Foix-Alajouanine Syndrome
Foix-Alajouanine syndrome, also called subacute ascending necrotising myelitis, results from chronic congestion of the extrinsic pial veins of the spinal cord and of the intrinsic subpial network. It is characterised by progressive ascending deficit over a period of several months or years.
Epidemiology
The prevalence is unknown. The syndrome most commonly affects men over the age of 50.
Clinical description
The initial symptoms are variable and include dysesthesia of the inferior members (symmetrical in most cases) associated with progressive ascending motor deficit. The ascending paraplegia eventually leads to urinary incontinence. Unilateral or painful manifestations at presentation are rare but have been reported.
Etiology
The causative lesion is a dural arteriovenous shunt of the medullary emissary vein. The arteriovenous shunt is acquired. It is fed by branches of the spinal meninges. The shunt is associated with reflux into the venous drainage of the cord, leading to congestion and chronic medullary ischemia.
Diagnostic methods
Radiological investigations and magnetic resonance imaging (MRI) of the spinal cord reveal dilated perimedullary veins associated with a hypersignal from the interior of the cord and, in chronic forms, variable degrees of spinal cord atrophy. Medullary angiography may be used to identify the arteriovenous shunt zone.
Management and treatment
Endovascular treatment is possible in around two thirds of cases. In the remaining cases, surgical disconnection of the emissary vein from the shunt zone leads to resolution of the fistula. In 80% of cases, improvement is immediate and symptoms regress progressively in a manner that is chronologically inverse to that of their appearance. In more evolved cases, no improvement is obtained. In some rare forms, secondary thrombosis may occur, aggravating the preoperative clinical manifestations. Early diagnosis of the disease allows more effective treatment. The most severe forms are most often associated with delayed diagnosis.