Giant Cell Arteritis

Question 1

Epidemiology of GCA

Answer 1

-Peak incidence age 70-80
=Rare below the age of 50
-About 75% of patients are female
-Prevalence varies
=Northern Europeans: 20/100,000
=Southern Europeans: 10/100,000
=African / Asian: 1/100,000

-Form of granulomatous vasculitis of medium to large arteries

Question 2

Pathophysiology of GCA

Answer 2

-Genetic predisposition
=HLA Class II region
=P4HA2- proline hydroxylase
=PLG – Plasminogen
-Inflammatory infiltrate of medium to large sized vessels in head, neck and arms (narrowed lumen)
=TH1 and Th17 cells
=Macrophages and giant cells

Question 3

Clinical presentation of GCA

Answer 3

SYMPTOMS
-New onset headache
=Typically unilateral temporal region, can be bilateral
-Pelvic and shoulder girdle pain and stiffness (PMR)- symmetrical
-Difficulty rising from chair unaided and lifting arms up to comb hair
-Visual disturbance
=Diplopia, Blurring, visual loss (optic nerve ischaemia)
- Jaw claudication (pain over masseter muscles on chewing)
-Systemic symptoms- general malaise, lethargy, depression, low-grade fever, anorexia

SIGNS
-Temporal artery swelling & tenderness
=Occasionally focal tenderness and thickening over temporal artery
=Blood pressure difference between 2 arms/ limb claudication
-Visual field defects or reduced visual activity
-Fundoscopy: cotton-wool patches, small retinal haemorrhages, pallor and oedema of optic disc

Question 4

Diagnosis of GCA

Answer 4

-Typical clinical history
-Raised ESR >50mm/hr & CRP
-Mild anaemia (normochromic normocytic)
-Autoantibodies negative
-Temporal artery biopsy- skip lesions may be present
-Temporal artery ultrasonography
-Response to steroids in 3-4 days

Question 5

Management of GCA

Answer 5

-Prednisolone 40-60mg /day- continued for 4 weeks until symptoms have improved (IV methylprednisolone in evolving visual loss)
=Reduce dose by 10mg/2 weeks until daily prednisolone 20mg
=Then reduce 2.5mg every 2 weeks until 10mg
=When at 10mg, reduce dose by 1mg/month until withdrawn

-Steroid sparing medicines
=Tocilizumab 8mg/ 2-weekly (for patients at high risk of steroid toxicity or relapsing disease)
=Methotrexate, azathioprine
-Osteoporosis prophylaxis= vit D and calcium, oral bisphosphonates if 65+
-Manage vascular risk factors

Question 6

Monitoring during follow up of GCA

Answer 6

-Monitor for recurrence of symptoms
-Check ESR and CRP periodically
-Increase steroid dose if symptoms recur and inflammatory markers rise
-Beware of treating ESR and CRP without symptoms!
- Long-term Immunosuppressive if prednisolone dose consistently greater than 10mg

Question 7

Definite indications for rheumatology referral in GCA context

Answer 7

-Unusual presentation (suggestive symptoms but normal ESR, patient under 50 years)
-Patient fails to respond adequately to corticosteroid therapy (suggests the diagnosis is wrong).
-Symptoms cannot be controlled with less than 10mg prednisolone daily (for consideration of immunosuppressives).

Question 8

Visual disturbance in GCA

Answer 8

-Anterior ischemic optic neuropathy = majority of ocular complications. Occlusion of the posterior ciliary artery (a branch of the ophthalmic artery) → ischaemia of the optic nerve head. Fundoscopy typically shows a swollen pale disc and blurred margins
-May result in temporary visual loss - amaurosis fugax
-Permanent visual loss
-Diplopia may also result from the involvement of any part of the oculomotor system (e.g. cranial nerves)

Question 9

Differentials of GCA

Answer 9

-Other vasculitis: granulomatosis with polyangiitis/ Churg-Strauss syndrome, polyarteritis nodosa
-CTD: SLE, Takayasu’s arteritis (younger age, cranial symptoms absent)
-Cervical spondylosis
-Stroke/ TIA
-Acute angle closure glaucoma
-Cluster headache/ migraine
-Sinus disease and ear problems