I am a member of another forum where we had an easy to find section with this sort of information. Some one asked for a non-academic explanation of PMR the other day so I have taken the one from there to repeat here.
The basics of PMR:
Polymyalgia rheumatica is disorder that affects large muscle groups in the body with episodes of pain and stiffness. Polymyalgia rheumatica is generally a disorder of older adults over the age of 50 and affects twice as many women as men. In general, the older a person is, the higher the risk of developing the condition.
The cause of polymyalgia rheumatica is not known, but it may be due to an abnormal response of the immune system. In an autoimmune disorder, the body's immune system mistakes healthy tissues as foreign and potentially dangerous invaders into the body and attacks them. This results in inflammation and may lead to the painful symptoms of polymyalgia rheumatica.
The symptoms of polymyalgia rheumatica usually appear suddenly and are moderate to severe. The hallmark symptoms are pain and stiffness on the neck, hips, and shoulders. About 15 percent of people with polymyalgia rheumatica develop a potentially serious complication called temporal arteritis, which includes additional symptoms. For more details on symptoms, refer to symptoms of polymyalgia rheumatica.
Making a diagnosis of polymyalgia rheumatica begins with taking a thorough medical history, including symptoms, and completing a physical examination. There is no precise test to diagnose polymyalgia rheumatica. Medical tests generally include a variety of blood tests that are nonspecific, but their results may increase the suspicion of a diagnosis of polymyalgia rheumatica. These tests include a complete blood count (CBC), which can reveal anemia, one of the symptoms of polymyalgia rheumatic. They also include an erythrocyte sedimentation rate (ESR), which can reveal an inflammatory process occurring in the body.
Tests are also done to rule out other conditions with similar symptoms, such as rheumatoid arthritis.
It is possible that a diagnosis of polymyalgia rheumatica can be missed or delayed because the disease may appear similar to other conditions or diseases, such as aging, influenza, and fibromyalgia. For more information on misdiagnosis, refer to misdiagnosis of polymyalgia rheumatica.
Polymyalgia rheumatica usually disappears on its own without treatment. However this can take several years. In the meantime treatment can be very effective in relieving symptoms and helping people to live normal, active lives. Treatment varies depending on the severity of symptoms, the presence of complications, a person's age and medical history, and other factors. Treatment can include a combination of medication, regular exercise, and eating a healthy diet.
I will also add the GCA Basics article here:
Also known as temporal arteritis or cranial arteritis, giant cell arteritis is the most common form of vasculitis that occurs in adults. Almost all patients who develop giant cell arteritis are over the age of 50. Temporal arteritis commonly causes headaches, joint pain, facial pain, fever, and difficulties with vision, and sometimes permanent visual loss in one or both eyes. Because the disease is relatively uncommon and because the disease can cause so many different symptoms, the diagnosis of temporal arteritis can be difficult to make. With appropriate therapy, temporal arteritis is an eminently treatable, controllable, and often curable disease. The disease is called temporal arteritis because the temporal arteries, which course along the sides of the head just in front of the ears (to the temples) often become inflamed. The term giant cell arteritis is often used because when one looks at biopsies of inflamed temporal arteries under a microscope, one often sees large or giant cells.
Who gets Giant Cell Arteritis?
Temporal arteritis is a disease of older people. The average age at onset is 72, and almost all people with the disease are over the age of 50. Women are afflicted with the disease 2 to 3 times more commonly than men. The disease can occur in every racial group but is most common in people of Scandinavian descent.
Classic Symptoms of Giant Cell Arteritis
The most common symptoms of temporal arteritis are headache, pain in the shoulders and hips (called polymyalgia rheumatica), pain in the jaw after chewing (called jaw claudication), fever, and blurred vision. Other symptoms can include tenderness of scalp (it hurts to comb the hair), cough, throat pain, tongue pain, weight loss, depression, stroke, or pain in the arms during exercise. Some patients have many of these symptoms; others have only a few. Blindness the most feared complication can develop if the disease is not treated in a timely fashion.
What Causes Giant Cell Arteritis?
We do not know. We do know that aging has something to do with the disease. And we know that the body's immune system attacks and inflames the arteries. But we do not know why the immune system attack occurs when and where it does.