Axial Spondyloarthritis

Axial Spondyloarthritis - What is in another new name? Those familiar with ankylosing spondylitis (AS) may wonder why axial spondyloarthritis (Axial SpA) an even bigger mouthful - has now entered the frame. It is a horrible term but it does actually reflect an important advance in understanding. Moreover it allows that crucial development - early diagnosis.

A huge problem with AS, from the professionals’ viewpoint, is that diagnosis is too often long delayed. One factor underpinning this is the requirement, by convention, for abnormalities on X-rays of the sacroiliac joints before the diagnosis of AS can be made. Thus, even though effective treatments are now available for many patients they are often used late in the day. In 1984, when the modified New York criteria for classifying AS were published, they were an important step forward. These required a combination of suggestive symptoms and/or signs with definitely abnormal sacroiliac joint X-rays but we now recognize that symptoms are variable, signs may be undetectable and radiographic changes on X-rays may take years to develop – or may never do so. Indeed, in women in particular, such changes may be mild or absent so that many have had to struggle on undiagnosed even longer than men.

It is now the norm in many parts of the World to assess painful spinal conditions using magnetic resonance imaging (MRI) and it is clear that diagnostic inflammatory changes can be seen on spinal and sacroiliac MRI scans in people whose X-rays are normal. So far as we know, so long as the usual differential diagnoses of AS have been excluded, those with typical (radiographic) AS and those with symptoms but imaging changes only detectable on MRI have the same condition. It is now recognized, therefore, that there is a spectrum of inflammatory spinal disease; at one end is typical AS with all its fearful and irreversible bony (and lifestyle) changes while at the other is a condition with spinal inflammation only detectable by the right MRI scanning protocols combined with a high index of suspicion. This spectrum is referred to as axial SpA; AS is therefore included within it but many more people have axial SpA than have AS. Some of them, with normal X-rays (non-radiographic axial SpA) will progress to AS but some will not. If treatments can be shown to prevent the irreversible bony changes of AS then the ideal time to use them would be during the non-radiographic stage. Moreover, for people with troublesome symptoms of axial SpA the ideal time to get a diagnosis is as early as possible. With MRI scanning diagnosis of axial SpA is now, possible much earlier than when we relied on X-ray changes.

However, a new name doesn’t solve problems by itself – it is just a tool. Recognising the breadth of the spectrum of axial SpA and the availability of sensitive spinal imaging certainly offer the promise of early diagnosis but the reality has yet to blossom. We still overlook the diagnosis far too often amidst the masses of people with back pain so that clinicians have to sharpen up if we are to see this awful term serve a truly useful purpose.