Acute spontaneous hemorrhage after embolization of brain arteriovenous malformation with N-butyl cyanoacrylate

Purpose: To investigate factors predisposing to spontaneous hemorrhage in t he early period after embolization of brain arteriovenous malformations (AV Ms) Methods: The authors report 15 cases of spontaneous hemorrhage in a consecu tive series of 492 brain AVMs totally or partially treated with intranidal injections of a polymerizing mixture, from 1984 to June 1998. Retrospective analysis of the records was performed with special attention to the angio- architectural features before embolization, details of embolization procedu res and induced angiographic modifications. Results: Pre-embolization features of greater incidence were the presence o f steal phenomena (87 %), multiple feeding arteries (100 %), a compact aspe ct of the nidus (93 %), and lobar topography (87 %). In most cases the volu me of injected glue exceeded 1 ml (80 %), venous embolization was significa nt (67 %) and immediate angiographic control showed venous stagnation in an d/or around the nidus (80 %). Four patients were asymptomatic (incidental d iscovery on systematic CT at day 3). Among the remaining 11 symptomatic pat ients, 6 were operated to evacuate an intracerebral hematoma, outcome was g ood for 4, 5 were left with sequelae and 2 died. Conclusion: Spontaneous hemorrhagic complications affected 3.04 % of emboli zed patients. The combination of certain angio-architectural features, sign ificant venous embolization and persistent venous stagnation within the nid us seem to have sonic predictive value of high risk hemorrhage. In light of this, additional preventive measures must be taken and a neurosurgical tea m systematically kept on standby.