Polymyalgia rheumatica (PMR) is a disease or medical syndrome most commonly characterized by widespread pain and stiffness in muscle groups in different areas of the body, such as the hips, shoulders, and neck. The disease is rare, and physicians are, for the most part, at a loss in terms of definitively identifying polymyalgia rheumatica causes. Based on the nature of the condition as a rheumatic disease, some researchers are able to hypothesize that possible polymyalgia rheumatica causes may be related to some sort of defect in the patient's immune system. Other studies, though inconclusive, hypothesize that there may be a correlation between a person's genetic makeup and his or her likelihood to acquire the disease. Further studies research the possible link between viruses as primary polymyalgia rheumatica causes or triggers.
The inflammation and pain present in polymyalgia rheumatica are the result of the body's immune system effectively attacking itself, usually centered around specific joints in the body. White blood cells and other proteins that would normally attack foreign agents start attacking the area around the joint, causing inflammation, stiffness, and pain in the muscle around that area. Polymyalgia rheumatica is classified as a rheumatic disease because these attacks and inflammation occur for no apparent reason, as there is no apparent threat to the body in any of the affected areas. The condition may be rooted primarily in a defect in the immune system, especially considering giant cell arteritis, a disease similar to polymyalgia rheumatica that is often classified as an autoimmune disease as well.
Some researchers have tentatively concluded that, among other factors, polymyalgia rheumatica tends to be more common in Caucasian people, or more specifically, those of Northern European ancestry. The disease also tends to be more common in women than in men. In addition to other considerations, such as certain patterns in family histories of the disease and other genetic factors, some researchers have been led to believe that genetics are among the list of possible polymyalgia rheumatica causes. Although correlation does not imply causation, these studies may at least indicate that certain individuals may be more likely to develop the disease than others.
Still other studies look for outside triggers to the disease, despite the apparent arbitrariness of the immune system attacks. These studies, though inconclusive, observe that the disease tended to have its onset in cycles throughout a population, similar with the natural contagious process of viruses. In particular, some viruses that have been identified as possible polymyalgia rheumatica causes are the B19 virus, the adenovirus, and human parainfluenza viruses (HPIVs). Some researchers hypothesize that the disease may be caused by a combination of all of these factors, genetic and environmental.