Foix–Alajouanine syndrome

Overview

Foix–Alajouanine Syndrome is a rare neurological condition characterized by progressive myelopathy (spinal cord dysfunction) resulting from a spinal dural arteriovenous fistula (SDAVF). The syndrome was first described by French neurologists Charles Foix and Théophile Alajouanine in the 1920s. It involves abnormal blood vessels in the spinal dura mater, leading to impaired venous drainage, spinal cord congestion, and eventual ischemia. The condition often presents with gradual onset of weakness, sensory changes, and bladder or bowel dysfunction.

Causes

Foix–Alajouanine Syndrome is caused by a spinal dural arteriovenous fistula (SDAVF), which is an abnormal connection between an artery and a vein in the dural covering of the spinal cord. This fistula results in high-pressure arterial blood being shunted directly into the venous system, causing venous hypertension. The increased pressure and impaired drainage lead to spinal cord edema, ischemia, and progressive neurological deficits.

While the exact cause of the formation of SDAVFs is unknown, it is considered an acquired condition and is more common in older adults, particularly men.

Symptoms

Symptoms of Foix–Alajouanine Syndrome usually develop gradually over months or even years and are often misdiagnosed due to their nonspecific nature. Common clinical features include:

• Progressive lower limb weakness: Often starting with mild weakness or stiffness and advancing to paralysis.

• Gait disturbances: Due to motor dysfunction and spasticity.

• Back pain: Localized or radiating along the spine.

• Sensory disturbances: Numbness, tingling, or loss of sensation, especially in the legs or perineum.

• Urinary and bowel dysfunction: Incontinence or retention due to autonomic involvement.

• Sexual dysfunction: In some cases.

Diagnosis

Early diagnosis is critical to prevent irreversible spinal cord damage. The following steps are commonly used to diagnose Foix–Alajouanine Syndrome:

• Magnetic Resonance Imaging (MRI): Shows spinal cord swelling, serpentine flow voids indicating dilated veins, and possible cord signal changes.

• Spinal angiography: The gold standard for diagnosis. It identifies the precise location and anatomy of the arteriovenous fistula.

• Neurological examination: To assess motor, sensory, and autonomic function deficits.

• Lumbar puncture: May reveal elevated protein in cerebrospinal fluid (CSF), although not diagnostic.

Treatment

Treatment of Foix–Alajouanine Syndrome aims to obliterate the fistula and restore normal spinal cord perfusion. Options include:

• Microsurgical ligation: Surgical closure of the fistula is often curative and preferred when anatomy is favorable.

• Endovascular embolization: A less invasive technique using a catheter to block the fistula with coils or glue-like materials. Suitable in selected cases, though recanalization can occur.

• Rehabilitation therapy: Physical and occupational therapy to improve mobility and manage long-term effects.

• Pain management: Medications may be needed for chronic back pain or neuropathic pain.

Prognosis

The prognosis of Foix–Alajouanine Syndrome depends on the timing of diagnosis and treatment. If treated early, especially before significant neurological decline, patients may experience substantial improvement or stabilization of symptoms. However, delayed treatment can lead to permanent spinal cord damage and irreversible paraplegia or incontinence. Lifelong follow-up may be necessary to monitor for recurrence or manage residual deficits.