Giant cell arteritis (GCA)

Giant cell arteritis is a vasculitis of large and medium size vessels. Although it can affect arteries in the neck, upper body and arms, it occurs most often in the arteries in the temples. For this reason, giant cell arteritis is sometimes called temporal arteritis or cranial arteritis.

Giant cell arteritis is also known as granulomatous arteritis — a reference to a particular type of inflammation it causes.

Epidemiology & Aetiology

• Adults older than age 50 are at greatest risk of giant cell arteritis.
• Women and caucasians are most commonly affected.
• The exact cause isn't known, but researchers believe that genetic, viral and environmental factors may play roles in the inflammation.

Clinical presentation

Giant cell arteritis frequently causes headaches, jaw pain, and blurred or double vision, but the most serious potential complications are blindness and, less often, stroke. These problems occur when swelling in the arteries impairs blood flow to the eyes or brain.

The onset of the symptoms tends to be gradual and includes low grade fever, fatigue, weakness and weight loss.

• A new headache, mild or severe, occurs in at least two-thirds of patients with the pain tending to be located over the sides of the head in front of the ears but may be frontal or other located.
• Nearly one-half of patients suffer from jaw claudication after chewing.
• Impaired vision is often an early manifestation of the disease.
• Permanent partial or complete loss of vision in one or both eyes has been observed in 15-20 % of patients. It is rare for patients to become completely blind in both eyes.
• Polymyalgia rheumatica, which is characterized by pain in the shoulders and hips, is closely linked to GCA, occurring in about 40-50 % of patients.
  

Investigations

• ESR – elevated in most patients with GCA.
• Temporal artery biopsy

Suggested in all cases of suspected GCA even if the diagnosis may appear "classic".

The biopsy is of low risk, causes very little pain, and often leaves little or no scar.

After the use of a topical numbing medication (the same one used by a dentist), a small part of the temporal artery from under the scalp is removed.

• Other ways to diagnose GCA include: ultrasonography, angiographic examination, CT scanning and MR angiography, high resolution MRI and position emission tomography (PET).

Management

• Although there's no cure for giant cell arteritis, immediate treatment with corticosteroid medications usually relieves symptoms and prevents loss of vision.
• Glucocorticoid treatment should be instituted immediately once the diagnosis of GCA is established.
• Daily dosing is more effective than alternate day dosing. The response usually occurs within two to four weeks after the institution of therapy.
• The diagnosis should be reevaluated in patients who are resistant to adequate steroid therapy.
• Steroid withdrawal can begin once clinical remission has been induced.
• Relapses are seen more frequently in the first year or two of the disease.
• Relapses often necessitate increased dosage or prolonged steroid treatment. Some researchers have suggested that the addition of methotrexate may be steroid-sparing while others have not demonstrated any benefit. However the routine addition of methotrexate to glucocorticoid therapy for GCA is not recommended. The efficacy of other cytotoxic drugs, dapsone, antimalarials, etanercept, and penicillamine has not been studied adequately although they have been reported to be helpful in some case reports.
• The finding of an increased risk of visual loss in patients with GCA and thrombocytosis (increase of the number of platelets in the blood), has led some to suggest the addition of drugs like aspirin for patients with high platelet counts, but there is not a lot of data to prove that this may reduce brain/skull problems.

References:

• “Giant cell arteritis”, mayoclinic.com, http://www.mayoclinic.com/health/giant-cell-arteritis/DS00440
• “Giant Cell Arteritis (Temporal Arteritis)”, Vasculitis Foundation, http://www.vasculitisfoundation.org/giantcellarteritis