In a 58-year-old patient with a three-week history of vertex headache and new blurred vision, what examinations and investigations should be performed in the UK to evaluate suspected giant-cell (temporal) arteritis?

Examination and Investigations for Suspected Giant Cell Arteritis in the UK

In this 58-year-old with vertex headache and blurred vision, you must immediately check ESR/CRP, perform a focused temporal artery examination, and arrange urgent temporal artery ultrasound within 24 hours while starting high-dose prednisolone 40-60 mg daily without delay if clinical suspicion is high.

Immediate Clinical Examination

Perform a targeted physical examination looking specifically for 1:

• Temporal arteries: Palpate for tenderness, thickening, nodularity, or reduced/absent pulsation
• Scalp tenderness: Check for pain when touching the scalp or combing hair
• Jaw claudication: Ask about pain with chewing or talking
• Visual examination: Document visual acuity, check for relative afferent pupillary defect, and look for signs of anterior ischaemic optic neuropathy
• Upper limb pulses and blood pressure: Check both arms for pulse inequality or bruits (particularly axillary)
• Constitutional symptoms: Document weight loss, fever, night sweats, fatigue

Essential Laboratory Tests

Order immediately 2:

• ESR and CRP: Elevated in >95% of GCA cases; normal values should raise suspicion for alternative diagnosis
• Full blood count
• Liver and renal function
• Consider full metabolic panel

Critical caveat: Do not wait for test results to start treatment if clinical suspicion is high, especially with visual symptoms 1.

Imaging - First-Line Diagnostic Test

Temporal artery ultrasound is the recommended first-line imaging test 3, 4:

• Should be performed within 24 hours of presentation 1
• Look for the characteristic "halo sign" (non-compressible hypoechoic wall thickening)
• Sensitivity 88%, specificity 97% when performed by experienced operators 2
• Can be done at point-of-care in fast-track clinics
• Remains diagnostic even if performed within 1-3 days after starting steroids 3

If ultrasound is unavailable or negative but clinical suspicion remains high 1:

• MRI of cranial arteries (shows circumferential wall thickening)
• PET-CT (particularly useful for large vessel involvement; remains sensitive up to 72 hours after steroid initiation) 3
• CT angiography (alternative for large vessel assessment)

Temporal Artery Biopsy

Reserve biopsy for 2, 5:

• High-risk patients with negative ultrasound but persistent clinical suspicion
• When imaging is unavailable or inconclusive
• Biopsy should be ≥1 cm length (0.7 cm post-fixation minimum)
• Can show features of GCA even weeks after starting steroids 1
• Do not delay treatment waiting for biopsy 2
• Contralateral biopsy not routinely indicated 2

Treatment Initiation - Do Not Delay

Start treatment immediately based on clinical suspicion 1:

• With visual symptoms: Consider IV methylprednisolone 0.25-1g daily for up to 3 days, then oral prednisolone 40-60 mg daily 1
• Without visual symptoms: Oral prednisolone 40-60 mg daily 1
• Do not withhold treatment pending diagnostic tests - delaying glucocorticoids when visual symptoms are present is the strongest risk factor for permanent blindness 1

Urgent Referral Pathway

Refer to specialist centre/fast-track clinic 1:

• Same-day or next-day for patients with visual symptoms
• Within 24 hours for all suspected GCA cases
• Fast-track clinics with immediate access to ultrasound have reduced permanent vision loss 3, 4

Common Pitfalls to Avoid

1. Waiting for biopsy results before starting steroids - this increases blindness risk
2. Assuming normal ESR/CRP rules out GCA - while rare, it can occur, especially with ischaemic complications
3. Delaying imaging beyond 72 hours of steroid initiation - sensitivity drops significantly after this window 3
4. Performing inadequate biopsy length - must be ≥1 cm
5. Missing large vessel involvement - consider PET-CT or MRI if cranial imaging negative but suspicion high

The key principle: This is a medical emergency requiring immediate treatment to prevent irreversible blindness. Diagnostic confirmation should proceed in parallel with, not before, treatment initiation 1, 2.