gms | German Medical Science

Objective: Arteriovenous malformations are currently classified by their size, location (eloquent/non-eloquent) and depth of venous drainage to estimate the risk of bleeding and treatment choice. We hypothesized that in addition to the so far used classification of Spetzler Martin the number of draining veins implies a significant predicting risk factor, too.

Methods: 238 patients harboring AVMs admitted to our department between 2006 and 2016 were analyzed with regard to the angioarchitecture. Size and quantity of draining veins, hemorrhage status, Spetzler & Martin grade, and supra- and infratentorial location were taken into account.

Results: Hemorrhage was found in 99 patients (41.6%), mostly in AVMs Spetzler-Martin grade 3. At admission, 70 (70.7%) patients of these showed a good state (WFNS I-III) and 30 patients (30.3%) a poor state (WFNS IV-V). AVMs with less than 3 draining veins into the sinus were more frequently associated with hemorrhage (56.4% vs. 22.9%, p < 0.0001, OR 4.36). Bleeding had occurred in 62.8% of patients with an infratentorial AVM whereas this was the case in only 36.9% of patients with a supratentorial AVM (62.8% vs. 36.9%, p=0.003; OR 0.35). Location and associated aneurysms were not significantly (p > 0.05) related to the number of draining veins. Favorable outcome (mRs 0-2) was achieved in 78 (78.8%) of the patients with hemorrhage.

Conclusion: AVMs with less than three draining veins show a hemorrhage significantly more frequently than AVMs with a higher number of draining veins. In addition to the classification criteria used so far, number of draining veins should be included into the AVM grading system to assess the hazardousness and treatment option for preventing bleeding.