Dural arteriovenous fistula

Dural arteriovenous fistulas (DAVFs) are pathologic vascular connections that shunt dural arterial flow directly to dural venous drainage.

DAVFs comprise 10–15% of all intracranial AVMs ¹⁾. 61–66% occur in females, and patients are usually in their 40 s or 50 s. They occur rarely in children, and when they do they tend to be complex, bilateral dural sinus malformations ²⁾

Dural arteriovenous fistulas can occur at any dural sinus but are found most frequently at the cavernous or transverse sinus.

Intracranial dural arteriovenous fistula.

Spinal dural arteriovenous fistula.

The etiology and pathophysiology of DAVFs is not fully understood. Several hypotheses for development of DAVF and classifications for predicting risk of hemorrhage and neurological deficit have been proposed to help clinical decision making according to its natural history ³⁾.

Iatrogenic complications such as pseudoaneurysms formation or dural arteriovenous fistulas (dAVFs) formation-has been identified in rare cases after the surgical intervention for revascularizations. We describe two cases. In first case, the patency of the anastomosis site was good and saccular type pseudoaneurysm formation was found at parietal branch of posterior middle meningeal artery (MMA) in transfemoral cerebral angiography (TFCA) performed on the twelfth day after surgery. We decided to treat pseudoaneurysm by endovascular embolization the next day, but the patient was shown unconsciousness and anisocoria during sleep at that day. Computed tomography showed massive subdural hemorrhage at the ipsilateral side, thus we performed decompressive craniectomy and hematoma evacuation. In second case, the patency of the anastomosis site was good and dAVF formation at right MMA was found in TFCA performed on the sixth day after surgery. They performed endovascular obliteration of the arteriovenous fistula under local anesthesia. Pseudoaneurysm formation or dAVF formation after revascularization surgery is an exceptional case. If patients have such complications, practioner should carefully screen the patients by implementing digital subtraction angiogram to identify anatomic features; as well as consider immediate treatment in any way, including embolization or other surgery ⁴⁾.

Radical treatment is to obliterate the draining veins in any treatment modalities including endovascular treatment or surgical treatment. Radiosurgery is the last choice. Transvenous embolization plays the main role in the DAVF of the cavernous sinus and anterior condylar confluence. Transarterial embolization with Onyx has dramatically improved the obliteration rate of the transverse-sigmoid, superior sagittal sinuses, and other non-sinus lesions. Transarterial NBCA injection is still the gold standard in the endovascular treatment of the spinal dural and epidural AVFs. Understanding of the functional microvascular anatomy is mandatory, especially in the transarterial liquid injection (Onyx and NBCA). Surgical treatment in the DAVF of the anterior cranial base, craniocervical junction, tentorial region, and spine is a safe and radical treatment. Postoperative follow-up is necessary from the viewpoint of chronological and spacial multi-occurrence of this disease ⁵⁾.