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At a glance

Rare entity presenting with onset of age of approximately 50 years and characterized by a subacute myelopathy evolving over 1 to 5 years. Foix-Alajouanine Syndrome is an arteriovenous (AV) malformation of the spinal cord predominantly affecting the lower thoracic and/or lumbosacral levels. Cervical cord involvement is rare. Findings include necrosis of the affected cord regions. Grey matter structures are more severely involved than white matter.

Synonyms

Foix-Alajouanine Disease; Spinal Dural Arteriovenous Fistula; Varicositas Medullae Spinalis Congestive Myelopathy Syndrome.

Incidence

Rare (no specific statistics). Male-to-female ratio of 4:1. No racial predilection.

Genetic inheritance

Uncertain. Spinal dural arteriovenous malformations may be acquired, although the specificity for the spinal cord is not easily explained.

Pathophysiology

Although not well understood, it is associated with masses of enlarged, tortuous, thick-walled subarachnoid veins are observed overlying the surface of the cord (primarily on the posterior aspect). Smaller blood vessels with thickened fibrotic walls also are present within the affected spinal cord segments. In most cases there is an arteriovenous fistula in the lower thoracic dura, resulting in increasing the pressure within the dura, compromising perfusion, and leading to iterative infarction of the spinal cord parenchyma. Thrombosis may occur, but venous stasis is probably the primary cause of infarction. Proliferation of intramedullary blood vessels is frequently observed and may be accompanied by fibrinoid degeneration of the vessel walls. Another proposed mechanism is that remittent leakage of blood from the arteriovenous malformation promotes progressive adhesive arachnoiditis resulting in iterative “chokes” of the spinal cord. The same mechanism has been evocated to be possible when blood patches are realized.

Diagnosis

On MRI, T1-weighted images show decreased signal intensity within the affected spinal cord segments; the lesions are hyperintense on T2-weighted images. Contrast administration usually produces serpentine areas of enhancement. Spinal angiography is the definitive diagnostic procedure for evaluation of this disease.

Clinical aspects

Onset between 20 and 60 years of age (usually a male who is older than 50 years). Progressive paraplegia (manifested as increasing weakness and numbness or tingling in the lower extremities, frequent falls), urinary and fecal incontinence, and nonradiating lower back pain. Affected patients initially are spastic but eventually develop flaccid paralysis of the limbs and may become wheelchair bound. Four different types of arteriovenous malformation have been described: dural arteriovenous fistulas, glomus malformations, juvenile type arteriovenous malformations, and intradural extramedullary arteriovenous fistulas.

Precautions before anesthesia

Corticotherapy is often prescribed: evaluate sodium and potassium status. If angiographic evidence of thrombosis exists, anticoagulation with heparin is indicated. Evaluate neurologic function (history, clinical, CT, MRI).

Anesthetic considerations

Avoid central block procedures that can break a preexisting delicate neurologic balance. Somatosensory evoked potential ...

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