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.