BackgroundThe treatment of low grade Spetzler-Martin (SM) brain arteriovenous malformations (AVMs) has been debated in unruptured cases. Nevertheless, in clinical practice there are cases where treatment is preferred; in these cases a very low complication rate is mandatory. In ruptured cases, early and complete obliteration of the nidus is the preferred strategy.ObjectiveTo achieve curative embolization, ideally in a single session, by dual microcatheterization techniques with arterial and/or venous access, according to the angioarchitecture.Materials and methodsThis is a prospective, single-center study carried out between January 2008 and January 2016. Patients with ruptured and unruptured brain AVMs, with SM grades I and II, treated by endovascular means, were included. Demographics, clinical presentation, angioarchitecture, and procedure-related complications were analyzed. Angiographic and clinical results were reported.ResultsSeventy-three patients, aged 40.5±17.8 years, were included. More than 60% of the patients presented with ruptured AVMs. Initial SM grades were I for 22% and II for 78% of the patients. Preprocedural modified Rankin Scale (mRS) score was 0–2 for 53 (72.6%), 3 for 12 (16.4%), 4 for 5 (6.8%) and 5 for 3 (4.1%) patients. Procedure-related morbidity was 2.7% and procedure-related mortality was 0%. Ninety percent (90.5%) of the patients were independent in their everyday lives (mRS score 0–2) at 6 months. In all but one case (95%) the embolization was curative.ConclusionStand-alone endovascular treatment for SM grade I and II brain AVMs seems safe and effective, allowing for complete obliteration of the nidus, with low complication rates. A study of larger cohorts is needed.

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We present results of a slip model from joint inversion of strong motion and static Global Positioning System data for the Mw7.1 Puebla‐Morelos earthquake. We find that the earthquake nucleates at the bottom of the oceanic crust or within the oceanic mantle with most of the moment release occurring within the oceanic mantle. Given its location at the edge of the flat slab, the earthquake is likely the result of bending stresses occurring at the transition from flat slab subduction to steeply dipping subduction. The event strikes obliquely to the slab, we find a good agreement between the seafloor fabric offshore the source region and the strike of the earthquake. We argue that the event likely reactivated a fault first created during seafloor formation. We hypothesize that large bending‐related events at the edge of the flat slab are more likely in areas of low misalignment between the seafloor fabric and the slab strike where reactivation of preexisting structures is favored. This hypothesis predicts decreased likelihood of bending‐related events northwest of the 2017 source region but also suggests that they should be more likely southeast of the 2017 source region.

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