USMLE Guide: Polymyalgia Rheumatica

Introduction

Polymyalgia Rheumatica (PMR) is a common inflammatory disorder primarily affecting individuals over the age of 50. It is characterized by pain and stiffness in the shoulders, neck, and pelvic girdle, often leading to significant functional impairment. In this USMLE guide, we will explore the key aspects of PMR, including its clinical presentation, diagnosis, and management.

Clinical Presentation

1. Symptoms: Patients with PMR commonly complain of the following:

   • Bilateral shoulder pain and stiffness, typically worse in the morning or after prolonged inactivity.
   • Neck pain and stiffness.
   • Hip and pelvic girdle pain and stiffness.
   • Generalized fatigue and malaise.

2. Physical Examination Findings: The following clinical signs may be observed:

   • Decreased active and passive range of motion in affected joints.
   • Tenderness over the affected areas.
   • No significant joint swelling or deformity.
   • No systemic inflammatory signs, such as fever or weight loss.

Diagnosis

1. Clinical Criteria: PMR is diagnosed based on the following criteria:

   • Age ≥ 50 years.
   • Bilateral shoulder pain.
   • Morning stiffness lasting at least 45 minutes.
   • Elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) levels.

2. Laboratory Investigations: The following tests aid in the diagnosis and exclusion of other conditions:

   • ESR and CRP: Typically elevated in PMR.
   • Complete blood count (CBC): Normal or mildly elevated white blood cell count.
   • Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) antibodies: Usually negative, helping differentiate from rheumatoid arthritis.

3. Imaging Studies: Although not diagnostic, imaging can rule out other conditions and assess for complications:

   • X-rays: Usually normal in PMR but may show degenerative changes associated with age.
   • Ultrasound or MRI: Can detect bursitis or tenosynovitis, aiding in diagnosis.

Management

1. Glucocorticoids (GCs): The mainstay of PMR treatment is oral GCs, usually prednisone.

   • Initial dose: Prednisone 10-20 mg/day.
   • After symptom improvement (usually within 1-4 weeks), gradually taper the dose to the lowest effective dose (usually 5-10 mg/day).
   • Treatment duration: Typically 12-24 months, but some patients may require longer therapy.

2. Monitoring: Regular follow-up is essential to assess disease activity and monitor for complications:

   • ESR or CRP: Serial measurements help evaluate response to treatment.
   • Bone mineral density (BMD): Long-term GC use can lead to osteoporosis, so BMD assessments are recommended.

3. Complications: PMR may be associated with temporal arteritis (giant cell arteritis). Watch for signs such as headache, jaw claudication, and visual disturbances. If suspected, immediate treatment with high-dose GCs is necessary to prevent vision loss.

Conclusion

Polymyalgia Rheumatica is an inflammatory disorder commonly seen in individuals over the age of 50. Recognizing its clinical presentation, employing appropriate diagnostic criteria, and initiating proper management with glucocorticoids are crucial in providing effective care for patients with PMR. Regular monitoring and vigilance for complications, such as temporal arteritis, are vital for optimal patient outcomes.