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 body's 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 patient's 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 patient's red blood cells settle in a test tube. The slower the red blood cells settle, the higher the ESR value (measured in mm/hour), which means inflammation is present. Many conditions can cause an elevated ESR, so this test alone is not proof that a person has polymyalgia rheumatica. Another test that checks the level of C-reactive protein (CRP) in the blood may also be conducted. CRP is produced by the liver in response to an injury or