Approach Considerations
Catheter spinal angiography remains the criterion standard for the diagnosis of Foix-Alajouanine syndrome and spinal dural arteriovenous (AV) fistulas. It may demonstrate specific arterial feeders and draining dorsal veins.
With regard to lab studies, obtain serum vitamin B-12 levels to exclude subacute, combined degeneration caused by vitamin B-12 deficiency. Vitamin B-12 levels should be normal in Foix-Alajouanine syndrome.
Consider testing for infections caused by human immunodeficiency virus (HIV), human T-cell leukemia virus type 1 (HTLV1), Lyme disease, and syphilis, as all can produce myelopathies.
Neurophysiologic studies such as somatosensory evoked potentials may be useful in evaluating Foix-Alajouanine syndrome. They may reveal a conduction block in the large fiber sensory system rostral to the lesion either at or below the sensory level.
Electromyography and nerve conduction studies can exclude a peripheral nerve lesion or motor neuron disease. Thus, they also can assist in the localization of the lesion to the spinal cord.
Imaging Studies
CT scanning and MRI
Computed tomography (CT) scanning and magnetic resonance imaging (MRI) studies may be normal during the early stages of Foix-Alajouanine syndrome.
With disease progression, T1-weighted MRI scans reveal swelling of the cord and decreased signal intensity peripherally within the affected spinal cord segments. On T2-weighted images, the spinal cord lesions are hyperintense in central locations.
Contrast administration often produces serpentine areas of enhancement and reveals the presence of enlarged, tortuous vessels in the subarachnoid space with associated "flow void" phenomena.
Most spinal dural AV fistulas occur in the thoracolumbar spinal cord; less than 6% are cervical or sacral in location. [7]
Angiography
Initially, MR angiograms can more correctly predict the site and extent of the fistula prior to the use of the more invasive technique of catheter angiography. MR angiograms generally demonstrate flow in serpentine perimedullary vessels.
As previously stated, catheter spinal angiography remains the criterion standard for the diagnosis of Foix-Alajouanine syndrome and spinal dural AV fistulas. It may demonstrate specific arterial feeders and draining dorsal veins.
Myelography
Myelographic studies are not required but may nonetheless be useful in Foix-Alajouanine syndrome. Irregular filling defects frequently are observed with myelography. Conventional CT myelography also may be useful.
Histology
Histologic findings include redundancy of veins within the cord and subarachnoid space. The dilated vessels have enormously thickened, hyalinized walls composed of abundant collagen and smooth muscle cells. Vascular thrombosis may be present. The gliotic spinal cord parenchyma beneath the dilated veins may show coagulative necrosis with exudation, fibrosis of the nerve roots, and ascending degeneration of the dorsal columns.
Proliferation of intramedullary blood vessels frequently is observed and may be accompanied by fibrinoid degeneration of the vessel walls. Hemosiderin deposition may be present, is predominantly perivascular, and is indicative of previous bleeding. (See the images below.) [4]
Photomicrograph of the cervical spinal cord region showing a thickened subarachnoid vein with a thrombotic occlusion (hematoxylin and eosin stain).
Photograph of the cervical spinal cord illustrating dilated, abundant subarachnoid veins (hematoxylin and eosin stain).
Photomicrograph of the cervical spinal cord region demonstrating several dilated, hyalinized intraparenchymal vessels (hematoxylin and eosin stain).
Photomicrograph of the cervical spinal cord depicting ischemic necrosis of the parenchyma (hematoxylin and eosin stain).
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Gross photograph of the dorsal surface of the spinal cord showing dilated and tortuous vessels.
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Photomicrograph of the cervical spinal cord region showing a thickened subarachnoid vein with a thrombotic occlusion (hematoxylin and eosin stain).
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Photograph of the cervical spinal cord illustrating dilated, abundant subarachnoid veins (hematoxylin and eosin stain).
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Photomicrograph of the cervical spinal cord region demonstrating several dilated, hyalinized intraparenchymal vessels (hematoxylin and eosin stain).
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Photomicrograph of the cervical spinal cord depicting ischemic necrosis of the parenchyma (hematoxylin and eosin stain).
