A disease with the name polymyalgia rheumatic sounds rare and serious. But it affects over 700,000 Americans and is very treatable.
Polymyalgia rheumatica (PMR) was first diagnosed in 1888. It's a painful, sometimes disabling, condition that can be associated with giant cell arteritis (GCA). This disease is much less common, but much more serious than PMR.
Let's take a look at these two conditions and their treatments.
The first part of the disorder's name reflects its main symptom — muscle pain (myalgias) in several locations (the "poly").
The second part of the name, rheumatica, comes from the joint inflammation that's responsible for the pain.
Most patients with PMR locate their pain in muscles. But the inflammation is actually most intense in the membranes surrounding the joints in the painful regions, and in the fluid-filled sacs that cushion these joints. Unlike rheumatoid arthritis, PMR never leads to joint damage and destruction.
Doctors don't know for sure what causes PMR. They believe it's an autoimmune disorder that develops when the body's powerful immune system turns against itself. This produces inflammation by "friendly fire."
Anyone can be diagnosed with PMR, but nearly all people with the condition are over 50. The risk for the disease increases with age, so the typical patient is around 70 when PMR strikes. The disease is most common in Caucasians, especially those with Northern European ancestry.
PMR usually begins over just a few days. Many patients assume they must have strained a muscle or injured a joint. Despite the rapid onset and considerable distress, the typical patient is ill for over a month before he's diagnosed.
The two most common symptoms are pain and stiffness. These are usually in the shoulders, with the hips and neck close behind. The shoulder and hip discomfort is almost always equal on both sides of the body. Stiffness is at its worst in the early morning, and it usually takes 45 to 60 minutes for patients to loosen up.
Even though the stiffness wears off as the day wears on, the pain does not. In fact, the pain usually increases with physical activity. In severe cases of PMR, pain and stiffness may prevent a man from getting out of a bed or chair without help. Activities that require raising the arms above shoulder height are particularly challenging.
On its own, PMR does not produce muscle weakness or restrict joint motion. But if PMR goes untreated, patients are likely to limit their activity due to pain and stiffness. This can lead to muscle weakness and stiff joints.
Without treatment, most patients develop fatigue. Many lose their appetites, so weight loss is common. The combination of weakness and weight loss can trigger depression. In addition, many people with PMR complain of fever. The fever is usually low grade. But it can sometimes be quite high if a patient also has GCA.
Doctors usually think of other illnesses before they make the right diagnosis. Fever, weight loss, anemia and weakness may lead doctors to think of cancer or a serious infection. Severe stiffness may mimic Parkinson's disease.
More often, though, joint pain may have doctors considering osteoarthritis or inflammatory diseases such as rheumatoid arthritis. Neck pain can be severe enough to mimic a pinched nerve. And shoulder pain may suggest rotator cuff problems.
Even though many other conditions can mimic PMR, it’s usually not difficult to diagnose — providing a doctor thinks of it.
You can help by knowing these factors that make PMR likely:
- Age over 50, particularly over 65
- Morning stiffness that lasts for at least 30 minutes
- Pain in your shoulders that is usually equally severe on both sides
- Hip and neck pain
- Symptoms that peak within two weeks of when they started and persist for at least two months (unless treated)
- No evidence of cancer, infection or inflammatory joint disease, such as rheumatoid arthritis
Doctors don't have a specific laboratory test for PMR. But they do have several tests that can support the diagnosis. The most important are two blood tests that measure inflammation:
- Erythrocyte sedimentation rate (ESR)
- C-reactive protein (CRP) tests
Most patients with PMR have ESR rates above 40 millimeters/hour. Their CRPs are usually above 6 milligrams/liter. Most PMR patients have anemia, which is usually mild to moderate.
Imaging tests such as ultrasounds and MRIs often show inflammation in areas of pain, but most patients don't need these studies.
With so many nonspecific laboratory findings, perhaps the most defining feature of PMR is its prompt and dramatic response to treatment.
PMR does not respond to the medications that relieve most joint and muscle pain. So acetaminophen (Tylenol and many other brands) and non-steroidal anti-inflammatory drugs (aspirin, ibuprofen and naproxen) don't help. But steroids, such as prednisone, make a dramatic difference.
PMR improves with doses of 15 milligrams to 20 milligrams a day. A typical regimen starts with 15 milligrams once each morning; most patients feel much better in just 2 or 3 days. It's best to reduce the dosage slowly, perhaps by 1 milligram of prednisone a month. Most patients do very well. But before starting PMR-dose steroids, doctors should ask a crucial question: Does my patient also have GCA? The answer is critical for giving the right dose of medicine.
What is GCA?
Giant cell arthritis is also called temporal arteritis. It's a serious type of blood vessel inflammation that usually strikes the arteries of the head and neck, especially in the temples.
Symptoms of GCA
The symptoms of GCA usually begin gradually. The most important is headache, which often centers over the temples. Other, less common symptoms include jaw pain when chewing, tongue pain, and dental or sinus discomfort. But the most feared symptom is vision loss. Because of the threat of blindness, doctors consider GCA a medical emergency.
Most patients with GCA have high ESR and CRP readings and anemia. But unlike PMR, GCA has other specific symptoms.
When doctors examine patients with GCA, they may find thickened, tender or pulseless arteries in the temples. If these are present and the patient also has a high ESR or CRP and a typical set of symptoms he needs immediate therapy.
An ultrasound of the temporal arteries may show abnormalities. But the best test is a biopsy of one or both temporal arteries. A biopsy is done under local anesthesia.
Steroid therapy is very effective for reducing inflammation. Steroids also prevent visual loss. Prednisone is the usual drug of choice. It's the same medication used for PMR. But there are two important differences in the way the drug is used to treat the two diseases.
First, treatment for GCA should be started as soon as possible. With PMR, doctors don’t have to rush.
Second, PMR responds well to low doses of prednisone (about 15 milligrams a day). GCA requires 3 or 4 times that dose. This is likely to increase the risk of side effects. But when vision hangs in the balance, it's a risk worth taking. In general, GCA patients continue to take high-dose prednisone for 2 to 4 weeks. Then they begin to slowly reduce the dose over the next 6 months to 2 years, providing the disease remains well controlled.
We need more research to uncover the causes of GCA and PMR — and to develop better diagnostic tests. New treatments will also be welcome. But for now, steroids can preserve vision for a patients with GCA and restore comfort and function for patients with PMR. That makes six little initials worth a man's attention.
Harvey B. Simon, M.D., is an Associate Professor of Medicine at Harvard Medical School and a member of the Health Sciences Technology Faculty at Massachusetts Institute of Technology. He is the founding editor of the Harvard Men's Health Watch newsletter and author of six consumer health books, including The Harvard Medical School Guide to Men's Health (Simon and Schuster, 2002) and The No Sweat Exercise Plan, Lose Weight, Get Healthy and Live Longer (McGraw-Hill, 2006). Dr. Simon practices at the Massachusetts General Hospital; he received the London Prize for Excellence in Teaching from Harvard and MIT.