Ankylosing spondylitis

Almost everyone gets back pain, and it usually behaves predictably: it turns up after physical effort and settles once you lie down. Ankylosing spondylitis works the other way round. It is a chronic inflammation of the joints of the spine and pelvis that starts in young adulthood, grows worse at rest and eases with movement. Doctors group it with the axial spondyloarthritis conditions. The disease cannot be cured, but its course can now be changed considerably, provided somebody recognises it instead of writing off years of symptoms as a weak back.

How this pain differs from ordinary backache

What alerts a doctor is not the intensity of the pain but its pattern. Inflammatory back pain gives itself away through a combination of features that rarely occur together in muscle strain or a slipped disc:

• the first complaints appear before the age of forty, most often between twenty and thirty;
• the pain builds up gradually over months, rather than after one awkward movement;
• in the morning the body feels stiff and locked, and it takes half an hour or more to loosen up;
• the pain wakes you in the second half of the night and forces you to get up and walk about;
• walking and exercise make it better, lying on the sofa makes it worse;
• it sits deep in the buttock, sometimes alternating between the right and left side;
• an ordinary anti-inflammatory tablet relieves it quickly and almost completely.

Three or four of these features, in pain that has lasted longer than three months, are reason enough to look for inflammation rather than settle for a scan reported as wear and tear.

What else becomes inflamed besides the spine

The disease rarely stays in the spine. The places most often affected are those where a tendon or ligament attaches to bone, which is called enthesitis. Hence the stubborn pain behind and under the heel, below the knee, and where the ribs meet the breastbone. When the rib joints are inflamed, the chest hurts on a deep breath and the breath itself becomes shallower, which is frightening and often sends people to a cardiologist first. Other features include:

• arthritis of the large joints of the legs, especially hips, knees and ankles, usually without symmetry;
• dactylitis, in which a whole finger or toe swells and looks like a sausage;
• acute inflammation of the front of the eye, known as uveitis;
• psoriasis of the skin and nails;
• inflammatory bowel disease, with prolonged loose stools containing mucus or blood, abdominal pain and weight loss;
• exhausting fatigue, which has several sources at once: the inflammation itself, broken sleep from night pain, and anaemia.

Situations that cannot wait until Monday

Symptoms generally develop over years, but the disease has a few turns that call for help the same day.

• A red, painful eye with light sensitivity, watering and blurred vision, usually on one side. This is uveitis, and an eye specialist should look at it today rather than next week: prolonged inflammation leaves adhesions and raises the pressure inside the eye.
• New back or neck pain after a fall from standing height in someone with long-standing disease. A fused spine loses its spring and breaks under loads that would do nothing to a healthy person. Such a fracture is easy to miss on a plain film, so tell the doctor about your diagnosis directly.
• Weakness or numbness in the legs, loss of sensation around the genitals and anus, or difficulty passing or holding urine and stool. These point to compression of the nerves at the base of the spine. Call the emergency number 112.
• A high fever with shivering while on treatment that suppresses the immune system: infection develops faster than usual in these patients.

Why the disease starts at all

No single cause has been found. The great majority of patients carry a particular tissue-type gene variant called HLA-B27. It is tempting to treat this as a verdict, but there are dozens of times more carriers than there are patients, and almost all of them are healthy. The gene only makes the immune system more vulnerable; something else sets the process off, and the composition of the gut bacteria is one of the leading suspects.

The condition does run in families, and relatives of a patient are affected more often than average, although the risk for any individual child stays low. What is definitely not on the list of causes is injury, cold draughts, heavy manual work or salt deposits. The one habit with proven influence is smoking: in smokers the spine fuses faster and treatment works less well.

How the diagnosis is confirmed

There is no single test that settles the question, and that is the main difficulty. The doctor asks in detail about the character of the pain and checks how far the spine moves in different directions and how much the chest expands on breathing in. Investigations follow.

• Blood tests for inflammation, the ESR and C-reactive protein. In roughly a third of patients these are normal, and a normal result does not rule the diagnosis out.
• An X-ray of the pelvis. It shows changes in the sacroiliac joints, but those changes build up over years, so in a young person the film is often clean.
• MRI of the same joints. It detects swelling within the bone, that is, inflammation at a stage when the bone itself is still intact.
• The HLA-B27 test, which is supportive only: it strengthens a suspicion but proves nothing on its own.

If the X-ray is clear while MRI shows inflammation, the diagnosis is worded differently, as non-radiographic axial spondyloarthritis. It is the same disease at an earlier stage and is treated in the same way. Years often pass between the first complaint and the diagnosis, largely because a young person with night-time back pain is managed for a long time as a case of ordinary degenerative disc disease.

Treatment, with movement first

Exercise here is not an add-on to medication but an equal part of the treatment, and it only works if it is daily. What is needed are extension and stretching exercises for the back and breathing exercises that open the chest; swimming is useful. It is best to build the programme with a physiotherapist and then do it yourself, ten or fifteen minutes at a time, but every single day. The second most important decision is to stop smoking.

The backbone of drug treatment is the non-steroidal anti-inflammatory group: these relieve pain and morning stiffness, and taken continuously they appear to slow down fusion. They are used with an eye on the stomach, kidneys and blood pressure, and they are unsuitable in the second half of pregnancy. If the joints of the arms and legs are inflamed, a disease-modifying drug is added, though it has no effect on the spine. A steroid injection is given into a specific inflamed joint; steroid tablets are of no use for spinal disease.

When this is not enough, treatment moves on to biological agents that block tumour necrosis factor or interleukin-17, or to janus kinase inhibitors taken as tablets. They suppress inflammation powerfully, so latent tuberculosis and viral hepatitis are ruled out before starting. Surgery is rarely needed, and when it is, it is most often replacement of a destroyed hip joint. No treatment can restore movement to vertebrae that have already fused, which is precisely why starting early matters.

What happens over the years

The course varies enormously. In some people everything quietens down after a few active years and barely interferes with life; in others the spine slowly loses its range, posture becomes fixed and the chest no longer expands fully. A particular feature is early osteoporosis: on the outside the vertebrae grow bony bridges while inside the bone weakens, which explains fractures after minor trauma.

The risk of heart and vascular disease is above average with chronic inflammation, so blood pressure, weight and cholesterol deserve serious attention rather than a passing mention. Less common are rhythm disturbances, changes to the aortic valve, scarring at the top of the lungs and kidney damage. Most patients nevertheless keep working and stay independent, and life expectancy is close to average.

Online consultation: how it helps

A remote appointment is valuable at the early stage, when the back has been aching at night for months and no explanation has emerged. The doctor can work out whether the pain looks inflammatory, review the scans and blood tests already done, and advise what to investigate and which specialist to see. With an established diagnosis, online visits are convenient for day-to-day questions: how to rebuild the exercise routine, what to do during a flare, how to prepare for travel or an operation. Acute situations are not handled this way: a red eye, a fresh back injury or weakness in the legs needs an in-person examination, not a message thread.

This material is for information only and does not replace medical advice.