There are several types of spinal blood vessel malformations. These include:
- Spinal AVM (arteriovenous malformation) .This is an abnormal tangle of blood vessels within the spinal cord itself. It is similar to an AVM in the brain.
- Spinal dural AVF (arteriovenous fistula). This is the most common type of spinal malformation. It typically occurs in older males, usually in the lower part of the spinal cord. The fistula is a direct connection between an artery and a vein that drains the spinal cord. It is located in the dura surrounding a nerve root from the spinal cord. It produces symptoms by increasing the pressure in the vein, which congests the blood flow in the spinal cord.
- Spinal peri-medullary fistula. This is a direct connection between an artery and vein on the surface of the spinal cord.
Signs and symptoms
Spinal arteriovenous fistulas generally become symptomatic over time. They are usually a result of increasing venous hypertension. This prevents blood from draining out of the spinal cord. It alters spinal cord function by creating edema (swelling) due to the congested blood flow. Symptoms may include:
- Leg weakness, tingling, numbness or burning
- Pain in the back or legs
- Changes in bowel and bladder function
- Difficulty walking
Diagnosis of a spinal fistula starts with a physical exam and medical history. Concern for a spinal cord problem generally leads to an magnetic resonance imaging (MRI) scan of the spine. Edema may be seen in the spinal cord or abnormally large vessels may be identified. The definitive test is a spinal angiogram . Other tests that may be utilized include spinal CT, MR angiography or a myelogram .
The goal of treatment is to prevent worsening of symptoms. Although symptoms may improve when the fistula is treated, there is no guarantee. If you have a spinal fistula, several options may be considered. Depending on your clinical condition, your preferences and the location of the fistula, these may include:
- Observation may be considered if there are minimal or no symptoms, or if the risks associated with treatment are too high. Often, treatment for a spinal dural AVF is recommended because of the significant risk for progression of symptoms.
- Embolization. This is a minimally invasive neuro-interventional procedure. Using x-ray guidance, a small catheter (tube) is directed through the blood vessels to the location of the fistula. A special glue is injected to seal off the fistula from the inside. The advantage of embolization is that it does not require surgery. However, sometimes the fistula cannot be reached. There is also a chance that the fistula can recur.
- Spinal fistula disconnection surgery. This procedure is performed to block this connection to prevent further damage and allow the spinal cord to heal. An incision is made in the middle of the back over this area and the muscles are lifted off the bones of the spine. The back of the spinal canal, called the lamina, is removed at one or more levels. The spinal fluid sac is then opened. Using a microscope, the fistula is found where it comes into the spine, and a small clip is placed on it. Another angiogram is done showing that blood is not going the wrong way into the spinal cord anymore. The fistula is then cut, the sac of spinal fluid is sewn shut, and the back muscles and skin are closed with stitches and/or staples. Sometimes the bone (the lamina) are reattached with small plates and screws, as well.