Polymyalgia rheumatica

Polymyalgia rheumatica is a disease that causes pain and stiffness in proximal muscle groups (primarily the neck, shoulders, and hips), accompanied by nonspecific general symptoms.

It is a rheumatic disease very similar to others, making differential diagnosis essential for appropriate treatment.

The causes of polymyalgia rheumatica are unknown.

In some patients, polymyalgia rheumatica is a manifestation of underlying giant cell arteritis (also called temporal arteritis).

Related genetic and environmental factors have been identified, including:

• Genetic predisposition involving certain genes such as HLA-DRB1 04, ICAM-1 and RANTES polymorphisms, and IL-1.
• The presence of certain seasonal patterns suggests an infectious trigger, which could include, for example, Mycoplasma pneumoniae, parvovirus B19, and Epstein-Barr virus.
• Other associations have been made with changes in the microbiota (microorganisms that normally live in the body), for example, in people with diverticulitis, and even with adjuvants in some vaccines (ASIA syndrome).

Risk factors for developing polymyalgia rheumatica include:

• Advanced age.
• Female sex.
• Caucasian race originating from Northern Europe.

Polymyalgia rheumatica is most common in individuals over 50 years of age. It is more frequent in women than in men, at a ratio of approximately 2 to 1.

The estimated annual incidence is 50 to 100 cases per 100,000 inhabitants among people over 50 years of age.

Between 16% and 21% of people with polymyalgia rheumatica develop giant cell arteritis, and between 35% and 50% of those with giant cell arteritis also develop polymyalgia rheumatica.

Polymyalgia rheumatica is characterized by:

• Pain and stiffness in the neck muscle.
• Pain and stiffness in the thoracic and pelvic girdles: both shoulders or both hips may be painful.
• Sometimes pain or stiffness in the wrists, elbows, and knees.
• Prolonged morning stiffness.
• Stiffness after inactivity.
• Fever.
• Asthenia (weakness).
• Loss of appetite (anorexia).
• Depression.
• Weight loss.

Functional complications affect basic activities such as getting out of bed or a chair, getting in or out of a car, bathing, combing hair, and dressing, thereby impacting social interaction, physical activity, sleep, and overall well-being.

A doctor should be consulted if the pain or stiffness is new, disrupts sleep, or limits usual activities.

If giant cell arteritis is present, other symptoms may occur, such as:

• Headache.
• Jaw claudication (difficulty opening the mouth).
• Scalp tenderness in the temporal area (near the temples).
• Vision loss, with a risk of blindness if left untreated.

Polymyalgia rheumatica should be suspected in older adults with bilateral shoulder and hip pain and stiffness, worse in the morning, along with inflammatory markers such as an elevated erythrocyte sedimentation rate (ESR), often around 100 mm/hour, and a positive C-reactive protein (CRP).

Other laboratory findings include:

• Normochromic and normocytic anemia may be present.
• Occasional thrombocytosis (increased platelet count).
• Typical autoantibodies (ANA, RF, anti-CCP) are negative.
• Diagnostic imaging such as ultrasound and magnetic resonance imaging (MRI) can detect subdeltoid bursitis, shoulder and hip synovitis, and tenosynovitis, helping to differentiate it from other diseases. Other imaging modalities, such as fluorodeoxyglucose positron emission tomography (FDG-PET), may show involvement of the shoulders, greater trochanter, and sternoclavicular joints.
• There are no signs of myopathy on EMG (electromyography) or muscle biopsy.

Currently, the 2012 ACR/EULAR criteria (age over 50, bilateral shoulder pain, elevated ESR/CRP, and a score based on physical examination findings and ultrasound) are used to classify the disease, but not to diagnose it.

The diagnosis of polymyalgia rheumatica is usually made after ruling out other diseases, especially:

• Late-onset rheumatoid arthritis.
• Spondyloarthritis.
• Seronegative symmetric synovitis (RS3PE).
• Crystalline arthropathies.
• Muscle diseases (including statin toxicity).
• Other connective tissue diseases.
• Non-inflammatory causes such as osteoarthritis, spinal stenosis, Parkinson's disease, and tumors.

If giant cell arteritis is suspected, a temporal artery biopsy is indicated.

In polymyalgia rheumatica, the goal of treatment is to improve mobility and reduce pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) may be used for this purpose, although they are not routinely recommended. Treatment primarily consists of administering low doses of corticosteroids, starting with 10–20 mg/day of prednisone.

As symptoms subside, and regardless of the erythrocyte sedimentation rate (ESR), the corticosteroid dose is reduced to the lowest effective dose while minimizing adverse effects (weight gain, osteoporosis, high blood pressure, diabetes, cataracts).

Most patients remain off corticosteroids after two years, but some require low doses for several years.

Many need treatment for more than a year, with frequent monitoring. Calcium (1000–1200 mg/day) and vitamin D (600–800 IU/day) supplements are recommended if corticosteroids are used for more than 3 months, with or without bisphosphonates, to prevent corticosteroid-induced osteoporosis.

In selected patients at high risk of relapse or corticosteroid toxicity, or with a poor response, methotrexate may be added as a steroid-sparing agent. Leflunomide and azathioprine may also be used in some patients.

Tumor necrosis factor (TNF) blockers are not recommended.

Interleukin-6 (IL-6) blocking agents, such as tocilizumab (and more recently sarilumab), have shown utility as steroid-sparing agents in people who do not respond to or are intolerant of corticosteroids.

Physical therapy may be helpful if deconditioning has occurred. In addition, the following self-care guidelines are recommended:

• Healthy diet.
• Regular exercise.
• Use of assistive devices for daily activities, if necessary.
• Education and psychosocial support.

For appointments, it is suggested to prepare a list of symptoms, current medications, and key questions.

The doctor will inquire about the location and intensity of pain, stiffness, functional impact, and possible signs of giant cell arteritis.

If giant cell arteritis is suspected, high-dose prednisone prescribed by a specialist should be started immediately to prevent blindness.