Dural arteriovenous fistula on the convexity presenting with pure acute subdural hematoma

Non-traumatic dural arteriovenous fistula/malformation (dural AVF/AVM) presenting with pure subdural hematoma (SDH) is relatively rare. We report on a male patient who showed pure acute SDH and was diagnosed as having dural AVF on the convexity near the superior sagittal sinus (SSS), based on angiographic findings. A 27-year-old man was admitted to our hospital due to headache with acute onset. The patient did not have a history of head trauma or injury. Head CT showed an abnormal high-density area on the surface of the cerebral hemisphere on the left side, indicating acute SDH. Angiography during the arterial phase demonstrated that an abnormal artery originating from the left occipital artery was connected with a dural vein and a diploic vein on the convexity near the SSS. We concluded that a dural AVF existed at this area, and that the dural AVF had caused the acute SDH. Dural AVF/AVM which causes non-traumatic SDH is usually accompanied by intracerebral hemorrhage (ICH) and/or subarachnoid hemorrhage (SAH). In contrast, non-traumatic dural AVF/AVM presenting with pure SDH is rare, and our patient represents such a rare case. We should consider dural AVF/AVM and perform angiography if necessary when we encounter a patient showing non-traumatic SDH without ICH and/or SAH.