Rheumatological diseases and investigations

Mr. Arvind Kumar

Introduction 

  1. Rheumatology is a branch of medicine that deals with autoimmune and inflammatory diseases affecting the joints, muscles, bones, and connective tissues. 
  2. These diseases are often systemic and can impact multiple organs, including the heart, lungs, kidneys, and eyes.
  3. Rheumatological diseases can be classified based on their underlying cause, such as autoimmune, degenerative, metabolic, or inflammatory disorders.
  4. Early diagnosis and appropriate treatment are crucial in preventing complications, disability, and decreased quality of life.

 

Types of Rheumatological Diseases

Rheumatological diseases are classified based on their underlying mechanisms and affected tissues. The major categories include:

1. Inflammatory Arthritis

Inflammatory arthritis involves chronic inflammation of the synovium (joint lining) due to an autoimmune or immune-mediated response, leading to pain, swelling, and joint destruction.

Examples:

a. Rheumatoid Arthritis (RA)

  • Pathophysiology: Autoimmune attack on synovial joints due to abnormal activation of immune cells (T-cells, B-cells).
  • Key Features:
    • Symmetrical joint involvement (wrists, fingers, knees).
    • Morning stiffness lasting >1 hour.
    • Rheumatoid nodules, joint deformities in later stages.
    • Extra-articular manifestations: Lung fibrosis, pericarditis, vasculitis.
  • Diagnostic Tests:
    • Rheumatoid Factor (RF) and Anti-Cyclic Citrullinated Peptide (Anti-CCP).
    • X-ray showing joint space narrowing and erosions.

 

b. Psoriatic Arthritis (PsA)

  • Pathophysiology: Autoimmune inflammation linked to psoriasis affecting skin and joints.
  • Key Features:
    • Asymmetrical joint involvement, often affecting fingers and toes (“sausage digits” or dactylitis).
    • Nail changes (pitting, onycholysis).
    • “Pencil-in-cup” deformity on X-ray.

 

c. Ankylosing Spondylitis (AS)

  • Pathophysiology: Chronic inflammation of the spine and sacroiliac joints, leading to progressive spinal fusion.
  • Key Features:
    • Low back pain that improves with exercise.
    • Loss of spinal flexibility (“bamboo spine” on X-ray).
    • Associated with HLA-B27 gene.

 

d. Reactive Arthritis (ReA)

  • Pathophysiology: Immune response triggered by bacterial infections (Chlamydia, Salmonella, Shigella).
  • Key Features:
    • Triad: Arthritis, conjunctivitis, and urethritis (“Can’t see, can’t pee, can’t climb a tree”).
    • Asymmetrical joint inflammation, mostly affecting the lower limbs.

2. Degenerative Joint Diseases (Osteoarthritis – OA)

  • Pathophysiology: Progressive loss of articular cartilage due to mechanical wear and tear, leading to joint space narrowing and osteophyte formation.
  • Key Features:
    • Joint pain worsens with activity and improves with rest.
    • Asymmetrical involvement of weight-bearing joints (knees, hips, spine).
    • Bony enlargements: Heberden’s (DIP) and Bouchard’s (PIP) nodes in fingers.
  • Diagnostic Tests:
    • X-ray: Joint space narrowing, subchondral sclerosis, osteophytes.

3. Connective Tissue Diseases (CTDs)

CTDs are systemic autoimmune disorders that affect skin, blood vessels, and internal organs.

Examples:

a. Systemic Lupus Erythematosus (SLE)

  • Pathophysiology: Autoantibodies (e.g., Anti-dsDNA, Anti-Sm) attack multiple organs.
  • Key Features:
    • Butterfly-shaped malar rash.
    • Arthritis, nephritis, serositis (pleuritis, pericarditis).
    • Photosensitivity, oral ulcers, Raynaud’s phenomenon.
  • Diagnostic Tests:
    • ANA, Anti-dsDNA, Anti-Sm, low complement levels (C3, C4).

 

b. Systemic Sclerosis (Scleroderma)

  • Pathophysiology: Excess collagen deposition leads to skin and organ fibrosis.
  • Key Features:
    • Tight, thickened skin (sclerodactyly).
    • CREST Syndrome:
      • Calcinosis, Raynaud’s phenomenon, Esophageal dysmotility, Sclerodactyly, Telangiectasia.
    • Pulmonary fibrosis, renal crisis.
  • Diagnostic Tests:
    • Anti-Scl-70 (diffuse), Anti-Centromere (limited/CREST).

 

c. Sjogren’s Syndrome

  • Pathophysiology: Autoimmune destruction of exocrine glands (lacrimal, salivary).
  • Key Features:
    • Dry eyes (keratoconjunctivitis sicca) and dry mouth (xerostomia).
    • Increased risk of non-Hodgkin’s lymphoma.
  • Diagnostic Tests:
    • Schirmer’s test, Anti-Ro (SSA) and Anti-La (SSB) antibodies.

4. Vasculitis Disorders

Vasculitis refers to inflammation of blood vessels, leading to tissue ischemia and organ damage.

Examples:

a. Giant Cell Arteritis (Temporal Arteritis – GCA)

  • Pathophysiology: Chronic inflammation of large arteries (esp. temporal artery).
  • Key Features:
    • Severe temporal headache, jaw claudication, sudden vision loss (ophthalmic artery involvement).
  • Diagnostic Tests:
    • Elevated ESR, temporal artery biopsy showing granulomatous inflammation.

 

b. Takayasu Arteritis

  • Pathophysiology: Large vessel vasculitis affecting the aorta and its branches.
  • Key Features:
    • “Pulseless disease” (weak or absent pulses).
    • Unequal blood pressure in arms.
  • Diagnostic Tests:
    • Angiography showing narrowed or occluded aortic branches.

 

c. Granulomatosis with Polyangiitis (GPA, formerly Wegener’s)

  • Pathophysiology: Small vessel vasculitis with necrotizing granulomas.
  • Key Features:
    • Triad: Sinusitis, lung nodules, glomerulonephritis.
  • Diagnostic Tests:
    • C-ANCA (Anti-PR3), lung biopsy.

5. Crystal-Induced Arthritis

a. Gout (Urate Crystal Arthritis)

  • Pathophysiology: Uric acid crystal deposition in joints triggers inflammation.
  • Key Features:
    • Sudden, severe pain in the big toe (Podagra).
    • Red, swollen, tender joints.
  • Diagnostic Tests:
    • Needle-shaped, negatively birefringent crystals in synovial fluid.
    • Elevated serum uric acid levels.

 

b. Pseudogout (Calcium Pyrophosphate Deposition Disease – CPPD)

  • Pathophysiology: Calcium pyrophosphate crystal deposition in joints.
  • Key Features:
    • Similar to gout but affects larger joints (knee, wrist).
  • Diagnostic Tests:
    • Rhomboid-shaped, positively birefringent crystals in synovial fluid.

6. Myopathies (Inflammatory Muscle Diseases)

a. Polymyositis & Dermatomyositis

  • Pathophysiology: Autoimmune attack on muscle fibers.
  • Key Features:
    • Symmetrical proximal muscle weakness.
    • Heliotrope rash (purple eyelid discoloration) in dermatomyositis.
  • Diagnostic Tests:
    • Elevated CK, Anti-Jo-1 antibodies.

Causes and Risk Factors

Causes:

The exact cause of many rheumatological diseases is unknown, but they are believed to be multifactorial, involving genetic, environmental, and immune system dysfunction.

  • Autoimmunity: In diseases like RA and SLE, the immune system mistakenly attacks the body’s own tissues.
  • Genetics: A family history of autoimmune diseases increases the risk.
  • Infections: Some diseases, like reactive arthritis, occur after bacterial or viral infections.
  • Metabolic Disorders: Gout results from uric acid metabolism dysfunction.

Risk Factors:

  1. Age:
    • Osteoarthritis is more common in older adults.
    • Autoimmune diseases like lupus are more common in young individuals.
  2. Gender:
    • Women are more likely to develop RA, lupus, and Sjogren’s syndrome.
    • Men are more prone to gout and ankylosing spondylitis.
  3. Smoking:
    • Increases the risk of RA and vasculitis disorders.
  4. Obesity:
    • Contributes to osteoarthritis by increasing joint stress.
    • Associated with metabolic diseases like gout.
  5. Dietary Factors:
    • High purine foods (red meat, alcohol) increase the risk of gout.

 

Symptoms of Rheumatological Diseases

The symptoms depend on the specific disease but commonly include:

1. Joint-Related Symptoms

  • Pain and Swelling: Seen in inflammatory and degenerative arthritis.
  • Morning Stiffness: Common in RA (lasts over 1 hour) but improves with movement.
  • Deformities: Chronic joint inflammation can lead to visible deformities.

2. Systemic Symptoms

  • Fatigue: Persistent tiredness, common in autoimmune conditions.
  • Fever: Often seen in systemic autoimmune diseases like lupus.
  • Weight Loss: Associated with inflammatory and autoimmune diseases.

3. Organ-Specific Symptoms

  • Skin Changes: Rashes in lupus, skin tightening in scleroderma.
  • Eye Involvement: Dry eyes in Sjogren’s, uveitis in ankylosing spondylitis.
  • Kidney Problems: Lupus nephritis in SLE, kidney stones in gout.

 

Investigations and Diagnosis

1. Laboratory Tests

  • Complete Blood Count (CBC): To check for anemia or infection.
  • Erythrocyte Sedimentation Rate (ESR) & C-Reactive Protein (CRP): Markers of inflammation.
  • Rheumatoid Factor (RF) & Anti-Cyclic Citrullinated Peptide (Anti-CCP): Specific for RA.
  • Antinuclear Antibody (ANA): Used to diagnose autoimmune diseases like lupus.
  • Uric Acid Levels: Elevated in gout.

2. Imaging Studies

  • X-Ray: Detects joint damage in arthritis.
  • MRI & CT Scan: Helps in soft tissue and spinal disease diagnosis.
  • Ultrasound: Used for detecting early synovitis in RA.

3. Other Specialized Tests

  • Synovial Fluid Analysis: Helps diagnose gout, infections, and inflammatory arthritis.
  • HLA-B27 Test: Used for ankylosing spondylitis.
  • Skin or Muscle Biopsy: Done in conditions like scleroderma and dermatomyositis.