Foramen Magnum Dural Arteriovenous Fistulas: Clinical Presentations and Treatment Outcomes, A Case-Series of 12 Patients.

BACKGROUND: Dural arteriovenous fistulas (DAVFs) are usually seen in relation to the venous sinuses, but in certain rare instances fistulas may not drain directly into the venous sinuses but rather drain into the cortical veins. This rare form of DAVF may present with either intracranial hemorrhage or myelopathy. The mode of clinical presentation is influenced by the venous outflow into either intracranial drainage or caudally intraspinal drainage.

OBJECTIVE: To evaluate the clinical presentations, angioarchitectural characteristics, and treatment of 12 patients who presented with DAVF in the region of the foramen magnum.

METHODS: In this case series we reviewed clinical charts, radiological images, and operative notes of 12 patients who were diagnosed of foramen magnum DAVF from December 1993 until April 2017. The angiographic studies were analyzed for feeding arteries, the location of the shunt, the venous drainage patterns, and the presence of venous side aneurysms.

RESULTS: Twelve patients were angiographically confirmed with foramen magnum DAVFs. They included 11 males and 1 female (M:F = 11:1). Mean age of 55.6 yr ranging between 42 yr and 71 yr of age. Eight patients presented with progressive myelopathy, 3 patients with posterior fossa intracranial hemorrhage, and 1 patient presented with lower cranial nerve IX and XII palsies due to mass effect.

CONCLUSION: A dural arteriovenous shunt, which may be located in the region of the foramen magnum, should be suspected in those cases of subarachnoid hemorrhage in the posterior fossa or progressive myelopathy mimicking spinal DAVF.