Back pain & stiffness? Ankylosing Spondylitis is the kind of arthritis that strikes when you're young

Dr Uma Kumar

The word Ankylosing Spondylitis (AS) is derived from the Greek words ankylos meaning ‘stiffening’, spondylos meaning ‘vertebra and -itis meaning ‘inflammation’.

AS is a chronic inflammatory type of spondyloarthritis (a broad term for all types of arthritis that affects the spine) that is further classified as an ‘axial spondyloarthritis’ because it affects the joints of the spine and pelvis (where the sacral bone attaches to the iliac bone on either side of the body).


When spinal ligaments get inflamed at the point where they attach to the vertebrae, the ‘bonemaking cells’ of the body get stimulated and start to grow bone within the ligaments, which results in the formation of bony bridges between adjoining vertebrae — this is what leads to a stiff back.

Sometimes, other joints of the body such as the ankle, knee and hip may also be affected. AS is more common in young men between 20 and 30 years of age than in women. It can occur in children as well. The prevalence of AS ranges from 0.8% to 1.8% in the general population.

POSSIBLE CAUSES
There are genetic and environmental factors linked to AS. The exact cause of AS is unknown. However, there is a strong genetic predisposition and most patients with AS have the HLA B27 gene. About 6-8% of the Indian population has the HLA B27 gene and among them, those with a family history of AS in a first-degree relative have a 30% chance of developing the disease.

However, only 2% of individuals with this gene actually develop the disease. It is hypothesised that some stimuli (for example, environmental factors and gut microbiome) trigger AS development in genetically predisposed individuals. Moreover, AS can also develop in individuals without HLA B27. It is likely that there are some undiscovered genetic factors that could also be involved in its etiology.

SYMPTOMS
Initial symptoms may not appear alarming, but they can be serious. Patients with AS initially develop symptoms such as low back pain and stiffness that lasts for more than 30 minutes and worsens in the morning or after prolonged inactivity. They often find it difficult to turn on the bed during the later part of the night and the pain sometimes wakes them up from sleep. Typically, the back pain improves with activity. Some of the tendons and ligaments of the body may also get inflamed (for example, costochondritis and Achilles tendinitis).

Other symptoms of AS are chest stiffness and pain in the neck, hip, shoulder, glutes (buttocks) and heel, as well as arthritis of the knee, ankle, toes or fingers. About 30% of patients may develop uveitis (painful red eye) and a similar number of patients with longstanding disease may develop osteoporosis (thin weak bones). The lungs, heart (valves) and kidneys may also get affected.

DIAGNOSIS
AS is diagnosed based on a patient’s clinical profile and radiological (X-ray) investigations. Blood tests include genetic tests to detect the HLA B27 gene; if the tests show up raised erythrocyte sedimentation rates (ESR) and increased C-reactive protein (CRP) levels, it suggests ongoing inflammation.

X-ray imaging cannot detect bone changes during the initial stages of the disease making early diagnosis difficult. However, MRI scans of the sacroiliac joints can be used to diagnose AS in the early stages, when the X-ray of this region still appears ‘normal’.

TREATMENT
Treatment can help slow down or stop the progression of AS. The aim of treatment is to (1) Relieve pain (2) Slow down or stop disease progression, and (3) Maintain mobility of the spine. Patients prescribed medicines must take them regularly and not ‘as and when required’.

Regular followup with the doctor is extremely important to adjust the dose and detect any drug adverse effects or any complication or comorbidity at the earliest.

Surgery is rarely required for correcting spinal deformity, though a hip or knee replacement surgery may be needed if there is significant joint damage.

Patients with AS must exercise regularly because it helps limit spinal deformity and maintain their spinal movement and flexibility, while also relieving the back pain. Swimming and deep breathing are the best exercises.

In addition, a hot shower in the morning can help ease the pain and stiffness. Patients should avoid smoking, eat a healthy diet and maintain a healthy weight.

AS is not curable but it is completely treatable if detected early. Only 10% of patients have severe disabling disease. With the help of correct medication and lifestyle modification, approximately 80% people with AS remain completely independent or just minimally disabled in the long term.

(The writer is the Head of Department of Rheumatology at the All India Institute of Medical Sciences, New Delhi)