A Pure Acute Subdural Hematoma Presenting with a Diploic Arteriovenous Fistula: Case Report and Literature Review

OBJECTIVE: We report a case of pure acute subdural hematoma (SDH) caused by a diploic arteriovenous fistula (AVF) and it is a first case report as far as we researched it. CASE PRESENTATION: A 19-year-old man was admitted as an emergency to our hospital with headache and nausea. CT scan on hospital admission showed a right acute SDH. Because there was no history of head trauma, MRI, MRA, and DSA were performed to identify a source of bleeding. DSA disclosed an AVF. The shunt was located between a frontotemporal branch of the middle meningeal artery (MMA) and a diploic vein, and its shunting point formed an aneurysmal sac, which was considered to have ruptured. Endovascular treatment was administered rather than surgical treatment to prevent re-bleeding because the patient was conscious and alert, CT showed a small SDH, and the left MMA near the shunting point was accessible for catheterization. A diluted mixture of 25% n-butyl-2-cyanoacrilate was injected into a left frontoparietal branch just before the shunting point and the shunt, including the aneurysmal sac, was obliterated. The patient’s postoperative course was uneventful and he was discharged without neurological deficits. CONCLUSION: We experienced a patient with a pure acute SDH caused by diploic AVF. In patients with non-traumatic acute SDH, DSA is recommended to determine its underlying cause. Our review of published reports yielded few instances of non-traumatic pure acute SDH in young people. Possible causative factors should be investigated promptly and appropriate treatment provided immediately.