Objective: The aim of this two-part study is to give a full account of all patients referred for embolization of arteriovenous malformations (AVMs) from 1987 to 1993. This article (Part I of II) presents the patient study, including angiographic features and their relation to the immediate outcome of embolization.
Methods: Of the 192 patients referred, 150 were subsequently treated. Most patients were referred by neurosurgeons, and 85% of the AVMs were Spetzler-Martin Grade > or = 3. We have accounted for the 42 patients who did not undergo embolization.
Results: Occlusion from embolization alone (total embolization) was obtained in 13% of patients. Full treatment (total embolization or embolization and then stereotactic radiation or surgery) was achieved in two-thirds of all patients (n = 100, 66%), and combined treatment with stereotactic gamma radiation was the most important part of the treatment strategy. The procedural mortality was 1.3%. The total incidence of complications after embolization was high (40%), but only 6.7% of cases were labeled severe. Of all angiographic features that were considered, large size and the presence of deep feeders were predictors of failure to achieve full treatment. Thirty-four patients with AVMs < 8 cc were included in the study. These could have been irradiated as the sole treatment. In this group of small AVMs, the results of embolization were far better than in the whole group. Fourteen of the AVMs had volumes of < 4 cc, and 10 of these (71%) were totally embolized. One patient had a hemianopsia. Among AVMs 4 to 8 cc in volume (n = 20), the total embolization rate was 15%, the full treatment rate in combination with gamma treatment was 75%, and 10% of the patients were operated on after embolization. Severe complications occurred in 15% of patients, but no complications occurred after November 1990.
Conclusion: In a series of AVMs, most of which were regarded as unsuitable for surgical excision, two-thirds were reduced to a size suitable for gamma knife treatment or totally occluded by embolization alone. The total complication rate was high, but the combined rate of death and complications affecting lifestyle was 8.0%, equal to approximately 3.2 years of natural history.