Changing role for preoperative embolisation in the management of arteriovenous malformations of the brain

Background: The aim of this study was to analyse the results of the use of preoperative embolisation in the management of arteriovenous malformations of the brain at one institution between 1989 and 1999. Methods: Two hundred and fifty consecutive cases of angiographically confirmed arteriovenous ma lformations underwent surgery by one surgeon. Cases of dural or spinal arte riovenous malformations have been excluded. Forty-five cases underwent preo perative embolisation. Embolisation was mostly by particulate embo[ic mater ial delivered 4 to 6 days before the intended surgery. The incidence of emb olisation declined from 21 cases of the first 50 arteriovenous malformation cases surgically treated to five in the last 50 cases. For arteriovenous m alformations of less than 3 cm, only the first two temporal quintiles had e mbolised cases; six in the first and three in the second. Outcome was measu red by the Modified Rankin Scale. Results: By 12 months (or last follow up, if less than this time has elapsed) following surgery, 1.6% of patients ha d died, 2.4% had a Modified Rankin scale score of 4 or 5, 6.4% had a Modifi ed Rankin scale score of 3, 8.4% had a Modified Rankin scale score of 2, 14 .4% had a Modified Rankin scale score of 1, and 66.8% were without neurolog ical deficit. There was no difference in outcomes in each of the temporal q uintiles. The four deaths were related to intraoperative haemorrhage, ruptu red aneurysm, acute myocardia[ infarction or unrelated infection. Angiograp hic cure was achieved in 244 of 246 surviving cases. The two cases with res idual arteriovenous malformations underwent focussed irradiation. Permanent morbidity could be attributable to embolisation, intraoperative events (re section functional brain, arteriovenous malformation rupture, aneurysm rupt ure or myocardial infarction) or postoperative events (arterio-capillary-ve nous hypertensive syndrome or infection). Of these 29 patients 14 had under gone embolisation. Mortality and major morbidity (Modified Rankin scale sco re greater than 2 due to treatment) occurred in 8.8% undergoing embolisatio n compared with 1.9% not embolised. The cause for major morbidity in these four embolised cases was intraoperative or postoperative haemorrhage. Concl usions: These results reflect that cases selected for embolisation were tho se at most risk from intraoperative haemorrhage. Arteriovenous malformation s that are less than 3 cm in maximal diameter should only rarely be conside red for preoperative embolisation because of their low surgical morbidity. in the presence of a significant deep perforating artery contribution that cannot be effectively embolised the risks of operative haemorrhage is high irrespective of the effectiveness of embolising ancillary non-perforating a rteries. (C) 2000 Harcourt Publishers Ltd.