Dural arteriovenous fistula at the foramen magnum presenting with subarachnoid hemorrhage: case reports and literature review

Background and purpose: Spinal dural arteriovenous fistulas (DAVFs) may arise at any level from the foramen magnum to the sacrum. Only a few case series of DAVFs at the foramen magnum have been reported, especially with patients presenting with subarachnoid hemorrhage (SAH). We performed a retrospective study of four such cases and summarize experiences in the diagnosis and surgical treatment of a DAVF at the foramen magnum. Methods: Four male patients, aged from 35 to 51 years, were admitted with severe headache. The cranial computerized tomography scans of all four patients showed SAH, with hemorrhage in the fourth ventricle with or without hemorrhage in the occipital horns of the lateral ventricles. Pre‐operative digital subtraction cerebral angiography showed a DAVF at the foramen magnum draining to medullary veins and/or the straight sinus and the confluence of sinuses. Two DAVFs were fed by the vertebral artery, whilst the others were fed by dural branches of the occipital artery and/or the ascending pharyngeal artery. Results: Three patients underwent direct microsurgical electrocoagulation and disconnection of the arteriovenous shunt via an enlargement of the foramen magnum and a hemilaminectomy at C1 by the far lateral suboccipital approach. Post‐operative angiography confirmed complete obliteration of the fistula. Conclusions: Cerebral digital subtraction angiography is an effective and accurate method for examination of a DAVF at the foramen magnum. It can be treated effectively and with minimal surgical trauma by microsurgical electrocoagulation and disconnection of the shunt.