GIANT CELL ARTERITIS

Giant cell arteritis

Giant cell arteritis (GCA) is a granulomatous necrotizing arteritis with a 

predilection for large and medium-size arteries, particularly 

Predilection for -Superficial temporal Artery 
                          -Ophthalmic Artery
                          -Posterior ciliary Artery
                          -Proximal vertebral Artery

The severity and extent of involvement are associated with the quantity of elastic tissue in the media and adventitia. Intracranial arteries, which possess little elastic tissue, are usually spared.

1. Presentation is in old age 7th and 8th decade with the following:

• Scalp tenderness, first noticed when combing the hair, is common.
• Headache that may be localized to the frontal, occipital or temporal areas or be more generalized.
• Jaw claudication (pain on speaking and chewing) caused by ischaemia of the masseter muscles is virtually pathognomonic.
• Polymyalgia rheumatica is characterized by pain and stiffness in proximal muscle groups (typically the shoulders).
• The symptoms are usually worse in the morning and after exertion, and may precede cranial symptoms by many months.
• Non-specific symptoms such as neck pain, weight loss, fever, night sweats, malaise and depression are common.
• Blindness of sudden onset with minimal systemic upset (occult arteritis) is uncommon.

2. Other features

• Superficial temporal arteritis is characterized by thickened, tender, inflamed and nodular arteries, which cannot be flattened against the skull.
• Pulsation is initially present, but later ceases, a sign strongly suggestive of GCA, since a non-pulsatile superficial temporal artery is highly unusual in a normal individual.
• The best location to examine pulsation is directly in front of the pinna.
• In very severe cases, scalp gangrene may ensue.
• Rare complications include dissecting aneurysms, aortic incompetence, myocardial infarction, renal failure and brainstem stroke.

3. Erythrocyte sedimentation rate (ESR) is often very high, with levels of >60 mm/hr, although in approximately 20% of patients it is normal.

4. Blood platelet levels may be elevated.

5. C-reactive protein (CRP) is invariably raised and may be helpful when ESR is equivocal.

6. Temporal artery biopsy (TAB) should be performed if GCA is suspected.

• Steroids should never be withheld pending biopsy, which should ideally be performed within 3 days of commencing steroids.
• Systemic steroids for more than 7–10 days may suppress histological evidence of active arteritis although this is not invariable.
• In patients with ocular involvement it is advisable to take the biopsy from the ipsilateral side. The ideal location is the temple because it lessens the risk of major nerve damage.
• At least 2.5 cm of the artery should be taken and serial sections examined because of the phenomenon of ‘skip’ lesions in which segments of histologically normal arterial wall may alternate with granulomatous inflammation.

Treatment of giant cell arteritis

• Treatment involves systemic steroids, the duration of which is governed by symptoms and the level of the ESR or CRP.
• Symptoms may, however, recur without a corresponding rise in ESR or CRP and vice versa.
• Most patients need treatment for 1–2 years, although some may require indefinite maintenance therapy.
• CRP may play an important role in monitoring disease activity, as the level seems to fall more rapidly than the ESR in response to treatment.

Ophthalmic manifestations of giant cell arteritis

Arteritic anterior ischaemic optic neuropathy

AAION affects 30–50% of untreated patients of which one-third develop involvement of the fellow eye, usually within 1 week of the first.

Posterior ischaemic optic neuropathy is much less common.

1. Presentation 

• sudden, profound unilateral visual loss which may be accompanied by periocular pain and preceded by transient visual obscurations and flashing lights. 
• Bilateral simultaneous involvement is rare. 
• Most cases occur within a few weeks of the onset of GCA although at presentation about 20% of patients do not have systemic symptoms (i.e. occult GCA).

2. Signs

• Severe visual loss is the rule, commonly to LP or worse.
• A strikingly pale (‘chalky white’) oedematous disc is particularly suggestive of GCA. 
• Occasionally AAION may be combined with occlusion of the cilioretinal artery.
• Over 1–2 months, the swelling gradually resolves and severe optic atrophy ensues.

3. Treatment 

• aimed at preventing blindness of the fellow eye, although the second eye may still become involved in 25% of cases despite early and adequate steroid administration, usually within 6 days of starting treatment. 
• Visual loss is usually profound and is unlikely to improve even with immediate treatment. 
• The regimen is as follows: 
• (a) Intravenous methylprednisolone,
  1g/day for 3 days then oral prednisolone 1–2 mg/kg/day. After 3 days the oral dose is reduced to 60 mg and then 50 mg each, for one week.
  The daily dose is then reduced by 5 mg weekly until 10 mg is reached. 
• (b) Oral prednisolone alone may be administered as an alternative in some circumstances (e.g. late presentation or systemic contraindications to intravenous therapy). 
• (c) Antiplatelet therapy (e.g. aspirin 150 mg/day) should be commenced. 
• (d) Immunosuppressives may be used as adjuncts in steroid-resistant cases or as steroid-sparing agents when extended treatment is required. 

4. Prognosis 

• very poor because visual loss is usually permanent, although very rarely, prompt administration of systemic steroids may be associated with partial visual recovery.

Other manifestations

1. Transient ischaemic attacks (amaurosis fugax) may precede infarction of the optic nerve head. 

2. Cilioretinal artery occlusion may be combined with AAION. 

3. Central retinal artery occlusion is usually combined with occlusion of a posterior ciliary artery. This is because the central retinal artery often arises from the ophthalmic artery by a common trunk with one or more of the posterior ciliary arteries. However, ophthalmoscopy shows occlusion of only the central retinal artery; the associated ciliary occlusion can be detected only on FA.

4. Ocular ischaemic syndrome clinical picture due to involvement of the ophthalmic artery is rare. 

5. Diplopia, transient or constant, may be caused by ischaemia of the ocular motor nerves or extraocular muscles.