Ankylosing Spondylitis

Spondylarthritides are group of diseases characterized by involvement of spine as well as joints. Ankylosing spondylitis is a prototype of these diseases. Other causes of spondylarthritides in adults and children include psoriasis, inflammatory bowel diseases and genitourinary or bowel infection. Rigidity of spine is common sequelae of these diseases. Around 0.25% population in India is estimated to be affected by these diseases
Ankylosing-SpondylitisEarly diagnosis is the key to successful management. An Indian study demonstrated diagnostic delay of almost 7 years in cases of ankylosing spondylitis.
Causes: Ankylosing spondylitis is an autoimmune disease. Although the exact cause is unknown, it is more frequent in young males under the age of 40 years. Females can also be affected although their disease appears to be milder. The disease is more frequent in genetically susceptible individuals who are HLA-B27 positive. Relatives of a given patient have 20-40 fold risk of developing ankylosing spondylitis.
Features: Inflammation at sacroiliac joints and entheses are important features of ankylosing spondylitis. The lower end of our spine articulates with pelvic bones at sacroiliac joints. Entheses are sites of attachment of ligaments, tendons or joint-capsule to a bone. Common sites of pain due to enthesitis are spine, upper end of thigh, knee cap, heel and foot. Spinal involvement is characterized by inflammatory back pain. This implies back pain or low back pain of insidious onset occurring at night awakening from sleep, alternating buttock pain and stiffness in the morning lasting for more than 30 minutes. The pain reduces with exercise or anti-inflammatory pain killers. Stiffness of back leads to difficulty in various day-to-day activities such as getting up without support, climbing stairs, prolonged standing, forward bending, looking over shoulders and doing physically demanding activities.
Joints of lower limbs swell in asymmetric fashion. Axial joints (those near center of body) such as hip and those of rib cage are usually involved. Swelling of entire toe (dactylitis) or that of whole or part of foot is another feature.
Ankylosing spondylitis is a systemic (generalized) disease. Involvement of eyes (pain, redness), damage to heart valve (endocarditis), fatigue, derangement of functions of kidneys and lungs can also occur. Involvement of blood vessels in longstanding disease leads to premature deaths in about half of the cases. Progressive disease of entire spine causes a curved, stiff and immovable back which can fracture easily on minor trauma.
Investigations: A good clinical examination is sufficient for diagnosis in most cases. X-rays of sacroiliac joints and spine provide useful information and are usually adequate for diagnosis. MRI is required in selected cases only. Isotope bone scan does not give proper information about inflammation of sacroiliac joint. Ultrasonography can be used to demonstrate enthesitis. Blood examination for ESR and CRP indicate ongoing inflammation. HLA-B27, a commonly misused test, is positive in 8-10% of normal population. 83-94% Indian patients of ankylosing spondylitis are HLA-B27 positive. HLA-B27 positive patients are more likely to have spine, eye and heart disease. HLA-B27 is a costly test and must be used in selected patients with less classical clinical features.
All patients of must be regularly assessed for physical function, disease activity and spinal mobility. Bath Ankylosing Spondylitis Functional Index (BASFI), Disease Activity Index (BASDAI) and Meteorology Index (BASMI) are respectively used for these purposes.
This helps in assessing severity of disease and monitoring efficacy of treatment. Therapy can be changed in cases of inadequate response. Outcome will never be known if disease is not assessed on a regular basis.
Treatment: All patients of ankylosing spondylitis must try to learn more about their disease so that they can realize disease progression and complications at an early stage. Regular exercise is an essential part of therapy and should not be missed throughout life. Swimming, cycling and Yoga are good exercises for these patients. Self-help groups and patient associations can be of great help.
Nonsteroidal anti-inflammatory pain killers are mainstay of therapy as they modify the disease process. They must be used continuously under medical supervision. Deficiency of calcium and Vitamin D must be corrected. Sulfasalazine can be used in patients with peripheral arthritis. Resistant cases with high disease activity can respond dramatically to biologic drugs such as infliximab and etanercept. These drugs are expensive and must be used under supervision of a rheumatologist. Insurance companies can sometimes bear the cost of such high cost therapy. Recent reports indicate that bisphosphonates, relatively cheaper drugs, may be effective in treatment of ankylosing spondylitis.
Localized inflammation requires local steroid injections. Patients with intractable hip pain and disability should consider surgery for joint replacement at an early date.

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