Written by Jonathan Chan, MD, as told by Haley Levine
Confused about the difference between ankylosing spondylitis, axial spondyloarthritis and non-radial axial spondyloarthritis? With so many similar terms, it can be hard to tell what it is. WebMD reached out to rheumatologist Jonathan Chan for answers to some of the most pressing questions. Here’s what you need to know.
What is nonradiative axial spondyloarthritis?
It’s a type of arthritis known as axial spondyloarthritis that affects the spine and sacroiliac joints. These are the joints that connect the lower spine to the pelvis. It causes pain in the lower back, hips, and buttocks. There are two classes of axSpA: non-radial axonal spondylitis (nr-axSpA) and ankylosing spondylitis (AS). If you have the first, this means that doctors cannot see any damage to your joints on the X-ray. But as soon as they start seeing them, your condition is the same.
It’s more common than many of us realize. Up to 6% of people with chronic back pain will eventually receive a diagnosis of nr-axSpA. The earlier you are diagnosed, the better your prognosis, and the less likely you are to progress to AS.
What causes nr-axSpA?
We don’t know for sure, but family history seems to play a big role. You are more at risk if a first-degree relative, such as a parent or sibling, already has the disease. While there are about 30 genes associated with its development, one in particular – the human leukocyte antigen, HLA-B27 – appears to particularly increase the risk. Age may also play a role, with symptoms usually beginning in your twenties. Smoking is also a risk factor. But unfortunately, I still have a lot of patients who have never smoked, eat well and exercise, and still go on to develop nr-axSpA.
Will nr-axSpA turn into ankylosing spondylitis?
It’s hard to say. It is actually controversial as to whether or not they are even the same disease. We know that some people with nr-axSpA will go on to develop ankylosing spondylitis. A 2018 study found that about 5% of patients do so after 5 years, and nearly 20% do so after 10 years. There appear to be some risk factors for progression, such as having the HLA-B27 gene, or blood tests that show elevated levels of C-reactive protein, a substance that indicates inflammation. But honestly, from a therapeutic perspective, it makes no difference. All the treatments we use for ankylosing spondylitis work on nr-axSpA and vice versa. The key is to get an early diagnosis. It often takes more than 10 years.
What are the symptoms of nr-axSpA and why can they sometimes be missed?
Most of the time, the pain is in the lower back, buttocks, and hips. But it is different from traditional back pain. It does not happen suddenly, but rather it happens slowly, over a period of weeks to months and even years. It gets better with activity, not rest, and may be severe enough to wake you up at night. You may also notice morning stiffness that takes a while to go away. About 40% of the time, patients develop other inflammatory diseases, such as uveitis or inflammatory bowel disease.
The problem is that back pain is a common complaint among patients, and the average primary care physician may not realize that it may be due to inflammatory arthritis. But I would say if you had chronic lower back pain before the age of 45, or you already had an inflammatory disease, you should ask your doctor to refer you to a rheumatologist.
How is nr-axSpA diagnosed?
There are three things your doctor will need to make a diagnosis:
- X-ray of the SI joint
- A blood test to check for the presence of the HLA-B27 gene
- MRI of the area
If the X-ray shows no joint damage, but the MRI shows active inflammation, you most likely have a diagnosis of nr-axSpA. If the X-ray shows damage, you will be diagnosed with ankylosing spondylitis.
How is nr-axSpA handled?
There are three general categories that include:
Physical therapy and exercise. It is best to start as soon as possible after diagnosis. It is very important to do basic exercises to take the pressure off your back, along with cardiovascular and strength exercises. It’s a good idea to see a physical therapist, even if you exercise regularly, to make sure you’re exercising correctly and in a way that doesn’t cause further damage to your joints. Since nr-axSpA can cause the spine to “freeze”, posture training is also important.
Non-steroidal anti-inflammatory drugs (NSAIDs). Prescription medications such as celecoxib (Celebrex) can help control pain and stiffness, but they usually only work in the very early stages. By the time most patients come to see me, they are not enough.
biology. This is a class of drugs that has already revolutionized the treatment of arthritis. They work by blocking proteins that cause inflammation. We usually start with a group of drugs known as TNF factors (anti-TNF agents or TNF inhibitors) such as infliximab, etanercept or adalimumab. But if patients don’t respond to these drugs, or can’t tolerate them, we try another form of biologic medication known as anti-IL-17 therapy, such as secukinumab (Cosentyx) and ixekizumab (Taltz). Thanks to all of these options, many patients with nr-axSpA are able to manage symptoms and halt the progression of the disease.