Adjuvant embolization with N-butyl cyanoacrylate in the treatment of cerebral arteriovenous malformations: outcomes, complications, and predictors of neurologic deficits.

BACKGROUND AND PURPOSE The purpose of this study was to assess the frequency, severity, and predictors of neurological deficits after adjuvant embolization for cerebral arteriovenous malformations. METHODS From 1997 to 2006, 202 of 275 patients with arteriovenous malformation received embolization before microsurgery (n=176) or radiosurgery (n=26). Patients were examined before and after endovascular embolization and at clinical follow-up (mean, 43.4+/-34.6 months). Outcome was classified according to the modified Rankin Scale. New neurological deficits after embolization were defined as minimal (no change in overall modified Rankin Scale), moderate (modified Rankin Scale < or =2), or significant (modified Rankin Scale >2). RESULTS Two hundred two patients were treated in 377 embolization procedures. There were a total of 29 new clinical deficits after embolization (8% of procedures; 14% of patients), of which 19 were moderate or significant. Postembolization deficits resolved in a significant number of patients over time (P<0.0001). Five patients had persistent neurological deficits due to embolization (1.3% of procedures; 2.5% of patients). In multivariate analysis, the following variables significantly predicted new neurological deficit after embolization: complex arteriovenous malformation with treatment plan specifying more than one embolization procedure (OR, 2.7; 95% CI, 1.4 to 8.6), diameter <3 cm (OR, 3.2; 95% CI, 1.2 to 9.1), diameter >6 cm (OR, 6.2; 95% CI, 1.0 to 57.0), deep venous drainage (OR, 2.7; 95% CI, 1.1 to 6.9), or eloquent location (OR, 2.4; 95% CI, 1.0 to 5.7). These variables were weighted and used to compute an arteriovenous malformation Embolization Prognostic Risk Score for each patient. A score of 0 predicted no new deficits, a score of 1 predicted a new deficit rate of 6%, a score of 2 predicted a new deficit rate of 15%, a score of 3 predicted a new deficit rate of 21%, and a score of 4 predicted a new deficit rate of 50% (P<0.0001). CONCLUSIONS Small and large size, eloquent location, deep venous drainage, and complex vascular anatomy requiring multiple embolization procedures are risk factors for the development of immediate postembolization neurological deficits. Nevertheless, a significant number of patients with treatment-related neurological deficits improve over time. The low incidence of permanent neurological deficits underscores the usefulness of this technique in carefully selected patients.