Giant cell arteritis (GCA), also known as temporal arteritis, is a type of vasculitis or arteritis, a group of diseases whose typical feature is inflammation of blood vessels. In the case of GCA, the vessels most commonly involved are the arteries of the scalp and head, especially the arteries over the temples.
GCA may overlap with another disease, polymyalgia rheumatica (PMR). 5 to 10% of patients with PMR will at some point be diagnosed with GCA. Looked at the other way, about one-half of patients with GCA will have symptoms of PMR. The two conditions can occur together or separately, with one following the other. GCA affects the same patients as PMR – only older adults (usually over 60), females more than males, and whites much more than nonwhites. Like PMR, the cause of GCA is unknown.
Symptoms of giant cell arteritis may include:
There is no specific blood test or other noninvasive way to confirm the diagnosis of GCA. The sedimentation rate (“sed rate”) and C reactive protein (CRP) – tests for inflammation – ordinarily are significantly elevated, but because other diseases can cause high sedimentation rates, these findings cannot be relied on for proof of the diagnosis of GCA.
To prove the diagnosis of GCA, it is traditionally necessary to take a small piece of the temporal artery by biopsy and then examine the wall of the artery under the microscope for evidence of inflammation. The temporal artery biopsy is an outpatient procedure, done under local anesthesia, and leaves only a small scar at the hairline in front of the ear that generally cannot be seen.
A new technique for diagnosing GCA is available at Brigham and Women’s Hospital, and involves the use of ultrasound. The advantage of this technique is that it is noninvasive, allows for examination of multiple arteries, and provides immediate results.
Treatment for GCA must begin as soon as possible. If the diagnosis is strongly suspected, treatment will be started before the diagnosis can be proved or disproved. Unlike the treatment for PMR, which requires only low dose steroids (or “glucocorticoids”), higher doses of steroids are needed for the treatment of GCA, typically 40-60 mg of Prednisone per day. Headaches and other symptoms subside quickly, and the sedimentation rate and C reactive protein decline to normal range.
The high dose of steroids is usually kept up for 1 month and then slowly tapered. The speed of the taper will be adjusted if there are recurring symptoms or significant rises in the sed rate or CRP, but in most cases the Prednisone dose can be reduced to about 5-10 mg per day over several months, and can eventually be discontinued entirely. Later recurrences of GCA are rare.
If there is no loss of vision when the diagnosis of GCA is made, and if treatment is promptly started with daily, high-dose Prednisone, the risk of subsequent visual loss is very small.
With higher doses of steroids side-effects are more common, and must be attentively monitored by the physician. To protect against bone loss, supplements of calcium and vitamin D are recommended, and are often supplemented with bisphosphonate medications (alendronate, Reclast, and others). Some of the side effects from high dose steroids – for example, jitteriness and weight gain – can be unpleasant, but they are reversible, and subside as the steroid doses are reduced to lower levels.
A newer treatment for GCA is tocilizumab (Actemra), which is administered either by self-injection or by intravenous infusion. If side-effects from Prednisone occur or are anticipated, the addition of tocilizumab can help to accelerate the taper of steroids. Tocilizumab is a biologic agent, and can have its own side-effects, including an increased risk of infection.
The diagnosis of GCA is a matter of urgency, because of the risk of sight loss. Expedited evaluation for the diagnosis of GCA, which includes consultation by a rheumatologist and an ultrasound of the temporal alterities, can be obtained through the Brigham and Women’s Fast Track Clinic for the Diagnosis of Giant Cell Arteritis.
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