Overview
Rheumatic polymyalgia (PMR), first reported by Barber et al. in 1957, is the most common inflammatory rheumatic disease in older Caucasians and often requires long-term glucocorticoid therapy. Although the symptoms are characteristic, other autoimmune, infectious, endocrine, and malignant diseases may also present with similar symptoms. The course of the disease is heterogeneous and unpredictable, and approximately 30% of patients may have a combination of giant cell arteritis. Although glucocorticoids rapidly improve symptoms in most patients, they may also cause serious adverse effects.
PMR often occurs in patients over 50 years of age, but rarely in patients under 50 years of age, and the ratio of men to women is 1:2. The onset of the disease is acute or subacute.
Pathogenesis
The etiology of rheumatic polymyalgia remains unknown, although genetic and environmental factors are associated with susceptibility and severity of the disease. Some studies have shown that the disease occurs in a cyclic pattern, suggesting that environmental factors such as infections such as B19, Mycoplasma pneumoniae and Chlamydia pneumoniae, may act as triggering mechanisms.
Clinical manifestations
1. Severe pain in the neck, shoulder girdle and pelvic girdle muscles
Myalgia is the most prominent symptom of PMR, some patients have pain so severe that they cannot turn over and breathe deeply, it can be sudden onset, and most of them gradually worsen within a few weeks. Although myalgia is obvious, muscle pressure pain is not obvious.
2, morning stiffness, stiffness after inactivity (jelly phenomenon) stiffness after rest and morning stiffness that lasts for more than 1h are typical symptoms. In severe cases, there are difficulties in combing hair, shaving, dressing, squatting and going up and down stairs.
3, arthralgia, previously thought that arthralgia in PMR is not common, but recent studies have shown that PMR arthralgia is not uncommon, with large joints such as shoulder, knee, wrist common, sternoclavicular joint involvement is also quite a lot, manifested as tendonitis, synovitis, the primary PMR generally does not cause joint destruction. However, Paice et al. found that 11 of 25 cases of PMR had erosion and destruction of the sternoclavicular joint, the majority of which were bilateral and appeared in patients who had PMR for more than 6 months. A multicenter study showed that mild to moderate synovitis in PMR mainly affects the proximal joints, with the spine and limb bands being the most commonly involved, and 15% to 50% have peripheral joint synovitis, with the knee and wrist joints being the most common. PMR with peripheral arthritis and rheumatoid arthritis (RA) with PMR-like symptoms as the first episode are easily misdiagnosed.
4, systemic symptoms, most patients have systemic symptoms, especially at the beginning of the disease, including weakness, loss of appetite, loss of body mass, hypothermia, and occasionally depression.
Auxiliary examination
1. Mild to moderate orthocytic orthochromic anemia may be present
2. Blood sedimentation is significantly increased (<50 mm/h by Weiss method), and C-reactive protein is increased and consistent with disease activity.
3. Liver enzymes may be mildly elevated, but serum myosin, which reflects transverse muscle inflammation, is mostly within the normal range.
4, electromyography and muscle biopsy are not based on inflammatory myopathy
5.Anti-nuclear antibody and other autoantibodies and rheumatoid factor are usually negative
6, there may be a small amount of synovial fluid in the shoulder, knee or hip joint as a non-specific inflammatory response
Diagnosis
The diagnosis of rheumatic polymyalgia mainly relies on clinical manifestations, and there are 6 diagnostic criteria.
① Age of onset > 50 years
② at least 2 muscle pains and morning stiffness in the neck, scapular girdle and pelvic girdle area for ≥ 4 weeks
③ ESR and (or) CRP elevation
④Small dose of hormone (prednisone ≤15mg/d) is effective;
⑤ no muscle weakness or muscle atrophy and muscle redness and heat
⑥Exclude other lesions similar to rheumatic polymyalgia such as RA, myositis, tumor and infection
The diagnosis of rheumatic polymyalgia can be confirmed if all 6 conditions are met.
Differential diagnosis
1. Rheumatoid arthritis of elderly onset: morning stiffness, symmetrical small joint swelling and pain, deformity, positive rheumatoid factor, etc. Rheumatic polymyalgia without small joint synovitis (although there is joint swelling) without erosive or destructive lesions, negative rheumatoid factor and no rheumatoid nodules, etc., according to which it can be differentiated from rheumatoid arthritis.
2, polymyositis: this disease is also seen in elderly women, with proximal limb with muscle weakness and pain, muscle strength significantly weakened, increased blood sedimentation, increased serum muscle enzyme activity, electromyography shows myogenic damage, muscle biopsy has myositis characteristics, according to which can be distinguished from rheumatic polymyalgia.
Fibromyalgia syndrome: This syndrome is characterized by extra-articular musculoskeletal stiffness and fatigue, with fixed sensitive pressure points on the extremities of the body, such as the occipital attachment point of the cervical muscle, the middle of the upper trapezius; the lateral aspect of the junction of the second rib and cartilage of the pectoral muscle, 2 cm below the external upper ankle, the upper hip, 2 cm after the greater trochanter, the medial goose bursa area of the knee joint, the gastrocnemius Achilles tendon exchange, etc., with sleep disturbances, often accompanied by It is often accompanied by irritable enteritis, irritable cystitis, tension and headache, menstrual disorders and insensitivity to steroidal or non-steroidal anti-inflammatory drugs, normal blood sedimentation, etc.
4. Hypothyroidism may be manifested by myalgia, but thyroid function tests should be abnormal
Treatment
1, good response to glucocorticoid treatment can be used as a diagnostic treatment indicator. Generally, 10~20mg/d of prednisone is used, and the symptoms are significantly reduced within the next day or several days. If there is still no efficacious response in 1~2 weeks, attention should be paid to the coexistence with giant cell arteritis (GCA ), or other diagnoses should be considered. In patients who respond to prednisone treatment, dose reduction can be initiated after 2-4 weeks of maintenance, and the total efficacy is determined by the withdrawal response; a small number of patients must be maintained on low doses (7.5 mg/d 1-2) for 1-2 years. Mild cases can be treated with NSAIDs such as anti-inflammatory pain and aspirin, but they are not as effective as low-dose corticosteroids.
However, long-term hormone application, 25% of patients will have different side effects, such as spinal compression fracture, aseptic necrosis of femoral head, hypertension, diabetes, cataract, infection, etc., and should be routinely treated with calcium supplementation.
Patients with poor therapeutic effect can be combined with immunosuppressants, such as methotrexate (MTX) 7.5~15 mg per week intramuscularly or orally, or cyclophosphamide (CTX) 50~100 mg・d-1 orally or 0.5~0.8g・m-2 once a month intravenously, with regular review of blood leukocytes. The combination of immunosuppressant can reduce the amount of hormone and the recurrence of the disease.
3, 10%-20% of PMR patients with non-steroidal anti-inflammatory drugs can control the disease, such as 1-2 weeks with non-steroidal anti-inflammatory drugs is not effective should be timely hormone therapy. PMR that is not well controlled by small doses of hormones can be combined with non-steroidal anti-inflammatory drugs. However, for older patients or patients with gastroduodenal lesions, they should be alert to the occurrence of serious side effects in the gastrointestinal tract, such as ulcers, bleeding and perforation. Therefore, NSAIDs should not be used routinely, let alone long-term like hormones, and proton pump inhibitors such as omeprazole and H2 receptor blockers for the prevention of GI side effects.
Effective criteria for clinical treatment
Decrease in C-reactive protein concentration or (and) sedimentation, improvement in morning stiffness, upper extremity elevation over the shoulder up to the patient’s baseline activity level prior to the onset of polymyalgia symptoms, and improvement in the patient’s and physician’s overall assessment of disease activity. Patients should be followed regularly for at least 1 year.
Prognosis
Recurrence and remission of PMR often alternate, and some patients have a self-limiting condition. In recent years, due to early diagnosis and treatment, the mortality rate of PMR in elderly patients with GCA is not different from that of normal people of the same age. In the later stages of the disease, serious conditions such as muscle wasting atrophy or shoulder capsular contracture may also occur.