Temporal arteritis is a systemic vasculitis that involves large and medium sized vessels. Another name of this disease is giant cell arteritis (GCA) or Horton’s arteritis. It mainly affects the extracranial branches of the carotid arteries in people more than 50 years old. Temporal arteritis will cause permanent visual loss, ischaemic strokes, and thoracic and abdominal aortic aneurysms.
Temporal arteritis treatment consists of high dose prednisone for a prolonged time. Thus, there is the initial, maintenance and reduction regime which is currently controversial. However, the common practice for the initial dose is 40-60 mg of prednisone per day. This regime was known since the 1950s to induce and remain in remission.
After that, a subsequent tapering regime needs to be tried after 1-2 months or no steroid resistance is detected. This is for achieving a maintenance dose of 7.5–10 mg per day or lower. However, doctors need to be careful because relapse is frequent during steroid tapering. One study suggested a starting dose of 30–40 mg per day of prednisone tapering to 10 mg per day within six months and to 5–7.5 mg per day within one year was effective and less toxic than higher dose regimens.
Higher and more prolonged steroid requirements may lead to initial systemic inflammatory response which is characterised by fever, weight loss, erythrocyte sedimentation rate ⩾85 mm/hour, and/or anaemia. Tapering regimen is adjusted according to the symptoms and adverse events. If there is e bent of relapses, temporary increases in steroid doses may be required.
During tapering regime, assessment of symptoms and signs, erythrocyte sedimentation rate, and C-reactive protein level are the most useful data in monitoring the disease. Patients with temporal arteritis are able to stop steroid therapy after two years, however, many studies agreed that even after nine years of steroid, there is still evidence of inflammation in the vessels despite no clinical sign.
A great consequence may happen if there is persistent vascular inflammation including risks of disease relapse and the development of aortic aneurysms as a long term effect. Other treatment modalities are available since steroids are associated with significant treatment-related complications such as fractures, diabetes mellitus, hypertension and sepsis. Steroid need to be started by professionals.
Calcium and vitamin D supplements must be provided to all patients treated with steroids to prevent fractures and Bisphosphonate therapy should be considered in patients with osteoporosis. This is because steroids can cause bone mass loss. Other than that, many patients also experience overt relapses and subclinical disease progression with this single steroid therapy.
Combination therapy of Methotrexate and Prednisone may be useful to control disease activity or to decrease the dose of steroids. In a Spanish trial, this combination therapy can reduce the proportion of patients who experienced relapses and the mean cumulative dose of prednisone which has been proven can cause other complications.
Methotrexate is actually the recommended first-line treatment in the management of rheumatoid arthritis but it is also effective in a wide range of other systemic inflammatory diseases. Hence, Methotrexate is a best candidate to be used in the temporal arteritis even though there has been conflicting evidence of methotrexate’s efficacy in this disease.
Beside of the drugs mentioned above, synthetic immunosuppressants, including azathioprine, leflunomide, mycophenolate mofetil, hydroxychloroquine, dapsone and cyclophosphamide, have also been used in the temporal arteritis. However, the evidence supporting their use is very limited.
The benefit of these drugs has only been mentioned in one small non-randomized double-blind study of azathioprine in patients with systemic vasculitis showed a significant reduction in mean steroid dose over 52 weeks. Hydroxychloroquine also has shown no evidence of efficacy in an abstract of a randomised controlled trial.