Spinal Dural Arteriovenous Fistula: Symptoms

Overview

A spinal dural arteriovenous fistula (SDAVF) is an abnormal connection between arteries and veins in the dura covering over the brain or spinal cord. In an SDAVF, arteries and veins are directly connected to each other. The direct connection between artery and vein is called fistula. These fistulas vary in their size, location and the type of venous channel that they drain into. The spinal arteriovenous malformation may lead to sensory loss and motor weakness.

However, the causes of a spinal arteriovenous fistula are unknown. It is a rare pathology, occurring in less than 1 in a million people.

Causes

Spinal dural arteriovenous fistula is theoretically caused by abnormal blood flow between the dural artery, which supplies the dural root sleeve, adjacent spinal dura and the medullary vein, which drains into the coronal venous plexus.

But the exact cause of spinal dural arteriovenous fistula is not yet known. It is more common in men than in women, and most frequently in older adults (roughly from 50 to 60 years old). However, SDAVF can occur in younger age groups as well, including children.

Symptoms

The symptoms of SDAVF vary from people to people, depending on the location, size and type of the lesion. Some people with an SDAVF may even not have any obvious symptoms. These symptoms may develop slowly and steadily. Possible symptoms include:

  • Back pain, numbness, weakness
  • Difficulty walking or climbing stairs
  • Impairment in bladder or bowel function
  • Headache
  • Seizures
  • Stroke-like symptoms: The back up of blood in the venous circulation can compromise the normal flow of blood from the brain, leading to neurological symptoms similar to a stroke.
  • Bruit: It is an abnormal noise in the head, often described as wooshing sound.
  • Pulsatile tinnitus: It will cause a ringing in the ears and get louder with each heartbeat.
  • Swelling or redness of the eye: In some cases, the increased venous pressure can lead to this symptom, particularly with ones that drain into the cavernous sinus.

In addition, some dural arteriovenous fistulas can be asymptomatic. For some patients with very high venous pressures due to the fistula, the dilated veins or venous sinuses can even rupture and bleed, causing a hemorrhage around the brain and triggering acute deterioration in neurological function.

Symptoms may occur suddenly, including nausea, vomiting and a decreased level of consciousness.

Diagnosis

To diagnose a spinal dural arteriovenous fistula, doctors may recommend that patients conduct some diagnostic tests, which include:

  • MR (magnetic resonance) imaging scan. It uses large magnets, radiofrequencies, and a computer to produce detailed images of the spinal cord. However, an MR image does not reveal the location of the SDAVF, just effects on the spinal cord-like swelling and enlarged blood vessels which may be a sign of the SDAVF.
  • CT head scan. It can show fluid buildup caused by heightened cortical vein blood pressure as well as actual bleeding.
  • Angiography. Catheter-based cerebral angiography is the most reliable and definitive tool for SDAVF diagnosis. Angiogram will make it possible to identify the exact location of the fistula itself. In an angiogram, a radiologist injects a dye into the blood vessels.

Treatment

Generally, there are two major treatments for spinal dural arteriovenous fistula.

Some SDAVFs can be embolized or blocked through endovascular techniques. Usually the doctor will use a special glue which fills the blood vessel. The procedure is called endovascular embolization. The technique will pass a tiny catheter, or tube into the vessels feeding into the fistula. Once in place, the catheter releases a glue-like material or tiny particles that can seal off the fistula. However, this procedure may not be effective for some cases that have to do with blood flow and vessel anatomy.

If the patients have significant symptoms such as hemorrhage, surgery may be necessary. Using a surgical microscope and extremely fine instruments, neurosurgeons can microsurgically clip or separate the abnormal connection and restore the normal blood flow to the spinal cord.

If the fistula can be completely occluded, the fistula is generally considered cured and rarely recurs.


Keywords: Spinal Dural Arteriovenous Fistula.

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* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.