What is ankylosing spondylitis (AS)?

AS is disease in which the main feature is inflammation in the spine, and the associated joint between the spine and the pelvis (the sacro-iliac joint) The hip joint and shoulders are also involved fairly often, but other joints rarely. It’s call “ankylosing” because the inflammation leads to lack of mobility in the spine with formation of new bone and a fusing together of the bones of the spine so that it is held rigidly and restricts movement.

It usually starts in the twenties, though symptoms in teenagers aren’t unusual. Men have worse symptoms than women do, so in women the diagnosis is sometimes not made until they reach an older age. The symptoms – backache, especially first thing in the morning or after prolonged sitting - come on very gradually, and there is often a gap of several years between onset of symptoms and a definite diagnosis. This is partly because backache is so common that it’s easy to overlook the different and continuing symptoms of AS patients in the early stages. Other kinds of backache are less likely to be more severe first thing in the morning, and likely to be made worse by activity whereas activity helps AS patients.

Apart from joints AS patients commonly get inflammation of the eye (iritis) which needs specialist treatment, and can (less commonly) have changes on their chest x-ray or a leaky heart valve. As well as involvement of the spine, pain in various places where ligaments and tendons are attached to bones is common (e.g. Achilles tendon). Many patients complain of severe fatigue apart from their pain, and this is characteristic of chronic inflammation – like having flu all the time.

Diagnosis.

This is mainly made, especially early, by listening carefully to the symptoms that the patient describes and noting the pattern of inflammatory back pain. Early on there may be little abnormal to find on examination, but with time movement of the spine will become limited, and movements of hips or shoulders may be painful or decreased. There may be hints from

ligament and tendon involvement, or eye inflammation.

Tests are not always helpful in early disease, but all patients will eventually develop abnormal x-rays of their sacro-iliac joints. This can take several years, and MRI is now allowing earlier and more accurate diagnosis. Blood tests often show abnormalities of inflammation, but not always.

One blood test is controversial for diagnosis: this is checking for the presence of the HLA-B27 tissue type. About 95% of AS patients have this tissue type, so at first sight this seems a great test. But, about 7% of the normal population are also HLA-B27+. And since most people get backache at some point in their lives there will be many more HLA-B27+ patients with backache who don’t have AS than there are AS patients. However, the test can still be useful if interpreted carefully.

Treatments.

These can be divided into those, which improve symptoms, and those, which delay the loss of mobility. The best way to maintain mobility for as long as possible is to perform a specific set of exercises very regularly. Patients are given advice on exercise by specialist nurses/physiotherapists and then seen regularly for measurement of movement of the spine and other joints. In this way they can see whether or not they are managing to keep mobile, and can be encouraged to maintain or re-start exercise.

For online advice on exercises, look at the National Ankylosing Spondylitis Society website.

At Addenbrooke’s, pool sessions are run for people with AS. Click here for the timetable and contact details. (coming soon)

Most patients need pain relief, mainly using anti-inflammatory drugs (e.g. diclofenac, naproxen etc), and their use can help in maintaining the exercise programme.
Until recently there were few other useful interventions, and poor responses to most of the drug used for rheumatoid arthritis. However, very encouraging results are being obtained using the TNF inhibitor drugs (see drug information section on this website). In acute flares intravenous steroids may be helpful.

What are the risks of my children developing the disease?

AS does run in families, and HLA-B27+ patients who have a relative with AS are far more likely to get the disease than B27+ people with no family history. This tells us that there are other important genes involved – and we are well on our way to finding some of these.

But not everyone with an AS relative will get disease – in fact only about 1 in 8. This is where the B27 blood test is really helpful; a relative of a patient with AS who develops some back pain and is negative for HLA-B27 is at very low risk of getting the disease (especially if the relative is B27+).

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