Non-radiographic axial spondyloarthritis: symptoms, diagnosis and treatment

Axial spondyloarthritis is an umbrella term for inflammatory arthritis that mainly affects the spine and the sacroiliac joints, where the spine meets the pelvis. The NHS describes ankylosing spondylitis (AS) as a long-term condition in which the spine and other areas of the body become inflamed, and as a type of axial spondyloarthritis.

In AS, changes to the spine or sacroiliac joints can be seen on an X-ray. The NHS describes a similar condition, non-radiographic axial spondyloarthritis, where those changes cannot be seen on an X-ray but can sometimes be seen on an MRI scan. The name simply means "not visible on a standard X-ray". It does not mean the pain or inflammation is milder or less real.

The NHS notes that the symptoms and treatment are similar for the two conditions, which is why its page about ankylosing spondylitis is also the main NHS source for this condition.

The NHS says the symptoms of AS usually develop slowly over several months or years, may come and go, and not everyone has all of the main symptoms. Because the NHS says non-radiographic axial spondyloarthritis has similar symptoms, the same list applies.

• Back pain and stiffness that gets better with exercise but does not improve, or gets worse, with rest.

• Pain and stiffness that are worse in the morning and at night, sometimes waking you during the night.

• Pain in the area around the buttocks.

• Pain, swelling and warmth in other joints such as the hips and knees.

• Enthesitis, which is painful inflammation where a tendon or ligament joins a bone, for example behind the heel, under the heel or where the ribs join the breastbone.

• Chest pain and difficulty expanding the chest when breathing deeply, if the ribs are affected.

• Fatigue, which the NHS describes as a common symptom.

The NHS says it is common for people with AS to also have other conditions, including iritis (also called acute anterior uveitis, where the front part of the eye becomes red and swollen), psoriasis and inflammatory bowel disease. A painful, red eye should therefore not be ignored if you already have an axial spondyloarthritis diagnosis.

The NHS says AS can be difficult to diagnose because the condition develops slowly and there is no definitive test. The first step is to see your GP, who will ask about your symptoms, when they started and how long you have had them. Back pain associated with the condition can be quite distinctive, as it usually does not improve with rest and may wake you at night.

Blood tests may be arranged to look for signs of inflammation. If results suggest inflammation you will be referred to a rheumatologist, a specialist in conditions affecting muscles and joints. The NHS adds that normal results do not rule out the condition, and more tests might be needed.

A rheumatologist will usually arrange imaging of the spine and pelvis, which may include an X-ray, an MRI scan or an ultrasound scan, and sometimes a genetic blood test for the HLA-B27 gene variant. The NHS says this test can contribute to a diagnosis but is not entirely reliable, since not everyone with the condition has it and some people carry it without ever developing the condition.

The NHS explains the distinction as follows: if an X-ray cannot confirm AS you will usually be offered an MRI scan. If the MRI shows inflammation of the sacroiliac joints you will be diagnosed with non-radiographic axial spondyloarthritis. Sometimes inflammation does not show on either scan, and you might still be diagnosed with non-radiographic axial spondyloarthritis if you have the HLA-B27 gene variant and the symptoms of the condition.

The NHS says it is not known what causes ankylosing spondylitis, although there is thought to be a link with a gene variant called HLA-B27. It describes this variant as found in most people with AS. Having the gene does not mean someone will develop the condition.

The NHS says there is no cure and the damage cannot be reversed, but treatment can relieve symptoms and help delay or prevent the spine joining up (fusing) and stiffening. It confirms these treatments also help in non-radiographic axial spondyloarthritis. In most cases treatment combines exercise, physiotherapy and medicine.

The NHS says the outlook for AS is highly variable. For some people the condition improves after an initial period of inflammation, whereas for others it gets progressively worse. Some people remain fully independent or minimally disabled in the long term, while others eventually become severely disabled as bones in the spine fuse and other joints are damaged.

It also says that with modern treatments AS does not normally affect life expectancy significantly, although it is associated with a higher risk of osteoporosis, spinal fractures and cardiovascular disease. Your rheumatology team will monitor how you are doing over time.

The National Axial Spondyloarthritis Society (NASS) is the UK charity the NHS points to for information on living with the condition, including working, travelling and driving.

Most care in the UK is delivered through NHS rheumatology services. Some people use private rheumatology consultations or physiotherapy for quicker access to assessment or MRI, but long-term biologic medicines are normally prescribed within NHS rheumatology under national guidance.

See your GP if you have persistent back pain with the features described above, particularly if it began in your teens or twenties. The NHS back pain advice says to call 999 or go to A&E if back pain comes with pain, tingling, weakness or numbness in both legs, loss of feeling around the genitals or anus, or changes in bladder or bowel control. It says to ask for an urgent GP appointment or call 111 if back pain comes with feeling hot, cold, shivery or unwell, or if it is severe, sudden or getting worse quickly.