Cognard type IIa+b dural arteriovenous fistula presenting as a chronic subdural hematoma: A case report

Background: Dural arteriovenous fistula (DAVF) has been reported as a rare cause of chronic subdural hematoma (CSDH); however, CSDH associated with a Cognard type IIa+b DAVF has not been reported. Case Description: A 56-year-old woman without traumatic history presented with headache and was diagnosed with right-sided CSDH and a transverse-sigmoid sinus DAVF. She underwent transvenous and transarterial embolization along with burr-hole drainage. Although residual shunting persisted after the first session, complete resolution was achieved after the third. Over 4 years of follow-up, there was no recurrence of CSDH or DAVF. Conclusion: This case highlights that DAVFs can cause CSDH regardless of the Cognard type, and that combined curative DAVF treatment and drainage may be effective.