Polymyalgia rheumatica

Associate Editor-In-Chief: Ujjwal Rastogi, MBBS [mailto:urastogi@perfuse.org]

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Overview
Polymyalgia rheumatica (PMR) - (in Greek meaning “pain in many muscles”) is an inflammatory condition of the muscles, which causes pain or stiffness, usually in the neck, shoulders, and hips. The pain can be very sudden, or can occur gradually over a period of time.

Most PMR sufferers wake up in the morning with pain in their muscles; however, there have been cases in which the patient has developed the pain during the evenings. Along with this disorder, there have been reports that patients who have polymyalgia rheumatica also have temporal arteritis, which causes inflammation that damages large and medium size arteries. PMR usually goes away within a year or two after treatment.

Epidemiology and Demographics

 * Mean age at onset ~ 70 (range 50-90)
 * F:M ratio = 2:1

Causes
The cause of this disorder is unknown; however, studies have shown that during this disorder, the white blood cells in the body attack the lining of muscle joints, causing inflammation. Recent studies have found that inherited factors also play a role in the probability that an individual will become sick with polymyalgia rheumatica. Several theories have included viral stimulation of the immune system in genetically susceptible individuals. Several viruses are thought to be linked to polymyalgia rheumatica, including the adenovirus, which causes respiratory infections; the human parvovirus B19, an infection that affects children; and the human parainfluenza virus.

Risk Factors
There are no certain circumstances for which an individual will get polymyalgia rheumatica, but there are a few factors that show a relationship with the disorder.
 * Usually affects adults over the age of 50
 * The average age of a person who has PMR is about 70 years old
 * Women are twice as likely to get PMR as men
 * The vast majority of people affected are white
 * 50% of people with temporal arteritis also have polymyalgia rheumatica

Diagnosis
There is no specific test to diagnose polymyalgia rheumatica. There are many other diseases which cause inflammation and pain in muscles, but there are a few tests that can help narrow down the cause of the pain. Limitation in shoulder motion, or swelling of the joints in the wrists or hands are noted by the doctor. The doctor will assess the patient’s pain, and may perform one of the following tests to determine if polymyalgia rheumatica is indeed the cause of the pain.

One test that is usually performed is the erythrocyte sedimentation rate test (also known as the ESR or SED rate), which is a blood test that checks the erythrocyte sedimentation rate. This test measures how fast the patient’s red blood cells settle in a test tube. The faster the blood cells settle, the higher the SED rate, which means that there is inflammation. Because many conditions can cause an elevated SED rate, this test alone is not a good determinant if a person has with polymyalgia rheumatica.

Another test that checks the level of C-reactive protein in the blood may also be conducted. C-reactive protein is produced by the liver in response to an injury or infection. People with polymyalgia rheumatica usually have high levels of C-reactive protein, which is a response due to inflammation.

Because people with polymyalgia rheumatica are sometimes associated with temporal arteritis, doctors may perform a test to determine if a person has temporal arteritis. A sample from the scalp artery in the temple is taken and examined under a microscope. If a person is positive for temporal arteritis, the doctor may prescribe a medicine that treats both polymyalgia rheumatica and temporal arteritis.

As a summary;


 * Age ≥ 50 at onset
 * Symtoms in ≥ 2/3 areas (shoulder girdle, hip girdle, neck) x ≥ 1 month
 * Erythrocyte sedimentation rate (ESR) ≥ 40 mm/hr
 * Exclusion of alternative diagnosis

History and Symptoms
There are a wide range of symptoms that indicate if a person has polymyalgia rheumatica. The symptoms include pain and stiffness in the muscles, usually in the neck, shoulders, and hips. The pain is moderate to severe, and may inhibit the activity of the person. These symptoms usually occur in the morning, or after sleeping. Fatigue and lack of appetite are also signs of polymyalgia rheumatica. Lack of appetite could lead to unintentional weight loss. Anemia is another sign of polymyalgia rheumatica. An overall feeling of illness and a slight fever are also signs of this disorder.

Studies have shown that about 15% of people who are diagnosed with polymyalgia rheumatica also have temporal arteritis, and about 50% of people with temporal arteritis have polymyalgia rheumatica. Some symptoms of temporal arteritis include severe headaches, scalp tenderness, jaw or facial soreness, distorted vision or aching in the limbs caused by decreased blood flow, and fatigue.


 * Symmetric aching/stiffness of axial & proximal limb musculature
 * Shoulder girdle, neck, hip girdle
 * Morning stiffness, gelling
 * Muscle strength intact, though may be limited by pain
 * Synovitis in knees, wrists, sterno-clavicular (SC) joints, hips/shoulders
 * Distal extremity swelling (tenosynovitis)
 * Malaise, fatigue, weight loss in > 50%

Relation to Giant Cell Arteritis (GCA)

 * 25% of patients with GCA have PMR as presenting symptom
 * 40-60% of patients with GCA have PMR during disease course
 * 10-15% of patients with PMR have GCA by temporal artery (TA) biopsy

Laboratory Findings

 * Mild normochromic, normocytic anemia (during active phase)
 * White blood cell (WBC) normal, platelets often increased
 * Markedly elevated ESR
 * Antinuclear antibody (ANA), rheumatoid factor (RF) usually negative
 * Creatine kinase (CK), aldolase, electromyogram (EMG), muscle biopsy all normal

Temporal Artery Biopsy

 * Not indicated if no symptoms suggestive of GCA
 * Negative predictors of GCA
 * Age < 70
 * Absence of headache or jaw claudication
 * Clinically normal temporal arteries
 * 3 negative predictors--1.7% risk GCA
 * If ≤ 2 negative predictors--55% risk GCA
 * Can still demonstrates arteritis after 2-4 weeks of steroid treatment

Differential Diagnosis

 * Rheumatoid arthritis
 * Polymyositis
 * Malignancy (myeloma, others)
 * Chronic infection (subacute bacterial endocarditis (SBE))
 * Hypothyroidism

Treatment and Medication
Anti-inflammatory medicine such as aspirin or ibuprofen is typically prescribed to treat mild cases of polymyalgia rheumatica. For more serious cases, with extreme pain and discomfort, steroids are prescribed to patients. Prednisone is the typical steroid used to treat polymyalgia rheumatica. The steroids are normally distributed in low doses (10-15 mg per day), and results are usually seen within the first few days of taking the medication. The patient's SED rate is monitored throughout the medication process, and other blood tests are conducted to make sure the patient does not experience any side effects from the treatment. Once the SED rate is back to normal, the patient will receive lower doses of the steroids in order to avoid any long term health effects from the steroids.

Some side effects from the steroids may occur. Studies have shown that steroids increase the patient’s blood pressure. For this reason, the patient’s blood pressure is monitored throughout the treatment process. Also, the steroids lower the patient’s immune system, making them more susceptible to infection. The doctor should be notified of any signs of sickness.

Along with medical treatment, patients can increase their chances of recovery by exercising and eating healthy foods. Exercise will help strengthen the weak muscles, and help to prevent weight gain. A healthy diet will help to keep a strong immune system, and also help build strong muscles and bones.

Treatment lasts as long as needed; however, it normally takes patients several years to get off of the steroids. The symptoms may come back when the dosage is lowered.

Acute Pharmacotherapies

 * NSAIDs helpful in mild disease
 * Glucocorticoids if no response to non-steriod anti inflammatory drugs (NSAIDs)
 * Prednisone 5-20 mg every day--rapid improvement in symptoms
 * Start taper after symptoms remit and ESR returns to normal (2-4 weeks)
 * Gradual dose reduction (eg, by 2.5 mg) q 1-4 weeks until dose = 5-10 mg every day
 * Even slower taper once dose < 5-10 mg (reduce dose by 1 mg q month)
 * Monitor for relapse--occurs in 25-50%, usually because taper too rapid
 * Careful observation for signs of arteritis