8 Things you didn’t know about Ankylosing Spondylitis

8 Things you didn’t know about Ankylosing Spondylitis

1. Ankylosing Spondylitis (AS) was first described by an Irish man

Kerry physician, Bernard Connor first described the condition in 1693 in a skeleton  from a church graveyard. If you look carefully at the above illustration from that skeleton you can see how the spine is fused.

2. It takes an average of 8 years to diagnose it.

Many patients will attend a large number of doctors, physical therapists and other healthcare professionals before getting a diagnosis (for reasons why, see below).

3. Blood tests can be normal

The blood tests which are traditionally used in the diagnosis of other forms of inflammatory arthritis, the ESR and CRP tests, are normal in up to 50% of patients.

The HLA B-27 genetic test can be positive in up to 90% of patients. Sound good? Unfortunately 8% of healthy adults (without AS) have a positive test as well. This means if you test 100 people with low back pain unrelated to AS, at least 8 of them would have a positive test. The test needs to be used carefully and interpreted in the light of other features of the disease.

4. MRI scans can miss it too.


Left Sided Sacroillitis on MRI

Although MRI is probably the most reliable test for making a diagnosis, its important to scan the correct body part. An MRI of the sacroiliac joints (the joints where the spine jomeets the pelvis) is abnormal in 70% of patients with established AS. MRI of the rest of the spine scan can show signs of AS in the 25-30% of patients with AS who have normal MRI’s of their sacroiliac joints. The sensitivity of the test is  improved where the scans are looked at by a radiologist who has an interest in arthritis related conditions.

 5. Can cause chest pain

In addition to causing inflammation of the spine itself, AS can cause inflammation of lots of other structures e.g. the ribs and their attachments (aka ‘costochondritis’)

6. Can cause sore heels

In addition to causing spinal inflammation, AS causes ‘enthesitis’. Enthesitis is a form of inflammation of where ligaments and tendons attach to bone. It can cause inflammation at the attachment of the plantar fascia (a ligament in the sole of the foot) – plantar fasciitis. It can also cause inflammation of the achilles tendon  – Achilles tendonitis.

7. Can cause sore eyes

AS can be associated with an acute inflammation of the eye (uveitis) in up to 25% of patients. This will typically cause an eye that is red AND painful and needs to be treated urgently. If you have AS and an acutely painful red eye, you should be assessed by an ophthalmologist.

 8. It is very treatable

For some patients with years of chronic low back pain it can be a relief to get a diagnosis of a condition like AS which is very treatable. Until about 10 years ago, the treatment of AS revolved around anti-inflammatory medications and physiotherapy (this still sufficient for some patients). In the last few years the development of biologic therapies (Enbrel, Humira, Remicade, Simponi) has resulted in dramatic relief from the symptoms of Ankylosing spondylitis for many patients. There are subtle differences between the drugs (not every drug works for every patient) but as whole they tend to be very effective.

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