Abstract
A 24-year-old woman with hemorrhagic onset moyamoya disease received bilateral indirect bypass surgery 11 years ago. She presented with a life-threatening atraumatic acute right subdural hematoma with temporal lobe intracerebral hemorrhage due to a transdural anastomosis (TDA) aneurysm rupture. We reviewed six cases of rare TDA aneurysms, all of which occurred around the temporal base. TDA aneurysms may occur near the main trunk of the middle meningeal artery (MMA) where hemodynamic stress is high. Therefore, we must pay attention to skull base aneurysms that form near the MMA; otherwise, the prognosis would be poor if such an aneurysm ruptured.