Giant cell arteritis (GCA) also known as temporal arteritis is an autoimmune disease. Autoimmune diseases are conditions in which immune cells, that normally help fight infections, are misdirected to attack your own tissues. In the case of GCA, these immune cells are involved in an inflammatory reaction in large arteries of the body, mainly branches of the aorta and often, the aorta itself. The inflammation damages the affected blood vessels. It has been estimated that 228,000 Americans have GCA. At present the exact cause of this condition is unknown.
What is Giant Cell Arteritis?
GCA is a form of vasculitis. Vasculitis is defined as a condition in which blood vessels, particularly arteries, become inflamed. In GCA, the aorta and its branches are usually affected. The inflammation in GCA can cause swelling of the blood vessel wall and narrowing of the blood vessel lumen causing decreased blood supply to the neighboring tissues. The blood vessel may also become thrombosed causing severe ischemia or necrosis of tissues ordinarily supplied by the blood vessel.
How common is Giant Cell Arteritis?
GCA is the most common form of vasculitis in patients over the age of 50 years. Data from population-based studies estimate that 1 in 5,000 people over the age of 50 years are affected by GCA each year. The prevalence of GCA is estimated at 278 per 100,000 people over the age of 50 years.
Who gets Giant Cell Arteritis?
Age, gender and ethnicity are all risk factors for GCA. GCA affects people over the age of 50 years and the risk of GCA increases the older one gets. For reasons that are not clear, GCA is 2 to 3 times more common in women than in men. This condition is most commonly seen in people of Northern European descent and is rare in other ethnic groups like Asians and African Americans.
Is Giant Cell Arteritis different from Polymyalgia Rheumatica?
Yes, GCA is different from polymyalgia rheumatica. Polymyalgia rheumatica is a condition in which people experience severe stiffness and pain in the neck, shoulders and hips. Symptoms are usually worse in the morning and improve later in the day. Blood tests show evidence of inflammation. There is a close association between polymyalgia rheumatica and GCA. While approximately half of all patients with GCA also have symptoms of polymyalgia rheumatica, only 16-21% of patients with polymyalgia rheumatica develop GCA.
Most patients with GCA will have one or more of the symptoms listed below. However, in a minority of patients these symptoms are absent or develop late in the course of the disease making the diagnosis of underlying GCA a challenge.
- New headache, usually in the temples
- Tenderness of the scalp
- Swelling of the arteries near the temples
- Vision changes like a curtain in the field of vision, sudden vision loss (temporary or permanent) or double vision.
- Pain in the muscles of the jaw while chewing food
- Shoulder or hip joint aching and stiffness
- Weight loss
- Poor appetite
- Low grade temperatures
Less common symptoms
- Cramping or aching in the arms with activity
- Audible pulsations (bruits) over the axillary areas
- Cramping or aching in the legs while walking which improves with resting
- Dry cough or sore throat
- Stroke-type symptoms
The diagnosis of GCA is based on identifying one or more of the symptoms or physical findings listed above, laboratory studies with appropriate changes, and temporal artery biopsy findings showing arteritis. Physical examination may show swelling or decreased pulses in the temporal artery (artery that is superficial and supplies the scalp). Occasionally, your doctor may find decreased pulses in the arms or legs suggesting this diagnosis. While there is no blood test for diagnosing GCA, laboratory tests show evidence of inflammation. Your doctor may check a sedimentation rate and C-reactive protein, two blood tests that are usually high in patients with GCA. The gold standard to confirm the diagnosis of this condition is biopsy of the temporal artery. In most cases of GCA, this artery will show evidence of inflammation. In some cases, if this diagnosis is suspected, imaging of the arteries in the body with CT scan or MRI may be helpful.
GCA is a treatable condition. All patients are started on prednisone (or other corticosteroid) which helps decrease inflammation. Addition of aspirin may be beneficial. Your doctor will follow blood tests with markers of inflammation every few months while the prednisone dose is gradually decreased. Most people require about 1 to 2 years of treatment. In some cases, longer courses of prednisone are needed. Occasionally, other medications to target the immune system may be added.
What are the complications of Giant Cell Arteritis?
The most common severe complication of GCA is blindness. This happens because of inflammation and blockage of the blood vessels that supply the main nerve of the eyes. Other complications include formation of aneurysms (widening or ballooning of the aorta). Rarely, people can develop inflammation in the vessels supplying the arms or brain.
Overall, the prognosis of GCA, if treated promptly, is good. However, blindness can occur in up to a fifth of cases and may be irreversible. The risk of blindness after starting treatment is very low. GCA is usually controlled with treatment but prolonged treatment with prednisone or addition of other immune suppressing medications may be required. People with GCA have a normal life expectancy, unless the disease causes an aortic aneurysm, which can occasionally rupture (tear).
What’s new in Giant Cell Arteritis?
At present, prednisone remains the standard of care for GCA. While it works very well, there are many side-effects of this medication. Other immune suppressing medications have been tried but do not work very well for this condition. Methotrexate, a medication commonly used for treatment of rheumatoid arthritis, is sometimes used to help reduce the risk of disease flares. Other treatments are currently being investigated. The types of inflammatory cells that are involved in the arteritis are being identified in current research. Understanding the nature of the inflammatory processes may lead to improved treatment.
Revision: September 2012