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What is Polymyalgia rheumatica and explain in detail?
Polymyalgia rheumatica (PMR) is a syndrome experienced as pain or stiffness, usually in the neck, shoulders, upper arms, and hips, but which may occur all over the body. The pain can be sudden, or can occur gradually over a period. Most people with PMR wake up in the morning with pain in their muscles; however, cases have occurred in which the person has developed the pain during the evenings or has pain and stiffness all day long.People who have polymyalgia rheumatica may also have temporal arteritis (giant cell arteritis), an inflammation of blood vessels in the face which can cause blindness if not treated quickly. The pain and stiffness can result in a lowered quality of life, and can lead to depression. It is thought to be brought on by a viral or bacterial illness or trauma of some kind, but genetics play a role as well. Persons of Northern European descent are at greater risk. There is no definitive laboratory test, but C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) can be useful.
PMR is usually treated with corticosteroids taken by mouth. Most people need to continue the corticosteroid treatment for two to three years. PMR sometimes goes away on its own in a year or two, but medications and self-care measures can improve the rate of recovery.PMR was first established as a distinct disease in 1966 by a case report on 11 patients at Mount Sinai Hospital in New York, NY. It takes its name from the Greek word Πολυμυαλγία polymyalgia, which means "pain in many muscles".

Signs and symptoms
A wide range of symptoms can indicate if a person has polymyalgia rheumatica. The classic symptoms include:
Pain and stiffness (moderate to severe) in the neck, shoulders, upper arms, thighs, and hips, which inhibits activity, especially in the morning/after sleeping. Pain can also occur in the groin area and in the buttocks. The pain can be limited to one of these areas as well.  It is a disease of the "girdles" meaning shoulder girdle or pelvic girdle.
Fatigue and lack of appetite (possibly leading to weight loss)
Anemia
An overall feeling of illness or flu-like symptoms.
Low-grade (mild) fever or abnormal temperature is sometimes present.
In most people, it is characterized by constant fatigue, weakness and sometimes exhaustion.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 headaches, scalp tenderness, jaw or facial soreness, distorted vision, or aching in the limbs caused by decreased blood flow, and fatigue.

Causes
The cause of PMR is not well understood. The pain and stiffness result from the activity of inflammatory cells and proteins that are normally a part of the bodys disease-fighting immune system, and the inflammatory activity seems to be concentrated in tissues surrounding the affected joints. During this disorder, the white blood cells in the body attack the lining of the joints, causing inflammation. Inherited factors also play a role in the probability that an individual will develop PMR. Several theories have included viral stimulation of the immune system in genetically susceptible individuals.Infectious diseases may be a contributing factor. This would be expected with sudden onset of symptoms, for example. In addition, new cases often appear in cycles in the general population, implying a viral connection. Studies are inconclusive, but several somewhat common viruses were identified as possible triggers for PMR. The viruses thought to be involved include the adenovirus, which causes respiratory infections; the human parvovirus B19, an infection that affects children; and the human parainfluenza virus. Some patients attribute the onset of PMR to stress.Persons having the HLA-DR4 type of human leucocyte antigen appear to have a higher risk of PMR.

Diagnosis
No specific test exists to diagnose polymyalgia rheumatica; many other diseases can cause inflammation and pain in muscles, but a few tests 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. A patients answers to questions, a general physical exam, and the results of tests can help a doctor determine the cause of pain and stiffness.One blood test usually performed is the erythrocyte sedimentation rate (ESR) which measures how fast the patients red blood cells settle in a test tube