Postembolization neurological deficits in cerebral arteriovenous malformations: stratification by arteriovenous malformation grade.

OBJECTIVE: To stratify the risk of embolization during the treatment of cerebral arteriovenous malformations (AVMs) by grade and to assess its impact on the overall treatment risk.
METHODS: Patients with cerebral AVMs treated with embolization between 1995 and 2004 were retrospectively reviewed. Age, sex, AVM grade, location of lesion, number and location of embolized arteries, and number of embolization sessions were analyzed with respect to neurological or vascular complications after embolization.
RESULTS: Embolization was performed in 153 patients: 508 vessels were embolized during 203 sessions (mean, 3.3 vessels per patient). The mean angiographic and clinical follow-up periods were 1.7 and 2.1 years, respectively (range, 3-60 mo). The periprocedural morbidity and mortality rate was 11.8%, but at the last follow-up examination, only 2% of survivors were significantly disabled (modified Rankin score > 2). One (0.7%) patient died, and 17 patients experienced unexpected neurological deficits immediately after embolization. Five of these patients demonstrated near or total recovery during follow-up. The number of branches embolized was the only variable significantly related to neurological deficit (P < 0.017). The long-term rates of neurological deficits after embolization were 0, 5, 7, 10, and 18%, respectively, for AVM Grades I through V. Among 114 patients who underwent preoperative embolization, follow-up deficit rates of Grades I through V were 0, 5, 6, 6, and 25%, respectively. Long-term permanent deficits from embolization occurred in 8.6% of patients.
CONCLUSION: Endovascular treatment carries a procedural risk related to AVM grade and number of branches treated. This risk should be weighed carefully in the context of overall treatment morbidity and mortality.