Giant Cell Arteritis

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Learning objectives

  • What is Giant Cell arteritis and why important
  • What are the typical signs and symptoms
  • Appropriate investigations
  • Managing the patient with Giant Cell arteritis

Introduction

  • This is a rare cause of vasculitis of medium sized arteries.
  • It can affect the aorta and aortic arch branches.
  • It can cause an anterior ischaemic optic neuropathy
  • It may be rapidly bilateral and can lead to blindness.
  • Early diagnosis and treatment is vital to preserve vision
  • GCA affects both sexes but is commoner in females.

Aetiology

  • Inflammation of small and mid-sized arteries and occasionally aorta
  • Usually the external branches of the carotid artery with vascular narrowing.
  • Superficial temporal arteries and posterior ciliary branch of the ophthalmic artery.
  • Possibly an immune attack on the internal elastic lamina of the vessel wall.
  • Likely a Th1 antigen-driven inflammatory process.
  • Varicella zoster virus has been found in biopsies.
  • The adventitial layer appears the most affected but biopsies show transmural inflammation.
  • Involvement of the internal carotid artery and its branches is uncommon.

Clinical

  • Polymyalgia rheumatic: fever, weight loss, proximal pain and stiffness syndrome involving shoulder neck and pelvis.
  • Jaw and even tongue claudication (necrosis is rare) precipitated when chewing.
  • A new dull persistent headache and temporal arterial tenderness
  • Transient or permanent monocular visual loss and even ptosis and diplopia
  • There may be thickened nodular temporal arteries with tenderness. There are exceptional presentations with a stroke which may be anterior or posterior circulation.
  • Strokes, however, may simply be coincidental and are not uncommon in this age group.
  • Increased risk of myocardial infarction and stroke and thoracic aortic aneurysm formation.
  • Fundoscopy in an affected eye with an anterior ischaemic optic neuropathy due to GCA is often less clear as it is the ciliary artery and not the central retinal artery that is affected.

Differential

  • Atherosclerotic disease
  • Takayasu's disease


Investigations

  • FBCnon-specific normocytic normochromic anaemia with thrombocytosis.
  • ESR and CRP The ESR is usually markedly elevated at over 100 mm/hr and should at least be over 50 for the diagnosis. The CRP should also be elevated.
  • ALP There is often an elevated ALP is also seen in about 30%
  • Temporal artery ultrasound: may show distinctive thickening and a halo appearance due to swelling and oedema in the vessel wall. A halo is seen in about 70% of those who are biopsy positive. The halo usually disappears with treatment.
  • Temporal artery biopsy (TAB): needed within days of starting steroids. The key finding is the presence of giant cells and inflammation of the vessels. The pathology is patchy with skip lesions so a negative biopsy may mean failure to biopsy affected segments of the vessel. Usually the affected side is biopsied and some biopsy both sides.
  • PET scanning: scan show the involvement of the aorta and other large vessels but not the STA as it is too small. It is not a routine test outside tertiary centres.
  • MRI: some different modalities are being explored as an alternative to biopsy

Diagnostic criteria

American College of Rheumatology criteria for GCA
1.Age 50 years or older
2.New-onset localised headache
3.Temporal artery tenderness or decreased temporal artery pulse
4.Temporal artery biopsy characterised by mononuclear infiltration or granulomatous inflammation
5.ESR > 50 mm/h
Three of the above five criteria were required to diagnose GCA

The Sensitivity of the ACR criteria ARE 93.5% and a reported specificity of 91.2% for the classification of giant-cell arteritis compared with other vasculitides.

Management

Management of suspected GCA is normally High-dose steroids started immediately to avoid potential visual loss - Prednisolone 1 mg/kg usually is given and usually results in a dramatic reduction of other symptoms too. If the symptoms only suggest PMR (no headache, no visual symptoms, no temporal artery tenderness and only systemic symptoms and proximal pain syndrome) then a lower dose of Prednisolone 15 mg is given usually with a dramatic improvement in the proximal pain syndrome.

  • Urgent referral should then be to a physician experienced in managing GCA which may be neurology, geriatric medicine, rheumatology or ophthalmology depending on local practice.
  • A temporal artery biopsy should be done within days, but treatment is often continued when biopsy negative if the other criteria are met. Steroids are reduced slowly over 18-24 months titrated to clinical response and ESR/CRP.
  • Steroid-sparing agents may be used. Other more potent anti-inflammatory treatment may be given if there is suspected cerebral involvement. Start Osteoporotic Bone protection.
  • It is advisable to also consider Aspirin 75 mg od if tolerated as well as good BP and vascular risk factor management.
  • Sadly most patients with GCA experience steroid-related complications. These are not insignificant and particularly in patients of advanced age have associated morbidity and even mortality and include diabetes mellitus, osteoporosis with vertebral compression fractures and Cushing syndrome. Steroid-sparing agents such as methotrexate have not shown equivalence.
  • However newer agents such as Tocilizumab (8 mg/kg) which is an antibody to the IL- 6 receptors can reduce relapses and steroid dosing