Temporal Artery Biopsy

Temporal artery biopsy removes a segment of the superficial temporal artery to diagnose giant cell arteritis, a large and medium vessel vasculitis in people over 50. The artery is easy to reach and often involved, and biopsy is the reference test, because treatment is long and carries real risks.

Giant cell arteritis causes new headache, scalp tenderness, jaw claudication, visual symptoms, and polymyalgia rheumatica. It can cause sudden, permanent blindness through ischaemia of the optic nerve, and this is the main reason for urgent treatment. Stroke and aortic aneurysm are further complications.

The procedure is done under local anaesthesia as a day case and takes 20 to 40 minutes. A segment of artery of 1 to 2 cm (at least 1 cm after fixation) is removed from the frontal or parietal branch. The report is available in 3 to 7 days.

A positive biopsy confirms the diagnosis, with a specificity close to 100%. The sensitivity is about 75 to 90%, because the inflammation is patchy ("skip lesions") and some people have disease in larger vessels with a normal temporal artery. A negative biopsy does not exclude the disease, and the clinical picture, blood tests and imaging are weighed together.

Indications.

• Suspected giant cell arteritis, with age over 50 and new headache, scalp tenderness, jaw or tongue claudication, visual loss or double vision, raised inflammatory markers, or polymyalgia rheumatica with systemic features.
• Unexplained fever, anaemia and a high erythrocyte sedimentation rate in an older adult.
• Cases where imaging (ultrasound or MRI) is unavailable, equivocal or does not agree with the clinical picture.
• Confirmation of the diagnosis before long term corticosteroid treatment.
• Suspected vasculitis in the temporal artery in younger patients, with specialist input.

Not indicated when the clinical picture is classic and ultrasound shows the typical halo sign, in services where imaging is accepted for diagnosis. It is also not a reason to delay treatment when vision is threatened.

Contraindications and precautions.

• Treatment is not delayed to wait for biopsy. High dose corticosteroids are started as soon as the diagnosis is suspected, especially with visual symptoms.
• Biopsy is done within 1 to 2 weeks of starting steroids when possible. The yield stays reasonable for 2 to 4 weeks, though inflammation fades with treatment.
• Bleeding disorder and anticoagulation: manageable with care in this superficial site.
• Overlying skin infection or a scalp rash.
• Previous scalp surgery or occlusion of the artery, and a very tortuous artery.
• Collateral supply to the eye and the scalp is good, but a persistent facial or scalp deficit is possible, so the facial nerve branch is protected.

Preparation and technique.

Consent explains the risk of a false negative result, scalp numbness, facial nerve injury, scarring and bleeding. The side with the more tender or symptomatic artery is chosen, or the side with the clearest ultrasound abnormality. The pulse is palpated, and a hand held Doppler can mark the artery.

Hair is clipped, the area is cleaned, and local anaesthetic is infiltrated around, and not into, the artery. A 3 to 4 cm incision is made along the artery in the pre-auricular or parietal area. The artery is exposed, branches are tied, and a segment of 1.5 to 2 cm is removed, with the ends ligated. The skin is closed with sutures.

The specimen is placed in formalin without crushing and without stretching, and sent with the clinical details and the steroid start date. A contralateral biopsy is done at the same time or later when the first is negative and suspicion remains high, which raises the yield by about 5 to 10%. Sutures are removed in 7 to 10 days.

Normal appearances.

A normal temporal artery shows a thin intima, an intact internal elastic lamina in a continuous wavy layer, a muscular media, and an adventitia, with no inflammatory cells. Age related intimal thickening and calcification are common in older adults.

Interpretation.

• Active giant cell arteritis: a transmural inflammatory infiltrate with lymphocytes, macrophages and multinucleated giant cells, usually around the internal elastic lamina, which is fragmented. Intimal hyperplasia narrows the lumen. Giant cells are seen in about half of positive biopsies, and are not needed for the diagnosis.
• Healed (burnt out) arteritis: fragmented internal elastic lamina with scarring, neovascularisation and a few remaining inflammatory cells, in patients who have had steroids or have long standing disease. It still supports the diagnosis.
• Granulomatous or necrotising vasculitis of small vessels: points to other vasculitides (polyarteritis, ANCA-associated vasculitis).
• Atherosclerosis and senile changes: calcification and intimal fibrosis without inflammation, which are not arteritis.
• Negative biopsy: no arteritis in the segment examined. When the clinical probability is high, treatment continues, and imaging or a second biopsy is used.
• Segment length: the report states the length, and a short segment (under 0.7 to 1 cm) lowers the yield. Multiple levels through the specimen are examined, because of skip lesions.

Critical values and findings needing immediate action.

• Visual loss, double vision or amaurosis fugax with suspected giant cell arteritis: emergency treatment with high dose corticosteroids and urgent ophthalmology assessment, before the biopsy result.
• Stroke or transient ischaemic attack symptoms: urgent neurology review.
• Positive biopsy: start or continue long term steroids, with bone, gastric and glucose protection.
• A chest or back pain, a new murmur, arm claudication or asymmetric blood pressure: assess for aortitis and large vessel involvement.

Limitations and artefacts.

• Skip lesions and a short segment cause false negatives, and sensitivity is 75 to 90%.
• Steroids given for more than 2 to 4 weeks reduce the yield, though a positive result is possible for months.
• Disease limited to the aorta and its branches (large vessel giant cell arteritis) gives a normal temporal artery.
• Crush artefact, poor orientation or a very short specimen limit the pathologist.
• Healed disease can be misread as atherosclerosis, and senile changes can mimic arteritis.
• Complications: scalp haematoma, infection, wound breakdown, scarring, scalp numbness, facial nerve (frontal branch) weakness, and, very rarely, scalp necrosis or stroke.
• Biopsy depends on surgical skill, and a vascular or ophthalmic service may be needed.
• Raised erythrocyte sedimentation rate and C-reactive protein are not specific. About 5 to 10% of people with the disease have normal markers.

Special groups.

• Patients over 50 with new headache: age alone raises the suspicion, and inflammatory markers are checked at the first visit.
• Patients with polymyalgia rheumatica: giant cell arteritis coexists in about 15 to 20%, and symptoms of cranial involvement are asked about.
• Patients on corticosteroids for another reason: the yield is lower, and imaging helps.
• Patients with diabetes, osteoporosis or peptic ulcer: more risk with long steroid treatment, and prophylaxis is planned.
• Younger patients (under 50): consider Takayasu arteritis and other vasculitis.
• Regions: giant cell arteritis is less often reported in Africa and Asia than in northern Europe, and diagnosis often relies on the clinical picture, raised erythrocyte sedimentation rate and response to steroids. Ultrasound of the temporal arteries is the practical alternative where a surgeon and a pathologist are not available. Corticosteroid side effects are a particular problem where monitoring is limited.

Follow up tests.

• Erythrocyte sedimentation rate, C-reactive protein, full blood count (platelets, haemoglobin) and liver function tests.
• Ultrasound of the temporal and axillary arteries (halo sign).
• MRI and CT angiography, and PET-CT of the aorta and its branches for large vessel disease.
• Ophthalmology examination with fundoscopy.
• Bilateral biopsy if the first is negative and suspicion is high.
• Blood pressure in both arms, and chest imaging for aortic aneurysm during follow up.
• Bone density, glucose and lipids during steroid treatment.
• Specialist rheumatology review and steroid sparing treatment decisions.