03/05/2013 12:11 BST | Updated 03/07/2013 06:12 BST

Invisible Pain...

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I've been on crutches for the last 10 days, owing to sudden and so far unexplained swelling and pain in my ankle and foot. On Sunday, partly because I had a mild case of cabin fever and partly because I felt my poor husband deserved a bit of support (!) I went to Tesco. Kindly driven and greatly assisted by my long-suffering husband.

Now, I've been to Tesco many times. And on many occasions I've been there when in pain. (I've struggled with lower back pain and stiffness since my early 20s). I'm a working mum, I have a full-time, demanding job, and to be honest, I really do like food shopping (but don't tell my husband). But, armed with my crutches on this occasion, I couldn't help but notice the looks of sympathy I received and how people looked as though they would have been more than happy to help me, if needed.

It got me to thinking about invisible pain again and the challenges faced by many who struggle on with a long-term condition that is invisible to most around them.

It's World Ankylosing Spondylitis (AS) Day on Saturday 4 May. Whilst advanced AS can cause fusion in the neck, spine and sometimes other areas and hence a change in posture, it can often be invisible. Not many people know much about AS, despite the fact that it is not a rare condition. It also is a form of arthritis that affects young people. This lack of understanding by the general public can make it incredibly challenging for anyone with the condition to feel understood. This is further complicated by the fact that often a person with AS will have good and bad days. When it's good, they might try to bring some normality back into their life. When it's bad they might feel overwhelmed by their pain, fatigue and inability to do the things they had planned. These good and bad days are often difficult for the outsider to understand, leaving the sufferer to feel on occasion like a fraud. Some people get no respite from their pain and fatigue. All of this can have a significant impact on the sufferer's well-being. The psychological impact of AS is probably as significant as the burden of pain and fatigue.

And let me tell you this other shocking fact. The current delay in the diagnosis of ankylosing spondylitis is between 8 and 11 years! I will leave you to imagine what unnecessary suffering and possible permanent damage that a person might endure during this delay...

So, if you've got time, read on and find out a bit more about this difficult to pronounce condition (go on ... for World AS Day). And, I guess something we should all bear in mind is that often what's presented on the surface might not represent the true picture. A person in pain is not always easy to spot. Next time a young person on the Tube fails to give up his/her seat for an elderly person I hope I might not be so quick to judge...

1. Ankylosing spondylitis is pronounced an-ki-low-sing spon-de-lie-tis and is called AS for short.

2. AS is a painful, progressive form of inflammatory arthritis. It mainly affects the spine but can also affect other joints, tendons and ligaments.

3. Ankylosing means fusing together. Spondylitis means inflammation of the vertebrae. Both words come from the Greek language. Ankylosing spondylitis describes the condition where some or all of the joints and bones of the spine fuse together. Other areas such as the eyes, bowel, lungs and heart can also sometimes be involved with AS.

4. AS affects an estimated 200,000 in the UK -- that's twice the number who have Parkinson's Disease or multiple sclerosis.

5. Research is still ongoing into the genetics of AS but researchers believe that up to 20 different genes must be involved.

6. Symptoms usually begin in early adult life, with the average age of diagnosis being 24.

7. There is currently no cure for AS. It is managed by a combination of pain relief and stretching exercises.

8. AS, especially in its early stages, can be an invisible condition. People with AS are often battling on a daily basis against pain, stiffness and fatigue. This can lead to feelings of isolation, particularly just after diagnosis.

9. As well as the inevitable pain of the disease, AS often generates feelings of frustration and fear. To help them adjust to their diagnosis it is important that they have the support and encouragement of family, friends and work colleagues.

10. Some common problems for people with include: pain and stiffness in the mornings make it hard to get going; sitting in one place can lead to pain and stiffness and not having the same amount of energy or stamina and getting fatigued easily.