Polymyalgia rheumatica (PMR) is a relatively common inflammatory condition that primarily affects the muscles and joints. It causes significant pain and stiffness, which can severely limit daily activities. PMR is almost exclusively found in older adults, typically those over the age of 50, with the average age of diagnosis being around 70 years old. While the exact cause remains unknown, this inflammatory disorder impacts the body through a distinct and recognizable set of physical and biological changes.
How Polymyalgia Rheumatica Affects the Body
The most noticeable impact of polymyalgia rheumatica is the onset of severe, symmetrical aching and stiffness in specific regions of the body. The discomfort is concentrated in the “girdles”: the shoulder girdle (neck and upper arms) and the pelvic girdle (hips, buttocks, and thighs). This pain often develops quickly, sometimes over a few days or weeks, and affects both sides of the body simultaneously.
The defining feature of this condition is the profound stiffness experienced, especially after periods of inactivity. This stiffness is characteristically worst in the morning, often lasting for more than 45 minutes, making simple tasks like getting out of bed or raising the arms challenging. Although the stiffness tends to improve slightly with movement throughout the day, the pain and limited range of motion can make routine activities difficult.
Beyond the musculoskeletal symptoms, PMR often presents with systemic or constitutional symptoms that reflect the body-wide inflammatory state. Patients may experience overwhelming fatigue, a general feeling of being unwell known as malaise, and sometimes a mild fever. Loss of appetite and unexplained weight loss are also common, further underscoring the systemic nature of the condition.
The Inflammatory Process Behind PMR
The symptoms of PMR arise from a systemic inflammatory response, although the precise trigger for this process is still under investigation. It is considered an immune-mediated disorder where the body’s immune system appears to mistakenly target and inflame healthy tissues in the body. This inflammatory activity is concentrated in the joints and surrounding structures, specifically the bursae and synovium of the shoulder and hip girdles.
The inflammation is driven by the release of specific signaling proteins known as cytokines. Research has highlighted a significant increase in the circulating levels of the cytokine Interleukin-6 (IL-6) in individuals with active PMR. This protein acts as a potent messenger, orchestrating the inflammatory cascade that results in the pain and stiffness experienced in the affected areas.
Although the muscles themselves are not the primary site of inflammation, the surrounding tissue structures, such as the fluid-filled sacs (bursae) and the lining of the joints (synovium), become inflamed. This periarticular inflammation is what causes the intense aching and stiffness felt in the muscles of the shoulders, neck, and hips. The systemic release of inflammatory markers, like IL-6, also accounts for the constitutional symptoms such as fever and fatigue.
Identifying Polymyalgia Rheumatica
Diagnosing polymyalgia rheumatica is a clinical process that relies on a combination of factors, as there is no single definitive test. A physician first assesses the patient’s age and the characteristic clinical presentation, including the bilateral shoulder and hip aching and morning stiffness lasting longer than 45 minutes.
Laboratory tests are then used to confirm the presence of systemic inflammation and to help exclude other conditions. The two primary blood markers measured are the Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP). Both of these markers are typically elevated in PMR, indicating the presence of an acute-phase reaction, though CRP is considered a more sensitive indicator of disease activity.
The diagnostic process also involves ruling out other diseases that can mimic PMR, such as rheumatoid arthritis or hypothyroidism. This is known as differential diagnosis, and it requires additional blood tests to check for specific autoantibodies. In some cases, imaging like ultrasound may be used to identify inflammation in the bursae and tendons of the shoulders and hips, which further supports the diagnosis.
Managing the Effects of PMR
The standard and most effective treatment for managing polymyalgia rheumatica is the use of corticosteroids. These anti-inflammatory medications, such as prednisone, work by rapidly suppressing the systemic inflammation responsible for the symptoms. Patients often experience a dramatic and swift improvement in pain and stiffness, sometimes within 24 to 72 hours of starting treatment.
Treatment requires a long-term commitment, typically lasting one to two years or longer, to prevent the disease from returning. After the initial symptoms are controlled, the corticosteroid dose is slowly and gradually reduced in a process called tapering. This slow reduction is necessary to minimize the risk of a relapse and to reduce side effects associated with prolonged use.
Individualized care and close monitoring are essential throughout the treatment period. If symptoms recur during the tapering process, the dose is temporarily increased before resuming the slow reduction. Physical therapy and exercise can also serve as supportive measures, helping to maintain muscle strength and joint mobility during the course of the disease.