Rare entity presenting with onset of age of
approximately 50 years and characterized by a subacute myelopathy evolving
over 1 to 5 years. It is caused by an arteriovenous malformation of the
spinal cord predominantly affecting the lower thoracic and/or lumbosacral
Foix-Alajouanine Disease; Spinal Dural Arteriovenous
Fistula; Varicositas Medullae Spinalis.
Rare (no specific statistics). Male-to-female ratio of
4:1. No racial predilection.
Uncertain. Spinal dural arteriovenous
malformations may be acquired, although the specificity for the spinal cord
is not easily explained.
Not well understood. 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.
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.
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.
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).
Avoid central block procedures that can
break a preexisting delicate neurologic balance. Somatosensory evoked
potential intraoperative monitoring could be impossible because of coronal
lesion. Padding and positioning are critical, as it is for any paraplegic
As with other lower motor neuron
diseases, avoid succinylcholine (hyperkalemic cardiac arrests). The
sensitivity and duration of action of nondepolarizing drugs is markedly
increased. Must reduce the dose and monitor the neuromuscular junction.
Consider antibioprophylaxis and anticoagulant therapy. Steroid stress dose
if necessary. There are no indications that malignant hyperthermia occurs;
however, avoiding trigger anesthetic agents during the acute phase of
neuromuscular degeneration is recommended.
Cauda Equina Syndrome: Defined as low back pain, bladder and
bowel dysfunction, and variable lower extremity motor and sensory loss. Not
a genetic disorder but rather an ...