Giant cell arteritis, also known as temporal arteritis, is a type of vasculitis, or inflammation of the blood vessels. It primarily affects the arteries in the head, neck, and scalp, and can lead to damage and narrowing of these blood vessels.

The exact cause of giant cell arteritis is not known, but it is thought to be related to a problem with the immune system. The condition is most common in people over 50 years of age and is more common in women than in men.

Symptoms of giant cell arteritis may include headache, scalp tenderness, jaw pain with chewing, vision loss, double vision, or fever. If left untreated, the condition can lead to serious complications, such as stroke or blindness.

The diagnosis of giant cell arteritis usually involves a physical exam, blood tests, and a biopsy of the affected blood vessel. Treatment for giant cell arteritis typically involves high-dose corticosteroids to reduce inflammation and prevent further damage to the blood vessels.

The prognosis for giant cell arteritis varies depending on the severity of the condition and the individual's response to treatment. Early diagnosis and treatment are important to prevent complications and improve the chances of a good outcome. If you experience any symptoms associated with giant cell arteritis, it is important to seek medical attention right away.

With giant cell arteritis, the lining of arteries becomes inflamed, causing them to swell. This swelling narrows your blood vessels, reducing the amount of blood — and, therefore, oxygen and vital nutrients — that reaches your body's tissues.

Almost any large or medium-sized artery can be affected, but swelling most often occurs in the arteries in the temples. These are just in front of your ears and continue up into your scalp.

What causes these arteries to become inflamed isn't known, but it's thought to involve abnormal attacks on artery walls by the immune system. Certain genes and environmental factors might increase your susceptibility to the condition.

The main treatment for giant cell arteritis consists of high doses of a corticosteroid drug such as prednisone. Because immediate treatment is necessary to prevent vision loss, your doctor is likely to start medication even before confirming the diagnosis with a biopsy.

You'll likely begin to feel better within a few days of beginning treatment. If you have visual loss before starting treatment with corticosteroids, it's unlikely that your vision will improve. However, your unaffected eye might be able to compensate for some of the visual changes.

You may need to continue taking medication for one to two years or longer. After the first month, your doctor might gradually begin to lower the dosage until you reach the lowest dose of corticosteroids needed to control inflammation.

Some symptoms, particularly headaches, may return during this tapering period. This is the point at which many people also develop symptoms of polymyalgia rheumatica. Such flares can usually be treated with slight increases in the corticosteroid dose. Your doctor might also suggest an immune-suppressing drug called methotrexate (Trexall).

Corticosteroids can lead to serious side effects, such as osteoporosis, high blood pressure and muscle weakness. To counter potential side effects, your doctor is likely to monitor your bone density and might prescribe calcium and vitamin D supplements or other medications to help prevent bone loss.

The Food and Drug Administration recently approved tocilizumab (Actemra) to treat giant cell arteritis. It's given as an injection under your skin. Side effects include making you more prone to infections. More research is needed.