Rheumatoid Arthritis

Rheumatoid Arthritis

·        Persistent, symmetrical, deforming, peripheral arthropathy

·        Epidemiology:

o   Peak onset: 4^th decade

o   Prevalence: 1-3%

o   Female:male = 3:1

·        Pathogenesis:

o   Microbial agent initiates the disease: current suspect is EBV, plus others 

o   Presentation of (unknown) antigen to CD4+ T-helper cells + plasma cells and macrophages ® cytokine-mediated synovial neutrophilic exudate + ­vascularity ® cartilage-degrading enzymes + fibrosis + panus formation (inflamed synovium) + ­osteoclastic activity + ligament and tendon damage 

o   ® Painful, unstable, disrupted joint (eg subluxed, deformed, etc) 

o   65 – 80% are HLA DR4 or DR1 +ive, plus further specific DR alleles (eg Q(k/R)RA motif in the DRB1-HV3 region of the T-cell antigen receptor)

o   Autoimmunity to type 2 collagen can be demonstrated in most patients with RA

o   80% have Rheumatoid Factors: autoantibodies (mainly IgM) to the Fc portion of autologous IgG 

o   Implicated mediators are cytokines: TNF, IL-1, IL-6, IL-15, interferon-a, growth factors, proteases, elastases 

·        Presentation: 

o   Common: Swollen, painful, stiff hands and feet, especially in the morning. Progresses to larger joints

o   Less common:

§  Palindromic: relapsing and remitting monoarthritis of different large joints

§  Persistent monoarthritis (especially the knee)

§  Systemic illness: ¯weight, pericarditis, pleurisy

§  Vague limb girdle aches

§  Sudden-onset widespread arthritis

o   Greatest damage occurs in first 4 – 5 years

·        Pattern of involvement:

o   Usually symmetrical

o   Most RA involves:

§  PIP and MCP joints and wrists (DIP spared) in the hands

§  Tarsal and MTP joints in the foot

o   Also involves:

§  Elbows

§  Shoulders (eg Pencilling – erosion of distal end of the clavicle)

§  Small joints of upper cervical spine: Atlanto-Axial instability: anterior subluxation of C1 on C2 with cervical flexion due to erosion of the transverse atlantal ligament ® threatens spinal cord 

§  Lumbo-sacral region usually spared

§  Hips

§  Knees

·        Deformities:

o  Initially sausage-shaped fingers and MCP joint swelling

o  Ulnar deviation and volar subluxation (partial dislocation) of the fingers

o  Fingers: Swan Neck and boutonniere (buttonhole) 

o  Z deformity of the thumb: hyperextension of the IP joint and fixed flexion and subluxation of the MCP joint

o  Subluxation of the wrist, with prominent radial head

·        Extra-articular involvement: 

o  Nodules: subcutaneous central zone of fibrinoid necrosis surrounded by pallisading histiocytes and fibroblasts. May occur in viscera, including heart, lung and GI

o  Anaemia

o  Lymphadenopathy

o  Vasculitis

o  Carpel Tunnel Syndrome (early manifestation) 

o  Multifocal neuropathies (= Mononeuritis Multiplex): Sequential, multifocal, random involvement of non-contiguous peripheral nerve trunks (there are other causes besides RA)

o  Splenomegaly

o  Eyes: episcleritis, scleritis, keratoconjunctivitis sicca

o  Pericarditis

o  Pulmonary fibrosis

o  Amyloidosis

o  Not glomerulonephritis

·        Investigations

o  X-ray

o  Bloods: Rheumatoid factor +ive in 75%

·        Treatment:

o  Regular exercise

o  Physiotherapy

o  Occupational therapy

o  Household and personal aids (eg wrist splints)

o  Intralesional steroids

o  Surgery

o  Drugs:

§  NSAIDs (eg ibuprofen): Least likely to cause a bleed. Contraindicated if asthma or peptic ulcer. To control inflammation/pain

§  Steroids: To control flare-ups. Can reduce erosions if given in early disease. Need to keep dose low (ie 7.5 mg/day) – but due to symptomatic improvement patients often want more. SE: ¯bony density, cataract, fluid retention, peptic ulcers

§  Disease modifying drugs:See Disease Modifying Anti-Rheumatic Drugs (DMARDs) Topic, . All have side effects, monitoring essential. All can cause rash