Restrictive Lung Diseases
Restrictive lung diseases are characterized by reduced lung volumes and impaired gas exchange, and include a wide range of conditions affecting the lung parenchyma, pleura, chest wall, or neuromuscular apparatus. 1
Interstitial Lung Diseases (ILDs)
Interstitial lung diseases represent a major category of restrictive lung diseases that affect the lung parenchyma with varying degrees of inflammation and fibrosis:
- Idiopathic Pulmonary Fibrosis (IPF) - Characterized by progressive fibrosis with UIP (usual interstitial pneumonia) pattern on histology 2
- Sarcoidosis - Granulomatous disorder that can affect multiple organs 2
- Hypersensitivity Pneumonitis - Caused by repeated inhalation of organic antigens 2, 3
- Connective Tissue Disease-Associated ILD - Occurs in conditions like:
- Systemic sclerosis
- Polymyositis/dermatomyositis
- Rheumatoid arthritis 4
- Drug-Induced ILD - Caused by medications such as amiodarone, methotrexate, and bleomycin 5
- Occupational and Environmental ILDs - Including pneumoconiosis (silicosis, asbestosis, coal worker's pneumoconiosis) 5
- Lymphangioleiomyomatosis (LAM) - Rare cystic lung disease affecting primarily women 3, 6
- Pulmonary Langerhans Cell Histiocytosis - Smoking-related disorder with nodular and cystic changes 3, 5
- Pulmonary Alveolar Proteinosis - Characterized by accumulation of surfactant proteins in alveoli 5
Chest Wall Disorders
These conditions restrict lung expansion due to abnormalities of the thoracic cage:
- Kyphoscoliosis - Spinal deformity affecting chest wall mechanics 2, 6
- Ankylosing Spondylitis - Inflammatory condition affecting spine and rib articulations 2
- Obesity Hypoventilation Syndrome - Restrictive pattern due to excess weight on chest wall 1
- Osteogenesis Imperfecta - Genetic disorder causing bone fragility and thoracic deformities 2, 3
- Post-thoracic surgery - Restriction following chest wall resection or thoracoplasty 2
Neuromuscular Disorders
These conditions cause restriction due to respiratory muscle weakness:
- Myasthenia Gravis - Autoimmune disorder affecting neuromuscular junction
- Guillain-Barré Syndrome - Acute inflammatory demyelinating polyneuropathy
- Amyotrophic Lateral Sclerosis - Progressive motor neuron disease
- Muscular Dystrophies - Including Duchenne and myotonic dystrophy 1
Pleural Disorders
- Pleural Effusion - Fluid accumulation restricting lung expansion
- Pleural Fibrosis - Scarring of the pleura following inflammation
- Pneumothorax - Air in pleural space causing lung collapse
Other Causes
- Pulmonary Edema - Fluid in lung tissue causing restriction
- Acute Respiratory Distress Syndrome (ARDS) - Diffuse alveolar damage with edema
- Post-COVID-19 Fibrosis - Emerging cause of restrictive lung disease
- Combined Pulmonary Fibrosis and Emphysema (CPFE) - Mixed restrictive and obstructive pattern 3
Clinical Implications
Patients with restrictive lung diseases typically present with:
- Dyspnea, particularly with exertion
- Reduced exercise tolerance
- Dry cough
- Fatigue
- Reduced quality of life 1, 7
Pulmonary function tests show reduced lung volumes (TLC, FVC) with preserved or increased FEV1/FVC ratio. DLCO is often reduced, particularly in ILDs with significant fibrosis 3, 1.
The prognosis varies widely depending on the specific disease, with some conditions like IPF having a poor prognosis (median survival 2-3 years without treatment) while others may be stable or even reversible with appropriate management 4, 7.
Management approaches differ based on the underlying cause but may include immunosuppressive therapy, antifibrotic medications, oxygen therapy, pulmonary rehabilitation, and in selected cases, lung transplantation 1, 7.
For accurate diagnosis and optimal management, comprehensive evaluation with pulmonary function testing, chest imaging (particularly HRCT), and in some cases, lung biopsy is essential 3, 7.