Background: Cerebral dural arteriovenous fistulas (DAVFs) are vascular lesions consisting of a pathologic high-flow connection between dural arteries and veins or dural sinuses. Small DAVFs shunts have been demonstrated to exist physiologically, but as their estimated diameter is around 8-12 μm, they are not visible even on high-quality angiography studies. Case description: We report 2 cases of immediate development of a DAVF after embolization with microparticles of the middle meningeal artery for treatment of chronic subdural hematoma. Conclusions: This report represents the first description of sudden development of a DAVF after endovascular embolization of an intracranial artery and may shed light on the pathophysiology and development of DAVFs.