Wind-dampness myalgia is commonly seen in the elderly and is a syndrome characterized clinically by persistent pain and stiffness in the neck, shoulder girdle, and pelvic girdle muscle groups [1].

bubble_chart Clinical Manifestations

PMR commonly occurs in individuals over 50 years old, and is rare in patients under 50. The male-to-female ratio is 1:2. The prevalence in our country is unclear. A report from the United States indicates an annual incidence of 54 per 100,000 and a prevalence of 500 per 100,000 in the population aged 50 and above^[2].

PMR has an insidious onset, with systemic symptoms such as low-grade fever, lack of strength, fatigue, and weight loss. The typical clinical manifestations include symmetrical pain and stiffness in the neck, shoulder girdle, or proximal pelvic muscles. It may also present unilaterally or be limited to specific muscle groups. Stiffness and pain are most noticeable in the morning or after periods of rest. In acute cases, patients may report feeling relatively normal at bedtime but waking up with severe pain and stiffness. In severe cases, activities such as combing hair, shaving, dressing, squatting, or climbing stairs become difficult. These mobility issues are not primarily due to muscle weakness, as seen in polymyositis, where muscle strength is significantly reduced, but rather result from muscle and joint stiffness and pain, which may gradually improve with activity. Regardless of the complaints, physical examination findings are often minimal, possibly revealing grade I anemia, mild tenderness or swelling in the shoulder or knee joints, or slight signs of synovial effusion. Arthroscopic examination may confirm the presence of synovitis^[3]

bubble_chart Auxiliary Examination

The most prominent laboratory abnormalities in PMR are an elevated erythrocyte sedimentation rate (40–50 mm/h) and increased C-reactive protein levels. Rheumatoid factor, antinuclear antibodies, blood moistening and tonifying substances, and serum muscle enzyme activities are all normal. Electromyography shows no signs of myogenic or neurogenic damage.

bubble_chart Diagnosis

PMR is a clinical syndrome. After excluding other wind-dampness diseases, the diagnosis can be made based on the following clinical manifestations: elderly patients over 50 years old; stiffness and pain in the neck, shoulders, lower back, or whole body lasting for more than 4 weeks; ESR > 40mm/h; and a good response to low-dose corticosteroid therapy.

It must be differentiated from the following Bi diseases: ① Elderly-onset wind-dampness arthritis: characterized by morning stiffness, symmetrical swelling and pain in small joints, deformities, and positive wind-dampness factor. ② Polymyositis: This disease is also more common in elderly women, presenting with proximal limb girdle muscle weakness and pain, significantly reduced muscle strength, and elevated ESR. However, this disease is characterized by myositis, increased serum muscle enzyme activity, myogenic damage on electromyography, and muscle biopsy showing features of myositis. ③ Fibrositis syndrome: This syndrome typically manifests as extra-articular musculoskeletal stiffness, pain, and fatigue, with fixed tender points in the body and limbs, such as the attachment points of the neck muscles at the occiput, the middle of the upper trapezius; the lateral side of the second rib and cartilage junction, 2 cm below the lateral epicondyle, the upper buttock, 2 cm posterior to the greater trochanter, the medial knee goose-foot bursa area, and the gastrocnemius tendon junction (8 points in total). It is often accompanied by sleep disorders, irritable bowel syndrome, irritable bladder syndrome, tension headache, menstrual irregularities, and poor response to steroid or non-steroidal anti-inflammatory drugs, with normal ESR.

PMR responds well to glucocorticoid therapy, which can serve as a diagnostic treatment indicator. Generally, prednisone 10–20 mg/d is administered, and symptoms significantly improve the next day or within a few days. If there is no therapeutic response after 1–2 weeks, attention should be paid to possible coexistence with GCA or consideration of other diagnoses. For patients who respond to prednisone treatment, the dose can usually be tapered after maintaining for 2–4 weeks, with the total treatment efficacy determined by withdrawal response. A small number of patients may require low-dose (7.5 mg/d) maintenance therapy for 1–2 years. Mild cases may be treated with nonsteroidal anti-inflammatory drugs such as indomethacin or aspirin, but these are less effective than low-dose corticosteroids^[1].