Polymyalgia rheumatica

Polymyalgia rheumatica is an inflammatory disorder that primarily affects older adults, causing pain and stiffness in the shoulders, hips, and neck. It is closely associated with systemic symptoms such as fatigue and low-grade fever, and early recognition is essential to prevent complications. Understanding its definition, classification, and clinical features is important for accurate diagnosis and management.

Definition and Classification

Definition

Polymyalgia rheumatica (PMR) is an inflammatory condition characterized by proximal muscle pain and stiffness, particularly affecting the shoulder and pelvic girdles. It is considered an immune-mediated disorder, and symptoms typically develop rapidly over days to weeks. The condition is often accompanied by elevated inflammatory markers and can significantly impair daily activities.

Classification

PMR can be categorized based on clinical presentation and association with other conditions:

• Classic PMR: Symmetric proximal muscle pain and stiffness without associated vasculitis.
• PMR associated with giant cell arteritis (GCA): Presents with typical PMR symptoms along with features of vascular inflammation such as headache, jaw claudication, and visual disturbances.
• Overlap with other rheumatologic conditions: PMR can coexist with rheumatoid arthritis or other connective tissue disorders, requiring careful differentiation.

Etiology and Pathophysiology

Etiology

• Genetic predisposition: Certain HLA alleles may increase susceptibility to PMR.
• Environmental triggers: Infections or other immune stimuli may precipitate disease onset.
• Immune-mediated mechanisms: Dysregulated immune responses and cytokine activation play a central role in inflammation.

Pathophysiology

PMR involves inflammation of synovial and periarticular structures, including bursae and tendon sheaths. Elevated levels of pro-inflammatory cytokines such as interleukin-6 contribute to systemic symptoms and local musculoskeletal inflammation. In cases associated with giant cell arteritis, vascular inflammation of large and medium arteries may occur, increasing the risk of serious complications such as vision loss.

Clinical Features

Musculoskeletal Symptoms

• Proximal muscle pain and stiffness: Affects shoulders, hips, and neck, often worse in the morning.
• Morning stiffness: Lasts for at least 30 minutes and can interfere with daily activities.
• Functional impairment: Difficulty dressing, rising from a chair, or lifting objects due to pain and limited range of motion.

Systemic Symptoms

• Fatigue and malaise: Generalized tiredness is common and can be profound.
• Low-grade fever and weight loss: May accompany inflammatory flares.
• Headaches or visual disturbances: Suggestive of concomitant giant cell arteritis and require urgent evaluation.

Diagnosis

Clinical Evaluation

• Detailed history focusing on sudden onset of symmetric proximal pain and stiffness.
• Physical examination assessing range of motion, tenderness, and signs of temporal artery involvement.

Laboratory Investigations

• Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) indicate systemic inflammation.
• Exclusion of other inflammatory, infectious, or malignant causes is essential for accurate diagnosis.

Imaging

• Ultrasound of shoulders and hips can reveal bursitis, tenosynovitis, or joint effusions.
• MRI or PET-CT may be used in selected cases to assess inflammation or rule out alternative diagnoses.

Differential Diagnosis

• Rheumatoid arthritis
• Osteoarthritis
• Fibromyalgia
• Inflammatory myopathies

Management

Pharmacological Treatment

• Glucocorticoids: First-line therapy; low-dose prednisone typically leads to rapid symptom improvement.
• Adjunctive therapies: Methotrexate or biologic agents may be considered in patients with relapsing or refractory disease.
• Management of side effects: Measures to prevent osteoporosis, monitor blood glucose, and reduce infection risk are essential during long-term steroid therapy.

Non-Pharmacological Management

• Physical therapy to maintain mobility, muscle strength, and joint function.
• Patient education on activity modification, energy conservation, and recognition of relapse symptoms.

Prognosis

The prognosis of polymyalgia rheumatica is generally favorable, with most patients responding rapidly to glucocorticoid therapy. Relapses can occur, particularly during dose tapering, and some individuals may require prolonged treatment. Chronic complications are uncommon but may include steroid-related adverse effects and, in cases associated with giant cell arteritis, risk of vision loss or vascular events. Early recognition, appropriate therapy, and monitoring can optimize functional outcomes and quality of life.

Complications

• Giant cell arteritis: Occurs in a subset of patients and can lead to serious complications such as vision loss, stroke, or aortic aneurysm if untreated.
• Glucocorticoid-induced adverse effects: Long-term steroid therapy may cause osteoporosis, diabetes, hypertension, cataracts, and increased infection risk.
• Functional disability: Persistent stiffness or pain can impair daily activities and reduce quality of life, especially in elderly patients.

Recent Advances and Research

• Role of IL-6 inhibitors: Tocilizumab and other biologics targeting interleukin-6 are being studied for steroid-sparing effects and management of refractory PMR.
• Biomarkers for disease activity: Research is focused on identifying laboratory or imaging markers to predict relapse and guide therapy tapering.
• Imaging advances: Musculoskeletal ultrasound, MRI, and PET-CT are increasingly used for early diagnosis, monitoring response to therapy, and detecting subclinical vascular inflammation.

References

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