You’re blind and your hair is a mess

Anterior ischemic optic neuropathy (AION) due to giant cell arteritis

The history and examination is classic for giant cell arteritis, and papilloedema is evident on funduscopy.

History:

• visual loss: sudden and painless, can be severe and bilateral, may be preceded by amaurosis fugax. 1/2 unilateral, 1/3 sequential, 1/6 bilateral.
• local symptoms: temporal headache, scalp tenderness (pain on combing hair), jaw claudication (pain with chewing)
• systemic symptoms: fever and night sweats,  weight loss, malaise, anorexia
• polymyalgia rheumatica: generalised muscle pain and weakness, predominatly affects the muscles of the limb girdles
• age >50y (very rare younger than this, incidence rises with age)
• assess for factors that may complicate steroid treatment – e.g. peptic ulcer disease, GI bleeding, poorly controlled diabetes, Tb.

Examination:

• Visual acuity — poor e.g. CF only
• Visual fields — defect may be present, respects the horizontal meridian (‘altitudinal’) or central
• External examination — palpable and tender non-pulsatile temporal artery
• Pupils — RAPD
• Fundoscopy — papilloedema and flame-shaped hemorrhages may be seen, optic atrophy occurs late

Referral to ophthalmologist and arrange:

Immediate ESR/CRP (can be normal!)  – thrombocytosis may also be present

Urgent treatment with corticosteroids: start when the diagnosis is suspected, do not wait for confirmation.

• use high-dose IV methyprednisolone initially — e.g. 250 mg IV q6h for 72 hours — more effective than oral prednisone in promoting recovery of vision and preventing the fellow eye from being affected; 1/3 with visual loss will recover.
• follow with oral prednisolone ~ 1mg/kg until GCA ruled out, or until symptoms improve and ESR normalises — then a reducing dose over 6-12+ months is commonly used.
• consider ulcer prophylaxis and risk of osteoporosis.

Temporal artery biopsy to confirm the diagnosis of GCA

• perform within 1 week of symptom onset.
• if negative on a 2cm biopsy but GCA is highly suspected, biopsy the other temporal artery
• if negative stop treatment with prednisolone unless the presentation is classic and responded to steroid

A guide to the upper limit of normal ESR is:

• age/2 for men
• (age + 10)/2 for women

In addition to arteritic ischemic neuropathy (which is commonly caused by GCA, but can occur in other forms of vasculitis), there is also:

• Non-arteritic ischemic optic neuropathy: presents similar to arteritic ION but is usually less severe, and is without the systemic features or scalp/ facial symptoms. It is generally idiopathic, although may be linked to typical cardiovascular risk factors. The condition may be progressive or non-progressive and it is unclear if steroids are beneficial.
• Postoperative ischemic optic neuropathy: occurs within 1 week of general anesthesia and is of uncertain etiology. It is associated with many different types of surgery, as well as head-down positioning and prolonged operative times. Correction of intra-operative hypotension and anemia may be beneficial.

• optic neuritis
• other optic neuropathies — e.g. glaucoma, compressive optic neuropathy, radiation optic neuropathy, metabolic and toxic optic neuropathies
• central retinal vein occlusion
• central retinal artery occlusion
• chiasmal and post-chiasmal visual loss