P056 Spontaneous and simultaneous bilateral middle meningeal arteriovenous fistula

<h3>Introduction</h3> Middle meningeal arteriovenous fistulas (MMAVFs) are defined as an abnormal connection between the middle meningeal artery and surrounding veins, most commonly resulting from head trauma. Spontaneous MMAVFs without head trauma history are extremely rare, with only 13 cases reported in English-language literature. Here, we present a case of spontaneous and simultaneous bilateral MMAVFs. <h3>Case Description</h3> A 37-year-old female patient was admitted with persistent pulsatile tinnitus with no history of head trauma, and physical examination showed no exophthalmos, bruit, chemosis, or cranial nerve palsy. Digital subtraction angiography revealed abnormal connections between MMA and middle meningeal vein on both sides. Upon readmission for treatment six days later, tinnitus had markedly improved during this short period. The right ECA angiogram showed non-visualization of MMAVF, suggesting spontaneous closure of fistula, which likely explained the improvement in the symptoms. With the superselection of left MMA using a microcatheter, fistula sac was packed beyond the damaged MMA wall, followed by partial embolization of the MMA to achieve complete obstruction of the abnormal connection. Post-procedural angiogram showed complete obliteration, and the patient was discharged without symptoms or neurological deficits. <h3>Results</h3> A trans-arterial approach can be used to deliver treatment in a safe and effective manner. While spontaneous closure is occasionally observed, it is not easily predictable, and considering treatment, particularly in cases accompanied by cortical venous reflux, appears to be a safe approach. <h3>Disclosure of Interest</h3> no.