Rheumatoid arthritis affects joints and other systems in the body. Dryness of the eyes and mucous membranes are referred to as Sjogren's Syndrome. The heart is usually spared but the lungs can be affected by pleurisy, scarring, and the formation of nodules in the lungs. The nervous system may be involved by compression neuropathy (e.g. carpal tunnel syndrome), peripheral neuropathy, or occasionally from cervical cord compression. The rare complication of vasculitis (inflammation of blood vessels) may be devastating because of gangrene or severe internal organ damage. Some of the effects of rheumatoid arthritis may be "invisible" such as anemia or abnormalities in the white blood cell count. Osteoporosis is usually asymptomatic until a fracture occurs.