A Unique Type of Dural Arteriovenous Fistula at Confluence of Sinuses Treated with Endovascular Embolization: A Case Report
A 35-year-old male, who suffered from tinnitus in the right side since childhood, presented in emergency with a history of sudden and severe headache of two hours duration. There was no associated relevant history and he was alert and oriented. There was slight nuchal rigidity and bruit could be heard in the occipital region on both sides. Rest of the clinical examination was normal.\nComputed tomography scan done immediately showed diffuse subarachnoid haemorrhage (SAH) along the inferior surface of the tentorium. Magnetic resonance imaging (MRI) showed abnormal flow voids just anterior to the torcula and in the left cerebellar hemisphere. There were many dilated veins connecting these flow voids. There was no associated infarct or edema in the brain parenchyma ().\nIntracranial angiogram revealed a DAVF adjacent to the confluence of venous sinuses and an associated large focal venous ectasia (varix) near the torcula (). It was supplied from carotid vessels and vertebral arteries. The main feeders were from both of occipital, ascending pharyngeal, middle meningeal and posterior meningeal arteries. These feeders converged into a big varix just anterior and to the right of the confluence and had two drainage outlets. The retrograde flow or reflux wandered into the left cerebellar cortical veins and multiple varices formation in the left cerebellar hemisphere whereas the other was an antegrade flow into the dominant right transverse sinus via a small channel.\nThe patient was initially managed in another hospital by endovascular procedure for flow reduction, where the main feeders were palliatively embolized using particles via the transarterial route. Feeders from right occipital, right middle meningeal and left occipital arteries were embolized and the main residual feeder was the left ascending pharyngeal artery. The patient's symptom was improved and his tinnitus reduced in intensity. Since there was a significant residual lesion, the patient was referred to our hospital for complete obliteration of the fistula.\nTransvenous embolization (TVE) was performed through the transfemoral approach six weeks after the first procedure. The procedure was performed under local anaesthesia and moderate sedation with Propofol (Diprivan, AstraZeneca K.K., Osaka, Japan). A coaxial system was used to cannulate the transverse sinus. A 6 Fr, 90 cm guiding sheath (Shuttle-SL; Cook, Bloomington, IN, USA) and 6 Fr, 100 cm, curved tip guiding catheter (Envoy MPC, Cordis, Miami, FL, USA) were placed in the internal jugular vein. Through this 6 Fr guiding catheter, a 4 Fr, 125 cm guiding catheter (Cerulean G, Medikit, Tokyo, Japan) was placed in the right transverse sinus (). The Excelsior 1018 Microcatheter (Boston Scientific, Natick, MA, USA) was carefully placed at the origin of the left cerebellar cortical vein. The preferential and rapid flow into the refluxed vein helped us to easily direct the tip of the microcatheter. The distal end of this vein was occluded with 8 coils of various sizes from different companies. Complete obliteration of flow to the cerebellar varices was obtained (). Then the main varix was filled with 26 coils with an aim to block all the shunt points ().\nIn spite of dense packing seen on imaging, there were residual shunt points which allowed the flow of arterial blood into the transverse sinus. Booster transarterial embolization with polyvinyl alcohol (PVA) particles and microfibrous collagen was then performed through the left external carotid artery (ECA). A complete occlusion of DAVF could be achieved ().\nThe postoperative period was uneventful. The symptom of tinnitus was entirely disappeared. MRI acquired 5 days after procedure showed thrombosis of the all the varices and cerebellar cortical vein without any edema or infarction ().