04-01-2013, 02:47 PM
Rheumatoid arthritis (RA)
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Introduction
Rheumatoid arthritis (RA) is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks flexible joints.
The process involves an inflammatory response of the capsule around the joints secondary to swelling of synovial cells, excess synovial fluid, and the development of fibrous tissue in the synovium.
The pathology of the disease process often leads to the destruction of articular cartilage and ankylosis of the joints. Rheumatoid arthritis can also produce diffuse inflammation in the lungs, membrane around the heart (pericardium), the membranes of the lung (pleura), and white of the eye (sclera), and also nodular lesions, most common in subcutaneous tissue.
Although the cause of rheumatoid arthritis is unknown, autoimmunity plays a pivotal role in both its chronicity and progression, and RA is considered a systemic autoimmune disease.
o About 1% of the world's population is afflicted by rheumatoid arthritis, women three times more often than men.
o Onset is most frequent between the ages of 40 and 50, but people of any age can be affected.
o In addition, individuals with the HLA-DR1 or HLA-DR4 serotypes have an increased risk for developing the disorder.
o It can be a disabling and painful condition, which can lead to substantial loss of functioning and mobility if not adequately treated.
o It is a clinical diagnosis made on the basis of symptoms, physical exam, radiographs (X-rays) and labs, although the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) publish classification criteria for the purpose of research.
o Diagnosis and long-term management are typically performed by a rheumatologist, an expert in joint, muscle and bone diseases.
Signs and symptoms
While rheumatoid arthritis primarily affects joints, problems involving other organs of the body are known to occur.
Extra-articular ("outside the joints") manifestations other than anemia (which is very common) are clinically evident in about 15–25% of individuals with rheumatoid arthritis.
It can be difficult to determine whether disease manifestations are directly caused by the rheumatoid process itself, or from side effects of the medications commonly used to treat it – for example, lung fibrosis from osteoporosis from corticosteroids.
JOINTS
• The arthritis of joints known as synovitis is inflammation of the synovial membrane that lines joints and tendon sheaths. Joints become swollen, tender and warm, and stiffness limits their movement. With time RA nearly always affects multiple joints (it is a polyarthritis), most commonly small joints of the hands, feet, and cervical spine, but larger joints like the shoulder and knee can also be involved. Synovitis can lead to tethering of tissue with loss of movement and erosion of the joint surface causing deformity and loss of function.
• In arthritis of non-inflammatory causes, signs of inflammation and early morning stiffness are less prominent with stiffness typically less than 1 hour, and movements induce pain caused by mechanical arthritis. In RA, the joints are often affected in a fairly symmetrical fashion, although this is not specific, and the initial presentation may be asymmetrical.
• As the pathology progresses the inflammatory activity leads to tendon tethering and erosion and destruction of the joint surface, which impairs range of movement and leads to deformity. Medical students are taught to learn names for specific deformities, such as ulnar deviation, boutonniere deformity, swan neck deformity and "Z-thumb," but these are of no more significance to diagnosis or disability than other variants, since they occur in osteoarthritis as well. "Z-thumb" or "Z-deformity" consists of hyperextension of the interphalangeal joint, fixed flexion and subluxation of the metacarpophalangeal joint and gives a "Z" appearance to the thumb.
HEART AND BLOOD VESSELS
o People with rheumatoid arthritis are more prone to atherosclerosis, and risk of myocardial infarction (heart attack) and stroke is markedly increased.
o Other possible complications that may arise include: pericarditis, endocarditis, left ventricular failure, valvulitis and fibrosis.
o Many people with rheumatoid arthritis do not experience the same chest pain that others feel when they have angina or myocardial infarction.
o To reduce cardiovascular risk, it is crucial to maintain optimal control of the inflammation caused by rheumatoid arthritis, and to use exercise and medications appropriately to reduce other cardiovascular risk factors such as blood lipids and blood pressure.
o Doctors who treat rheumatoid arthritis patients should be sensitive to cardiovascular risk when prescribing anti-inflammatory medications, and may want to consider prescribing routine use of low doses of aspirin if the gastrointestinal effects are tolerable.
Diagnosis
Imaging
X-rays of the hands and feet are generally performed in people with a polyarthritis. In rheumatoid arthritis, there may be no changes in the early stages of the disease, or the x-ray may demonstrate juxta-articular osteopenia, soft tissue swelling and loss of joint space. As the disease advances, there may be bony erosions and subluxation. X-rays of other joints may be taken if symptoms of pain or swelling occur in those joints.
Blood test
When RA is clinically suspected, immunological studies are required, such as testing for the presence of rheumatoid factor. A negative RF does not rule out RA; rather, the arthritis is called seronegative. This is the case in about 15% of patients. During the first year of illness, rheumatoid factor is more likely to be negative with some individuals converting to seropositive status over time. RF is also seen in other illnesses, for example Sjögren's syndrome, Hepatitis C, chronic infections and in approximately 10% of the healthy population, therefore the test is not very specific.
Criteria
joint involvement, designating the metacarpophalangeal joints, proximal interphalangeal joints, the interphalangeal joint of the thumb, second through fifth metatarsophalangeal joint and wrist as small joints, and shoulders, elbows, hip joints, knees, and ankles as large joints.
Monitering progression
The progression of rheumatoid arthritis can be followed using scores such as Disease Activity Score of 28 joints (DAS28). It is widely used as an indicator of RA disease activity and response to treatment, but is not always a reliable indicator of treatment effect.