Spinal aneurysms

What is a spinal aneurysm?

A spinal aneurysm is a weak, bulging area in one of the small blood vessels that supply the spinal cord. It's rare, and if it bursts, it can cause bleeding around the spinal cord.

What are the symptoms of a spinal aneurysm?

Symptoms usually start suddenly. The most common are:

• severe back pain, which can spread quickly to other areas
• a sudden, severe headache, particularly if the bleeding tracks up towards the brain
• weakness, numbness or pins and needles in your legs, or sometimes your arms
• new problems controlling your bladder or bowel.

If the bleeding is significant, it can lead to sudden weakness or paralysis below the level of the affected blood vessel.

What are the causes of spinal aneurysms and who is at risk?

Doctors think most spinal aneurysms develop when the wall of a small artery supplying the spinal cord splits or tears, in a process called dissection. Why this happens usually isn't clear, but possible triggers include repeated vomiting or straining, a slipped disc pressing on the artery, long-term high blood pressure, smoking, and connective tissue or inflammatory conditions.

Some spinal aneurysms are linked to other blood vessel conditions, such as a spinal vascular malformation, narrowing of the aorta, or blockages in the arteries supplying the spine. When there's no such underlying condition, doctors call it an "isolated" spinal aneurysm.

Spinal aneurysms are rare at any age, but on average affect people in their fifties, and happen roughly twice as often in women as in men.

Are there different types of spinal aneurysm?

Spinal aneurysms are usually grouped by which blood vessel is affected:

• Anterior spinal artery aneurysms, including those on the radiculomedullary artery, affect the vessel supplying the front of the spinal cord. These carry a higher risk if they block off, since this can cut off blood supply to the cord.
• Posterior spinal artery aneurysms, including those on the radiculopial artery, affect the vessel supplying the back of the spinal cord. Blockage here is usually well tolerated, so the main risk is from bleeding rather than lost blood supply.
• Lateral spinal artery aneurysms are less common and affect a side branch of the spinal blood supply.

Most spinal aneurysms are described as "fusiform", meaning the artery balloons out evenly along a stretch, which fits with them being caused by a split in the artery wall. A smaller number are "saccular", a rounder, berry-like bulge that may have a different underlying cause.

Spinal aneurysms are also described as "isolated" when they occur on their own, or as linked to another vascular condition, such as a spinal vascular malformation, when they occur alongside one.

How are spinal aneurysms diagnosed?

An MRI scan is usually the first test and may show a build-up of blood around the spinal cord. However, the aneurysm itself is often too small to see clearly on MRI, so a spinal angiogram, an X-ray test that maps the blood vessels using a dye, is usually needed to confirm the diagnosis.

Because spinal aneurysms are so rare and small, this angiogram is best carried out and reviewed by a specialist experienced in this type of imaging, as they can be easy to miss.

How are spinal aneurysms treated?

Treatment depends on which artery is affected, where the aneurysm sits, and how unwell you are when you're diagnosed. There's no single standard approach, and your specialist will weigh up the risks and benefits of each option for your particular case.

Non-surgical (conservative) treatment

Because spinal aneurysms are so small, and often heal by themselves, many are simply monitored with repeat scans rather than treated directly. In one study of over 100 published cases managed this way, around three-quarters improved, with the aneurysm often disappearing completely on follow-up imaging.

Conservative management is particularly likely to be recommended for aneurysms on the artery supplying the front of the spinal cord, since treating these directly carries a higher risk of cutting off blood supply to the cord than simply monitoring is thought to carry from further bleeding.

Surgical and endovascular treatment

If treatment is needed, this usually means either open surgery or an endovascular procedure, where instruments are guided through the blood vessels rather than through an open incision.

Surgery, most often to remove the aneurysm, is the most commonly used treatment overall and tends to have a lower complication rate. It's usually recommended if you need decompression because of pressure on your spinal cord, or if the aneurysm is difficult or unsafe to reach using blood vessels alone.

Endovascular treatment blocks off the aneurysm from inside the blood vessel, using tiny coils, glue, or other materials. It's often used for aneurysms on the artery supplying the back of the spinal cord, where blocking the vessel is generally well tolerated.

When should I see a doctor?

Get emergency medical help straight away if you have sudden, severe back pain, especially if it comes with a severe headache, weakness or numbness in your arms or legs, or new problems controlling your bladder or bowel. These can be signs of bleeding around the spinal cord, which needs urgent assessment and treatment to give you the best chance of recovery.