Giant cell arteritis (GCA) is a common inflammation disease of medium- to large-sized arteries. These arteries can become narrowed, restricting blood flow to affected parts of the body. Giant cells are immune cells found in high concentrations inside affected arteries.
Arteries in the head are the most commonly affected, but arteries in the chest, neck, heart, and other parts of the body may also be involved. When the arteries in the temples of the head are affected, it is termed temporal arteritis or cranial arteritis.
There are 3 patterns seen in giant cell arteritis:
- primarily affecting the head
- primarily affecting the larger vessels of the chest and neck
- a wasting, generalized disease
GCA is unusual in people under 50 years of age. Two-thirds of people who have giant cell arteritis are women . People of African descent are less commonly affected.
GCA is closely associated with a disease called polymyalgia rheumatica (PMR), which many experts believe is a different manifestation of the same underlying disorder. 10% to 20% of people with PMR develop GCA.
More than 50% of people with GCA also have the symptoms of PMR. Fortunately, the same treatment is effective for both conditions, but GCA requires much higher doses.
GCA is an autoimmune disease in which the body's immune system mistakenly attacks the person's own tissue. Autoimmune diseases in general are poorly understood. They tend to run in families, but not so much that we can say they're inherited or genetic diseases. Many doctors believe it takes a combination of predisposing genes and environmental factors to trigger the condition.
Symptoms and Complications
Early symptoms of GCA include fever, weakness, and weight loss, which may come on suddenly. These symptoms may go on to the classic symptoms of GCA, such as:
- double vision or blurred vision, or a black curtain coming over vision; these symptoms are due to narrowing of the main artery to the eye
- headache in the temple or back of the head (60% of people have this symptom)
- sensitive, tender scalp
- swollen, bumpy, tender arteries in the temple, often lacking a noticeable pulse
- weak or painful jaw muscles - lack of oxygen to jaw muscles causes chewing brings on pain that goes away when stopped
- weight loss
- anemia and other blood abnormalities
If arteritis is left untreated, it can progress to the following symptoms:
- blind spots or sudden blindness in one eye
- heart attack
- other serious conditions due to impaired blood flow in the arteries
Blindness is a serious threat in arteritis. In a few cases, vision loss is the first sign of GCA. Unfortunately, any damage already done is usually irreversible. Most people get warning symptoms (called prodromes), such as fluctuating vision, black curtains that briefly descend over vision in one eye (called amaurosis fugax), and headaches, giving them time to take action and see their doctor.
At least 50 % of GCA patients also have polymyalgia rheumatica (PMR). About 10% to 20% of people with PMR go on to develop GCA. Arteritis may appear before, during, or after the onset of PMR. The primary symptoms of PMR are severe stiffness and pain in the neck, shoulder, and hip muscles. There may also be fatigue, joint pain, and anemia.
Making the Diagnosis
GCA is diagnosed by a thorough physical examination, blood tests, and sometimes by taking a biopsy (tissue sample) of the affected temporal arteries. Two tests, the erythrocyte sedimentation rate (ESR) and C-reactive protein, are usually elevated in GCA. The ESR measures how fast erythrocytes (red blood cells) settle to the bottom of a thin test tube.
It may be necessary to do tests that take images of the blood vessels in the chest and neck and to check for signs of heart damage. GCA can damage the aorta (the largest artery in the body, which originates in the heart) and other major vessels. Tests such as ultrasound, MRA and PET scans of the temporal artery can take images in a non-invasive manner . Sometimes, an angiogram needs to be done.
If a biopsy is needed, usually a couple of centimetres are removed fro