Subarachnoid hemorrhage with concurrent dural and perimedullary arteriovenous fistulas at the craniocervical junction: A case report and literature review.

BACKGROUND: The association between a dural arteriovenous fistula (dAVF) perimedullary arteriovenous fistula (AVF) is rarely observed at the cranio-cervical junction (CCJ). We present a case of subarachnoid hemorrhage (SAH) with concurrent dAVF and perimedullary AVF at the CCJ. Here, we describe the cause of bleeding and the process of determining whether it was a varix or an arterial aneurysm. CASE DESCRIPTION: A 69-year-old man with SAH visited the emergency department. A dAVF at the CCJ was detected on digital subtraction angiography (DSA). However, after 3 weeks, when the DSA was repeated, a perimedullary AVF and varix were identified. We performed an endovascular treatment, but because the perimedullary AVF remained, we performed a direct surgery. The patient was discharged without weakness, but this left abducens nerve palsy remained. CONCLUSIONS: In recent reports, SAH caused by concurrent dAVF and perimedullary AVF raised the possibility of an arterial aneurysm. However, in this case, the possibility of venous bleeding was high and a varix rather than an aneurysm was observed, On the basis of the reported cases, concurrent dAVF and perimedullary AVF at the CCJ is a "middle-flow arteriovenous shunt" that may induce a varix or an arterial aneurysm.