Epidemiology

• Prevalence: affects 0.05-1.5% of the population
• Age: usually occurs in <40 y/o’s
• Sex: M:F ratio is 10:1
  • Females tend to have milder and more peripheral disease with fewer radiographic changes in spine
• Race: rare in non-whites
• Genetic Factors: >90% of whites with ankylosing spondylitis are HLA-B27 positive

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Physiology

• Immunologic Mechanism
• Cardinal Site of Disease: vertebral column -> leads to development of fibrosis and ossification -> eventual ankylosis of vertebral joints
• Decreased Ventilation to Lung Apices: may predispose changes that develop in this area

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Diagnosis

• Spine X-Rays: bilateral sacroiliitis

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Clinical Manifestations

Cardiovascular Manifestations

• Conduction Defects (see Heart Blocks, [[Heart Blocks]])
• Aortitis/Aortic Insufficiency (see Aortic Insufficiency, [[Aortic Insufficiency]])

Ophthalmologic Manifestations

• Uveitis (see Uveitis, [[Uveitis]])
• Conjunctivitis (see Conjunctivitis, [[Conjunctivitis]])

Pulmonary Manifestations (typically insidious onset)

Apical Interstitial Lung Disease with or without Apical Fibrobullous Disease

• Epidemiology
  • Apical interstitial lung disease is the most common pattern of lung involvement: 30% of cases have upper zone fibrosis
    • Fibrobullous changes are less common, being seen in 1-2% of cases
    • Apical interstitial changes usually progress to fibrobullous changes over time
  • Although usually occurs in long-standing ankylosing spondylitis cases, subclinical pulmonary involvement is common early in the course of the disese
• Diagnosis
  • CXR/Chest CT: apical reticulonodular infiltrates or fibrobullous changes (often mimicking those seen in TB): usually bilateral
    • Apices may be secondarily infected or retracted
  • FOB: subclinical lymphocytic alveolitis may be seen
  • Open Lung Biopsy
    • Pneumonic-like process: patchy round cell or fibroblastic infiltration progressing to extensive fibrosis
    • Dense pleural fibrosis is usually associated with parenchymal fibrosis
    • Bronchiectasis: may be seen
    • Bullous changes may be seen
• Clinical
  Asymptomatic or may present with cough, sputum, dyspnea, absence of clubbing
  • Pulmonary Superinfection (with TB, atypical mycobacteria, or Aspergillus fumigatus): may complicate the apical fibrobullous changes
    • Aspergillus fumigatus is isolated from 60% of cases with apical cavitation
  • Hemoptysis: may result from apical cavitary disease
• Treatment
  • No treatment has been proven to prevent apical fibrosis: it is typically resistant to corticosteroid therapy
  • Bronchial artery embolization: may be necessary to control hemoptysis
  • Avoid surgial resection of Aspergilloma unless bleeding is refractory: due to high risk of post-op bronchopleural fistula and empyema

Pleural Disease

• Clinical
  • Apical Pleural Thickening: early finding in ankylosing spondylitis
  • Pleural Calcifications
  • Pleural Effusion (see Pleural Effusion-Exudate, [[Pleural Effusion-Exudate]]): rare
    • Usually exudate with normal glucose (but empyema has been reported)
  • Pleuritis

Spontaneous Pneumothorax (see Pneumothorax, [[Pneumothorax]])

• Physiology: may occur due to rupture of apical bullae

Atelectasis (see Atelectasis, [[Atelectasis]])

• xxx

Chronic Aspiration Pneumonia (see Aspiration Pneumonia, [[Aspiration Pneumonia]]):

• xxx

Thoracic Cage Immobility

• Physiology: costovertebral spondylosis (which may occur in advanced cases)
• Diagnosis
  • ABG: minimal gas exchange abnormalities
  • PFT’s: fixation of thorax at high volume and decreased chest wall compliance (although ankylosing spondylitis generally does not usually lead to significant pulmonary dysfunction)
    • Expiratory flow rates: normal
    • TLC (and VC): slight-moderate decrease
    • FRC and RV: normal-slightly increased
• Clinical
  • Acute/Chronic Hypoventilation (see Acute Hypoventilation, [[Acute Hypoventilation]] and Chronic Hypoventilation, [[Chronic Hypoventilation]]): may occur in conjunction with parenchymal lung disease (pneumonia, etc)

Bronchocentric Granulomatosis (see Bronchocentric Granulomatosis, [[Bronchocentric Granulomatosis]])

• xxx

Scar Lung Carcinoma (see Lung Cancer, [[Lung Cancer]])

• Clinical
  • Adenocarcinoma
  • Squamous Cell Carcinoma

Mediastinal Fibrosis (see xxxx, [[xxxx]])

• xxx

Cricoarytenoid Arthritis (see Cricoarytenoid Arthritis, [[Cricoarytenoid Arthritis]]): has been reported

• Clinical
  • Upper Airway Obstruction
  • Acute Respiratory Failure
  • Cor Pulmonale

Renal Manifestations

• Chronic Prostatism

Rheumatologic Manifestations

• Arthritis of Peripheral Joints (see Arthritis, [[Arthritis]]): 33% of cases
• Atlantoaxial Instability (see Atlantoaxial Instability, [[Atlantoaxial Instability]])
• Spine Arthritis (see Arthritis, [[Arthritis]]): back pain and morning stiffness (that improves with exercise) are common

Other Manifestations

• Fatigue (see Fatigue, [[Fatigue]])
• Low-Grade Fever (see Fever, [[Fever]])
• Weight Loss (see Weight Loss, [[Weight Loss]])

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Treatment

• Corticosteroids (see Corticosteroids, [[Corticosteroids]])
  • Pulmonary apical fibrotic changes are typically steroid-resistant

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References

• Pulmonary involvement in ankylosing spondylitis. Ann Rheum Dis. 1986 September; 45(9): 736–740
• Lung findings on high-resolution computed tomography in idiopathic ankylosing spondylitis–correlation with clinical findings, pulmonary function testing and plain radiography. Rheumatology (1997) 36 (6): 677-682