Giant cell arteritis

GIANT CELL ARTERITIS (GCA) is the commonest systemic vasculitis. Inflammation affects the extracranial branches of the carotid artery in patients older than 50 years of age. The aetiology is unknown but granuolomatous inflammation is seen on arterial biopsy. The most recognisable presentation is that affecting the temporal arteries with visual loss being a feared complication. The ultimate concern is of irreversible visual loss in a treatable condition, so giant cell arteritis is regarded as a true medical emergency.

Each year the MDDUS receives complaints and claims of clinical negligence in relation to the delayed or missed diagnosis of GCA. As with many conditions there is not one definitive sign or test upon which to irrevocably base the diagnosis but a careful history and clinical assessment coupled with an awareness of the atypical manifestations of this condition may prevent mistakes.

Epidemiology

GCA is very rare before the age of 50, with the mean age of onset in the seventh decade. It is at least twice as common in females and is commoner in northern climates and Caucasians.

Symptoms

The patient complains of an abrupt onset of headache which is often unilateral but not always. Around 75 per cent of individuals will complain of headache which may be found in a new position and is of different or unusual character. The quality of the pain has been described as boring and of moderate severity compared to a simple headache. The pain is commonly felt in the temple but also rarely in the occiput if the occipital artery is involved. Associated scalp tenderness and jaw or tongue claudication are common features and show the highest positive predictive value for a positive temporal artery biopsy.

Almost all patients with GCA will experience at least one systemic feature, such as weight loss, fever, anaemia, fatigue and depression. As there is a close association with polymyalgia rheumatica, proximal limb girdle pain and stiffness may also be prevalent.

Visual symptoms are seen in around a quarter of presentations. The most frequent being aumorosis fugax, unilateral visual loss, double vision and blurred vision. Visual loss is the most worrying complication and can occur in up to a fifth of cases. If one eye is affected then the chances of a second eye being involved can be between 20-50 per cent. Therefore a high index of suspicion is needed and a judicious use of treatment as this is a preventable cause of visual loss.

Signs

Clinically the patient may seem unwell and have scalp tenderness as well as a palpable beaded or tortuous temporal artery. The temporal arteries may lose pulsation and visual field loss may be demonstrable. Fundoscopy may reveal a pale or swollen optic disc or retinal artery occlusion. A swinging afferent papillary defect can also occur.

Investigation

An elevated ESR greater than 50 is one American Society of Rheumatology classification criterion (see box), but it should be noted that lower ESRs can occasionally occur. Temporal artery biopsy is thought to be the most sensitive test and does have a high negative predictive value. However, the lesions are not confluent and if GCA is still strongly clinically suspected after a first negative biopsy a second may be performed.

Treatment

This is a common treatable cause of blindness. If there is a strong clinical suspicion of GCA, immediate treatment with glucocorticoids is indicated. Many laboratories will do an urgent ESR which will be available the same day, which may help to confirm clinical suspicions. If ESR is normal the glucocorticoid prescription can be reviewed. An urgent referral to a specialist centre with the aim of performing a temporal artery biopsy within the first week is advised. Local services vary and it is important to be aware of the relevant receiving specialty as it can be either ophthalmology, rheumatology or vascular surgery. Temporal artery biopsy is important because a positive result will have prognostic implications and confirms the need for long-term glucocorticoid therapy.

If it is uncomplicated GCA (no visual change or jaw claudication), 40-60 mg of prednisolone per day is advised until symptoms resolve and inflammatory markers decline. If there is evidence of evolving visual loss, an in-patient assessment may be required and i.v. methyl prednisolone is recommended for three days. If there is established unilateral visual loss, 60mg once daily of prednisolone should be prescribed to protect the other eye.

At initial presentation inflammatory markers and chest X-ray (if possible) should be performed. The CXR is to assess if there is involvement of the thoracic aorta. Consideration should also be given to starting aspirin (some evidence to support reduction in visual loss), as well as calcium, vitamin D and bisphosphonate and gastroprotection, particularly in those over 65 years of age.

A suggested steroid tapering regimen is 40-60mg prednisolone continued for four weeks (until resolution of symptoms and laboratory abnormalities), then dose reduced by 10mg every two weeks to 20mg, then by 2.5mg every two to four weeks to 10mg, then by 1mg every one to two months provided there is no relapse.

Recording the ESR within the case records and ensuring that the symptoms do resolve on glucocorticoids treatment is vital. As always it is recommended that the clinician keeps good legible notes of the consultation and these will be essential should any subsequent medico-legal issues arise. A relapse is considered if there is a rise in ESR to greater or equal to 40 and recurrence of symptoms. Most patients will require glucocorticoids for two to three years and should have their ESR monitored throughout this time.

Conclusion

As with many clinical emergencies it is often the initial clinical assessment of GCA that is the most important factor in determining the long-term outcome. As detailed above there are a number of pitfalls in the diagnosis, particularly in the atypical presentations. However, an awareness of the condition and current guidelines outlined, coupled with a careful history and examination makes falling into these pitfalls much less likely. In short, the prompt diagnosis of giant cell arteritis and appropriate action will in a good proportion of presentations of this condition save sight.

Dr Rajan Madhok is a consultant physician and rheumatologist at the Centre for Rheumatic Diseases at the Glasgow Royal Infirmary

Dr Nicola Alcorn is a physician at the Centre for Rheumatic Diseases at the Glasgow Royal Infirmary

CLASSIFICATION

The American College of Rheumatology (ACR) classification criteria for GCA

• Age at disease onset >50 years: development of symptoms or findings beginning at the age of >50 years

• New headache: new onset of or new type of localised pain in the head

• Temporal artery abnormality: temporal artery tenderness to palpation or decreased pulsation, unrelated to arteriosclerosis of cervical arteries

• Elevated ESR: ESR>50 mm/h by the Westergren method

• Abnormal artery biopsy: biopsy specimen with artery showing vasculitis characterised by a predominance of mononuclear cell infiltration or granulomatous inflammation, usually with multinucleated giant cells

Patients require three out of these five criteria to fulfil a diagnosis of GCA by these guidelines