malformations: Is an early angiogram needed?

BACKGROUND AND PURPOSE: Radiosurgical treatment of arteriovenous malformati ons (AVMs) has slow and progressive vasoocclusive effects. We sought to det ermine if early posttherapeutic angiography provides relevant information f or the management of radiosurgically treated AVMs. METHODS: Between 1990 and 1993, the progress of 138 of 197 cerebral AVMs tr eated by linear accelerator (Linac) was regularly followed by angiographic study. On each posttherapeutic angiogram ("early," 6-18-month follow-up; "i ntermediate," 19-29-month-follow-up; and "late," > 30-month follow-up), the degree of reduction across the greatest diameter of the nidus and hemodyna mic modifications were analyzed. Each cerebral AVM was qualitatively classi fied into one of the following categories after early angiographic study: 0 %-reduced, 25%-reduced, 50%-reduced, 75%-reduced, and 100%-reduced or ''com plete obliteration." Vasooclusive progress for each category was then studi ed over time. RESULTS: Three (10%) of the 30 0-25%-reduced, eight (38%) of 21 50%-reduced , and 27 (84%) of 32 75%-reduced cerebral AVMs showed complete obliteration after further followup, The three 0-25%-reduced AVMS that went on to compl ete obliteration underwent very early angiography (6-7 months). Fifty-five cerebral AVMs showed complete obliteration on early angiograms (40%), In th is group, more follow-up, when performed, confirmed complete obliteration i n all cases (n = 17). CONCLUSION: An early angiogram is needed to predict the effectiveness of ra diosurgery. Important AVM changes seen on early angiograms are highly corre lated with treatment success. Moreover, no or minor changes seen on early a ngiograms are highly predictive of radiosurgical failure. For these patient s, further treatment should be discussed promptly.