Clinical Features of Intracranial Dural Arteriovenous Fistulas with Spinal Perimedullary Venous Drainage: Report of Two Cases and Literature Review.

Objective: We describe two cases of myelopathy onset due to intracranial dural arteriovenous fistulas (DAVFs) and present a literature review.

Case presentation: (Case 1) A 44-year-old man with subacute onset myelopathy underwent an MRI and DSA. MRI showed T2-hyperintensity from the medulla oblongata to the cervical spinal cord with vascular flow voids, suggestive of a spinal DAVF. Unexpectedly, cerebral angiography revealed a tentorial DAVF. (Case 2) A 47-year-old man with progressive myelopathy underwent a head and spinal MRI. Head MRI and MRA were considered to be normal. Spinal MRI revealed T2-hyperintensity in the cervical spinal cord without obvious vascular flow voids around the spinal cord. Contrast-enhanced MRI showed a patchy gadolinium enhancement in the same spinal cord region with the enhancement of perimedullary vessels. Although myelitis was initially suspected, subsequently spinal DAVF was suspected because cervical CTA revealed abnormal spinal venous drainage. Unexpectedly, cerebral angiography identified a foramen magnum DAVF.

Conclusion: Regarding unexplained cervical myelopathy, even the absence of spinal cord surface vascular flow voids cannot necessarily exclude venous congestive myelopathy due to the DAVFs. In such cases, the contrast-enhanced MRI and cervical CTA are useful for visualizing abnormal vessels around the brain stem and the cervical spine. Especially, the co-presence of the abnormal vessels around the brain stem can suggest the intracranial DAVFs. Not only spinal DAVFs but also intracranial DAVFs should be considered as the differential diagnoses for venous congestive cervical myelopathy, in which cases cerebral angiography including carotid angiography is essential.