A 69-year-old man consulted our department regarding further examination because cerebrovascular abnormalities were accidentally found during a medical checkup of the brain (brain dock). He did not have any history of head trauma or hypertension. Physical examination yielded completely normal results. Magnetic resonance imaging during the brain dock revealed anomalous venous ectasia of BVR (Fig. 1). Subsequent catheter angiography revealed a DAVF in the left sphenoid wing; the fistula was supplied by direct collateral from ethmoidal branches of the ophthalmic artery ( Fig. 2A) and MMA (Fig. 2B). Venous drainage from the fistula mainly consisted of a large collector vein located in the temporal tip (referred to as BATV), draining in an anterograde manner into the BVR and subsequently into the vein of Galen ( Fig. 2A, B). Some part of the venous drainage from BATV flowed into the deep middle cerebral vein (DMCV), refluxed into SMCV in the capillary phase, and finally flowed into the cavernous sinus (CS; Fig. 2C). Considering the angiography findings, the venous route may not have been accessible for transvenous embolization (TVE), and the risks of incomplete obliteration or damage to the central retinal artery that are associated with transarterial embolization (TAE) should not be ignored. This lesion may be easily accessible by a usual craniotomy procedure. We decided to proceed with open surgery rather than the endovascular approach. A left-sided frontotemporal craniotomy A 69-year-old man consulted our department regarding further examination because abnormal venous ectasia of the basal vein of Rosenthal (BVR) was accidentally found on magnetic resonance imaging. Angiography revealed a dural arteriovenous fistula (DAVF) in the left sphenoid wing; the fistula was supplied by the ophthalmic artery and the middle meningeal artery. Venous drainage from the fistula consisted of a large collector vein located in the temporal tip, which drained into the BVR. We selected open surgery because this lesion may be difficult to access and is associated with significant risks through an endovascular approach. After temporal clip ligation of the drainer, the superficial middle cerebral vein became the main drainage route directly in connection with the fistula. Therefore, both were ligated, after coagulation of feeding arterial networks on the dura around the sphenoid wing. The patient experienced no complications from the surgical procedure, and postoperative angiography demonstrated obliteration of the fistula. DAVF in the sphenoid wing with deep drainage is believed to carry a high risk of hemorrhage or venous infarction because of the presence of Galenic drainage, varix, and cortical venous reflux. Treatment is strongly recommended even if the symptoms are minimal. Open surgery appears to be safe and often the best therapeutic option.