The vasculitides are a heterogenous group of disorders caused by vascular inflammation. As the vessel wall dies, ischaemia and infarction occur distal to the area of necrosis. The easiest system for classifying this group of conditions is therefore by vessel size, which aids in prediction of outcome and/or complications. The small vessel vasculitides are further subdivided according to their association with antineutrophil cytoplasmic antibodies (ANCAs).

The vasculitides can occur as idiopathic or secondary phenomena (e.g. complicating rheumatoid arthritis or systemic lupus erythemato-sis). In clinical practice, the most common vasculitis is giant cell (temporal) arteritis. The medium-and small-vessel vasculitides will be covered in the next chapter.

Giant cell (temporal) arteritis

Giant cell arteritis (GCA) is a granulomatous inflammation of the aorta and large vessels, with a predilection for the extracranial branches of the carotid artery. The characteristic presentation is of rapid onset (1–2 days) of temporal headache, scalp tenderness and jaw claudication. GCA affects both sexes equally and usually only occurs in those over 60 years of age. Although it is relatively uncommon, with only 42 cases per million over 60 years of age, the diagnosis is frequently considered, as headache is a common presenting complaint.

The most feared complication is of visual disturbance. Irreversible blindness occurs when the arteries supplying the retina or optic nerve head become involved (central retinal and posterior ciliary arteries); diplopia and ptosis may also occur. Visual loss may be the first symptom of GCA.

In addition, 50% patients have a history of polymyalgia rheumatica (PMR) – an inflammatory disease causing classic shoulder and girdle muscular pain and stiffness, in the absence of weakness (which differentiates it from an inflammatory muscle disease).

The ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein) are generally elevated, although disease in the presence of normal inflammatory markers has been reported. Temporal artery biopsy is notoriously unreliable due to the presence of skip lesions – areas of normal-looking tissue interspersed between areas of granulomatous inflammation – but if positive is diagnostic.

Treatment

Treatment for both GCA and PMR is corticosteroid therapy. As GCA can cause acute visual loss, steroids should be commenced before a temporal artery biopsy is performed; the abnormal histological features persist for up to 3 weeks after the commencement of steroid therapy and treatment delay may have devastating consequences. GCA requires high-dose steroids (1mg/kg oral prednisolone/day up to a maximum of 60mg, consider i.v. bolus in the presence of visual symptoms), whereas PMR responds to much lower doses (e.g. 15 mg prednisolone/day). The clinical response is dramatic and steroids can be tapered according to the decline in symptoms and inflammatory markers. However, the majority of patients take 2 years or more to stop steroid therapy, so bone protection is mandatory and the use of azathioprine or methotrexate as steroid-sparing agents should be considered. Relapse rates vary from 30–80%.

Takayasu arteritis

This rare vasculitis is commonest in women under 50 years of age from the Far East, Central and South America and India. The UK incidence is only 0.1 per million/year. It is known as the ‘pulseless disease’ as large branches of the aorta become successively occluded. Symptoms are principally those of chronic vascular ischaemia: claudication, visual disturbances and strokes, although many experience systemic upset and arthralgia. On clinical examination, absent pulses and bruits are common, and a record of affected arterial territories is helpful in monitoring disease progression.

Diagnosis is by arteriography, which reveals vessel narrowing or post-stenotic dilatation and magnetic resonance ateriography (MRA) reveals vessel wall oedema. Treatment requires corticosteroids and immunosuppression. Five-to-ten year survival rates are now 80–90% but approximately half will experience permanent disability.