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Patient 4: Woman with months of bilateral low back and buttock pain, now with leg weakness and difficulty voiding.

Spinal dural AV fistula supplied by a branch of the lateral sacral artery from left internal iliac artery communicating with an intradural venous plexus extending to level of conus medullaris.

Age: 40-50 year and older population

Sex: 85% male predominance

Anatomy: Usually a single arteriovenous communication within the dura

usually close to an intervertebral foramen

On the dorsal aspect of the nerve root near the axilla of the dural sleeve.

Arterial supply: 1 or 2 dural branch(es) of the radiculo-medullo-dural artery

Venous drainage: usually  through a single engorged tortuous draining medullary vein

Supplying the coronal venous plexus

usually largest and most numerous vessels are along the dorsal surface of the spinal cord

Site: Thoracic or lumbar distribution.

Venous hypertension with subsequent necrotizing myelopathy

Coagulative or liquefactive necrosis

Thickening and hyalinization of the walls of the medullary veins

Non-specific but most common cause is venous hypertension (Foix-Alajouanine syndrome)

Long standing

neocapillary formation within the cord

atrophy.

Clinical:

Slowly progressive myelopathy characterized by leg weakness with bladder and bowel dysfunction

Maneuvers that increase venous pressure (e.g., valsalva and exercise) exacerbate symptoms

Critical to diagnose

Treatable disease with possibility for partial recovery.

Focal or segmental enlargement of the cord

Increased parenchymal T2 signal

Representing edema and necrotizing myelopathy

Enhancement

Parenchymal

Within veins along posterior surface

Abnormal scattered vascular flow voids adjacent to the cord representing a dilated coronal venous plexus.

Spinal SAH

Acute or subacute hemorrhage within the cord

Myelomalacia and atrophy in long standing cases.

Myelogram: 

Serpiginous filling defects, usually over the dorsal surface of the cord.