Giant cell arteritis, also called temporal arteritis, is a disease in which the medium-sized arteries that supply the eye, scalp and face become inflamed and narrowed. This disease can cause loss of vision, so it is essential that the problem be diagnosed and treated as early as possible. Larger blood vessels, including the aorta and its branches, also may be involved, and can lead to the blood vessel weakening and even rupturing years later.
This disorder develops almost exclusively in people older than age 55 and most commonly affects people in their 70s and 80s. It is relatively rare: among people over the age of 55, it affects an estimated 2 people in 1,000.
The cause of giant cell arteritis is unknown, although there has been speculation that in some people, the body's immune system responds incorrectly to an infection, and begins to attack the lining of blood vessels as it would a foreign invader. There may be a genetic contribution as well as suggested by occasional cases that affect more than one member of the same family. One possibility is that the immune system of certain individuals or family members may be genetically programmed to respond to an infection abnormally, a response that leads to giant cell arteritis.