Objective: Previous reports of seizure outcomes after arteriovenous malformation (AVM) treatment have involved single-treatment modality (surgery, radiosurgery, or embolization) series. Such series reflect only selected lesions, of certain sizes, locations, and other clinical and anatomic characteristics, that are amenable to the single therapy, limiting the analysis of those factors. We report the results of AVM treatment using a multimodality approach that we think encompasses a broader spectrum of treatable brain AVMs. We tested for factors associated with seizure presentation and seizure outcomes.
Methods: Between 1991 and 1999, the multidisciplinary neurovascular unit at Massachusetts General Hospital treated 424 patients with brain AVMs. Treatment consisted of surgical resection, radiosurgery, or embolization, either alone or in combination. One hundred forty-one patients (33%) experienced seizures before treatment. We studied the following factors: sex, age, AVM size, AVM location, occurrence of intracranial hemorrhage, seizure type, duration of seizure history, treatment modality, and AVM obliteration. We tested for statistical associations between these factors and seizure presentation and outcomes. Clinical follow-up monitoring was via mailed questionnaires.
Results: When we compared the 141 patients with seizures with the 283 patients who did not experience seizures (total of 424 patients), male sex, age of less than 65 years, AVM size of more than 3 cm, and temporal lobe AVM location were statistically associated with seizures (P < 0.01, P < 0.05, P < 0.0001, and P < 0.01, respectively). Posterior fossa and deep locations were statistically associated with no seizures (P < 0.0001). One hundred ten (78%) of the 141 patients who experienced seizures before treatment responded to the mailed questionnaires, with a mean follow-up period of 2.9 years. A detailed comparison of responders and nonresponders demonstrated no statistically significant differences in pertinent characteristics. As determined with the Engel Seizure Outcome Scale, there were 73 (66%) Class I (free of disabling seizures), 11 (10%) Class II (rare disabling seizures), 1 (0.9%) Class III (worthwhile improvement), and 22 (20%) Class IV (no worthwhile improvement) outcomes. Three patients died during the follow-up period. We tested for factors associated with Engel Class I outcomes. Sex, age, and AVM size were not associated with Class I outcomes. Short seizure history, association of seizures with intracranial hemorrhage, generalized tonicoclonic seizure type, deep and posterior fossa AVM locations, surgical resection, and complete AVM obliteration were statistically associated with Class I outcomes (P < 0.0001, P < 0.05, P < 0.05, P < 0.05, P < 0.001, and P < 0.001, respectively). When only completely obliterated AVMs were considered, there were no statistically significant differences between surgery, radiosurgery, and embolization.
Conclusion: Certain factors, as identified in an analysis of a wide spectrum of treatable brain AVMs, can facilitate predictions of the incidence of seizure presentation with AVMs, as well as seizure outcomes after multimodality treatment.