Two Cases of Idiopathic Middle Meningeal Arteriovenous Fistula Initially Diagnosed by Magnetic Resonance Angiography.

Reports of middle meningeal arteriovenous fistula (MMAVF) are relatively rare, and reports of idiopathic MMAVF are extremely rare. In the past, diagnoses of MMAVF have been confirmed by cerebral angiography, but magnetic resonance angiography (MRA) resolution is improving. Here, we report two cases of idiopathic MMAVF that were diagnosed by unreconstructed time-of-flight MRA (MRA-TOF) and successfully treated by trans-arterial embolisation with endovascular treatment. Both patients suffered from pulsatile tinnitus, and MRI was performed. Two dilated vessels were revealed in the middle temporal fossa by unreconstructed MRA-TOF imaging. These dilated vessels were thought to be the middle meningeal artery and middle meningeal vein; therefore, we diagnosed both patients with MMAVF. Following angiography, both patients had coil embolisation with endovascular treatment, and their conditions improved. In cases of idiopathic MMAVF without a history of trauma, brain surgery, or endovascular surgery, unreconstructed MRA-TOF may be useful as a primary diagnostic tool, and endovascular treatment before bleeding may produce better outcomes.