Dural Arteriovenous Fistula Involving an Isolated Sinus Treated Using Transarterial Onyx Embolization
A 69-year-old woman with a two-year history of dizziness and headache was admitted to our hospital after experiencing a generalized tonic clonic seizure. Her clinical examination was normal. She had no history of head trauma. However, six years previously she had undergone a right suboccipital craniectomy and microvascular decompression (MVD) of the facial nerve for a hemifacial spasm. A computed tomography scan obtained at the time of her initial presentation showed curvilinear subcortical calcification and sulcus effacement, predominantly in the right temporal lobe (). Susceptibility-weighted magnetic resonance imaging (SWI) then demonstrated multiple curvilinear flow voids along the cerebral surface, thus suggesting the presence of a vascular anomaly. Magnetic resonance angiography (MRA) performed to evaluate the possibility of a vascular lesion, revealed a DAVF of the isolated right transverse sinus as well as cortical venous reflux (). Digital subtraction angiography (DSA) demonstrated a DAVF with an isolated right transverse sinus, supplied by the transosseous branches of the bilateral occipital artery, and the petrosquamous branch of the right middle meningeal artery as well as dural branches from the right vertebral artery. There was retrograde cortical venous reflux (CVR) via leptomeningeal veins from the temporal lobe (). Due to our fear of the risk of hemorrhage or venous infarction associated with CVR, we decided to perform endovascular treatment of the DAVF. Intervention was performed with the patient under general anesthesia. An intravenous bolus of 4000 IU of heparin was administered following placement of a 6-French guiding sheath in the right femoral artery. We initiated the embolization procedures using superselective catheterization of the larger arterial pedicle, which supplied the isolated sinus of the DAVF, in order to achieve the arteriovenous shunt point. A 6-French guiding catheter (Envoy, Cordis Endovascular, Miami Lakes, FL, USA) was placed at the origin of the external carotid artery supplying the meningeal artery chosen for DAVF catheterization. A Marathon microcatheter (ev3 Inc., Plymouth, MN, USA) was then navigated coaxially to access the DAVF under road map (). The microcatheter lumen was then flushed with dimethyl sulfoxide (DMSO, ev3 Inc., Plymouth, MN, USA). After that, 0.3 mL Onyx-18 was injected within DAVF followed by biplanar simultaneous subtracted fluoroscopy. During the injection of Onyx, special attention was given in order to maintain a steady injection of Onyx, while looking for any reflux of Onyx into the feeding artery along the microcatheter as well as into the cortical vein beyond the isolated sinus. When unwanted flow into a non-targeted areas was observed, the injection was stopped for as long as two minutes. Once the affected sinus was completely packed with Onyx and there was reflux into the feeding artery along the microcatheter, the injection was terminated. The microcatheter was gently pushed back and could then be removed without any complications. Post-embolization angiography showed very slow flow to the right transverse sinus from the occipital artery, and with sequential contrast filling in the right middle meningeal artery, although without evidence of an arteriovenous shunt with early cortical venous drainage (). The total duration of the Onyx injection was 21 minutes, including eight pauses for reflux. The total procedure time from puncture of the femoral artery to closure of the puncture site was 60 minutes. The patient was discharged five days later and her postoperative course was uneventful. During the next four months, the patient was symptom-free and follow-up magnetic resonance imaging was then scheduled.