Vascular Malformations

      Spinal arteriovenous (AV) malformations can be dural or intradural. The dural variety is much more common (80% of cases) and most often occurs in the lower thoracic and lumbar regions. A low-flow fistula in the dura adjacent to a nerve root is supplied by a dural artery and drains into a medullary vein, causing venous congestion and ischemia of the spinal cord. Intradural AV malformations can be intramedullary or pial, are fed by the anterior spinal artery, and present with cord hemorrhage.

      The intramedullary component of intradural AV malformations is generally readily visible on MR images. Serpiginous flow voids and focal cord enlargement may highlight the site of the nidus. Blood products from episodes of hemorrhage often give these lesions a heterogeneous texture. High signal on T2-weighted images adjacent to the nidus may represent edema, ischemia, or gliosis. Endnote The intramedullary component usually enhances with gadolinium.

      The dural AV malformations are more of a challenge. Diagnosis is often dependent on visual-izing the dilated veins on the surface of the cord. Sagittal T2-weighted images may show irregularity of the cord surface, but flow artifacts can be problematic. A more reliable technique is a rapid set of sagittal T1-weighted images following a bolus injection of gadolinium. The flow within the draining veins is sufficiently slow to allow for intravascular enhancement. Endnote  

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