Demographic, morphological, and clinical characteristics of 1289 patients with brain arteriovenous malformation

Background and Purpose-The purpose of this study was to assess demographic, clinical, and morphological characteristics of patients with brain arterio venous malformations (AVMs). Methods-Prospectively collected data of 1289 consecutive AVM patients from 3 independent databases (1 multicenter [Berlin/Paris/Middle and Far East, n =662] and 2 single centers [New York, n=337, and Toronto, n=290]) were anal yzed. The variables assessed were age at diagnosis, sex, AVM size, AVM drai nage pattern, AVM location in functionally important brain areas ("eloquenc e"), and type of presentation (hemorrhage, seizure, chronic headache, or fo cal neurologic deficit). Comparisons were made by ANOVA, contingency tables , and log-linear models. Results-Overall, mean age at diagnosis was 31.2 years (95% CI 30.2 to 32.2 years), and 45% of the patients were female (95% CT 42% to 47%). AVM maximu m diameter was <3 cm in 38% (95% CI 35% to 41%). Deep venous drainage was p resent in 55% (95% CI 52% to 59%). An eloquent AVM location was described i n 71% (95% CI 69% to 74%). AVM hemorrhage occurred in 53% (95% CI 51% to 56 %). Generalized or focal seizures were described in 30% (95% CI 27% to 33%) and 10% (95% CI 8% to 12%), respectively. Chronic headache was recorded in 14% (95% CI 12% to 16%). Persistent neurological deficits were found in 7% (95% CI 6% to 9%), and progressive neurological deficits in 5% (95% CI 4% to 6%). Significant differences between centers were found for age (P<0.001 ), sex (P=0.04), eloquence (P=0.04), size (P<0.001), hemorrhage (P=0.006), persistent neurological deficit (P<0.001), and reversible neurological defi cit (P=0.013). The intercenter difference found for hemorrhage frequency di d not remain after adjustment for AVM size. Conclusions-Baseline characteristics differed considerably between centers. The differences found in patient age and AVM size may be explained by cent er-specific referral patterns and the influence of access to treatment reso urces, whereas those found for other characteristics may be attributable to center-specific definitions. Analysis of natural history data from tertiar y referral center databases may be improved by consistent definitions appli cable to the entire population of AVM patients.