Most of us are aware of the importance of rapid treatment of giant cell arteritis (GCA), also known as temporal arteritis because the temporal artery is commonly involved.
However, it can be difficult to diagnose with confidence and, because it typically presents with a common symptom, headache, it is easy to overlook.
In adults, GCA is the most common form of vasculitis, it affects large arteries and it should be considered a systemic disorder because it can affect a number of arteries. Temporal arteritis is the most common manifestation of GCA.
Aetiology and epidemiology
The cause and pathogenesis of temporal arteritis are unknown; however, we know that the immune system is involved.
It is more common in patients over 50 and is uncommon under the age of 55. The highest incidence occurs in 70-80 year olds and women are more likely than men to be affected.
Clinical features
Presentation varies depending on which arterial territory is affected. The symptoms can start suddenly or gradually.
When the temporal artery is affected often the first symptom is headache. This can be significant, may be described as throbbing and often affects the temporal area (or the occipital area if the occipital artery is affected).
The headache is different from any previous headache experienced and the patient may complain of scalp discomfort when they brush their hair.
Jaw pain can be another complaint and may be caused by chewing or talking. It is due to ischaemia of the muscles involved in these movements, known as jaw claudication.
Visual disturbance can also occur and blindness may result. This can present suddenly, affects a small group of patients and the blindness will not usually respond to steroids. However, steroids are still required to protect vision in the remaining eye.
The aorta and its main branches can also be affected and this includes thoracic and abdominal portions leading ultimately to an aneurysm, a late complication. This can happen some years after the initial diagnosis.
Do not forget the systemic symptoms associated with the overlapping condition of polymyalgia rheumatica. These include aches and pains in the shoulders, buttocks and thighs, as well as systemic symptoms such as anorexia, weight loss and tiredness.
Atypical presentations also include neurological disease and tongue pain.
Diagnosis
Examination is often unremarkable but there may be tenderness or thickening of the temporal artery and some affected patients have a fever.
The key to diagnosing this condition is thinking of it in the first place. GCA and polymyalgia rheumatica can cause an elevated ESR and raised inflammatory markers such as plasma viscosity and CRP. A normochromic, normocytic anaemia, thrombocytosis and raised alkaline phosphatase may also be present. The key diagnostic marker of GCA and specifically temporal arteritis, is a temporal artery biopsy.
A temporal artery biopsy is worthwhile to help aid diagnosis and justify the need for long-term steroids. However, a negative temporal artery biopsy does not exclude the diagnosis.
Treatment should not be delayed while waiting for biopsy results. Untreated GCA carries the risk of blindness; however, the longer spent on steroids, the lower may be the diagnostic yield of a temporal artery biopsy. You may want to refer urgently to secondary care.
It is important to remember the overlap with polymyalgia rheumatica. A patient with this should be asked directly about headaches and visual disturbance and told to report them as a matter of urgency in case they have GCA.
Treatment
Steroids are the mainstay of treatment and the dosage varies according to the condition treated. Polymyalgia rheumatica often responds to a starting dosage of 10-20mg prednisolone per day. For GCA, higher dosages, often 40-60mg prednisolone per day, are used in the presenting stages.
Anyone with visual symptoms should be seen urgently on a same-day basis by an ophthalmologist. Because of the need for prolonged exposure to steroids, assessment is needed to guide the withdrawal of steroids and to monitor the patient for side-effects.Osteoporosis prophylaxis, BP monitoring and blood glucose monitoring should be considered.
Steroid therapy might be needed for around two years, there is a risk of relapse if the steroids are reduced too quickly. Steroid-sparing drugs such as methotrexate have been used but steroids remain the gold standard of treatment.
Dr Brown is a GP in Leeds
Management of giant cell arteritis
- Giant cell arteritis and polymyalgia rheumatica can co-exist.
- If giant cell arteritis is suspected, steroids should be started immediately before any investigations.
- You should consider referring all patients with suspected giant cell arteritis to secondary care to confirm the diagnosis and guide treatment.
- A temporal artery biopsy is helpful but may not provide a definitive answer.
- Monitor the patient for steroid morbidity regularly.
- Wean the patient off steroids slowly and carefully.
