--- title: Giant cell arteritis description: What giant cell arteritis is, why it is dangerous for eyesight, how it is recognised, which treatment approaches clinical guidelines describe and when to call an ambulance. type: disease aliases: - GCA - temporal arteritis - cranial arteritis - Horton's disease sources: - tier: guideline org: aha-acc title: '2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines' year: 2022 doi: 10.1161/CIR.0000000000001106 url: https://doi.org/10.1161/CIR.0000000000001106 - tier: guideline org: minzdrav-rf title: Аневризмы грудной и торакоабдоминальной аорты year: 2025 url: https://cr.minzdrav.gov.ru/view-cr/919_1 - tier: guideline org: minzdrav-rf title: Ретинальные артериальные окклюзии year: 2025 url: https://cr.minzdrav.gov.ru/view-cr/1012_1 - tier: reference org: msd-manuals title: Giant Cell Arteritis (MSD Manual Professional Version) year: 2024 url: https://www.msdmanuals.com/professional/musculoskeletal-and-connective-tissue-disorders/vasculitis/giant-cell-arteritis - tier: reference org: msd-manuals title: Giant Cell Arteritis (MSD Manual Consumer Version) year: 2024 url: https://www.msdmanuals.com/home/bone-joint-and-muscle-disorders/vasculitic-disorders/giant-cell-arteritis sources_checked: 2026-10-14 review: null --- Giant cell arteritis (GCA) is chronic inflammation of the large and medium arteries of the head, neck and upper body. The arteries most often affected are the temporal arteries, the chest part of the aorta and the large arteries that branch off it to the neck. Other names for the disease are temporal or cranial arteritis and Horton's disease. Together with [Takayasu arteritis](../takayasu-arteritis/), GCA is classed as a large vessel vasculitis; these are the most common causes of inflammation of the aorta (aortitis). The main danger of GCA is sudden, permanent blindness, so treatment is started as soon as the disease is suspected.

The temporal arteries run past the temples and carry blood to part of the scalp and to the jaw muscles; in GCA the neighbouring branches of the carotid arteries become inflamed too, including those that supply the optic nerve. Normally the lumen of the artery is round and open, and the inner layer of its wall is thin.

In GCA the inner layer of the artery wall becomes markedly thickened, and the lumen narrows, sometimes until it is blocked. Inflamed segments of the artery often alternate with healthy ones. The tissues beyond the narrowing do not get enough blood: this is why, for example, the jaw muscles hurt when chewing, and if blood stops reaching the optic nerve, permanent blindness can come on suddenly.

## Why it happens The cause of the disease is unknown. Cells of the immune system build up in the artery wall and form clusters of inflammation called granulomas; sometimes these contain large cells with several nuclei (giant cells). The inner layer of the artery becomes markedly thickened, and the lumen narrows, sometimes until it is completely blocked. The inflammation is patchy: affected segments alternate with healthy ones. The arteries most often affected are the temporal and other arteries of the head, which are branches of the carotid arteries; less often, the branches of the aortic arch, the coronary arteries and the arteries of the arms and legs. The arteries inside the skull are usually not affected. The inflammation can also involve the aorta itself, mainly its arch and the descending chest part. GCA is a relatively common vasculitis in the United States and Europe. It affects people over 50, on average starting at about 70; women are affected more often than men. About 40–60% of people with GCA also have polymyalgia rheumatica, a condition in which the muscles are painful and stiff. GCA is a systemic vasculitis with focal transmural granulomatous inflammation, giant cells, intimal thickening and infiltrates of mononuclear cells, neutrophils and eosinophils; its key feature is the segmental distribution of infiltrates of T cells and histiocytes. According to MSD, mononuclear cell infiltrates in the adventitia form granulomas containing activated T cells and macrophages; multinucleated giant cells, when present, cluster near the disrupted elastic lamina; the intima is markedly thickened, with concentric narrowing and occlusion of the lumen. The disease predominantly affects arteries containing elastic tissue: the thoracic aorta, the large arteries emerging from it in the neck and the extracranial branches of the carotid arteries. ACC/AHA: Takayasu arteritis and GCA tend to affect the thoracic aorta, whereas IgG4-related disease most commonly affects the abdominal aorta. According to the Russian Ministry of Health guideline, CT angiography, MR angiography or PET/CT find vasculitic involvement of the aorta mainly in the arch and the descending thoracic aorta, and partly in the abdominal and iliac segments. ## Symptoms Symptoms may build up gradually over several weeks or start suddenly. There may be a fever (usually low-grade), tiredness, a general feeling of being unwell, weight loss for no obvious reason and sweating. The most common symptom is a severe, sometimes throbbing headache of a kind the person has not had before, most often at the temples or the back of the head. The scalp may hurt when touched or when the hair is brushed, and the arteries at the temples may be tender, swollen and bumpy to the touch. Other possible symptoms: - pain and tiredness in the jaw muscles soon after starting to chew, especially firm food; the tongue may hurt when eating or speaking; - double or blurred vision, large blind spots in the field of vision, a drooping eyelid, sudden blindness in one eye that clears within a few minutes; - with polymyalgia rheumatica, severe pain and stiffness in the neck, shoulders and hips, worse at night and in the morning. The most dangerous complication is permanent blindness: it can come on suddenly if blood stops reaching the optic nerve. A brief loss of vision in one eye can quickly turn into a lasting one, and without treatment the other eye may be affected too. Jaw pain when chewing and double vision are linked to a higher risk of blindness. Sometimes blood flow to the brain is blocked and a stroke occurs. The inflammation can damage the aorta, leading to a [thoracic aortic aneurysm](../thoracic-aortic-aneurysm/) or [aortic dissection](../aortic-dissection/). These are serious, often late complications that can progress without other symptoms. The headache may be temporal, occipital, frontal or diffuse. According to the Russian Ministry of Health guideline, GCA may present with sudden temporal headache, malaise with features of a systemic inflammatory response of unknown origin, shoulder and pelvic girdle weakness, and weight loss. Some patients are initially investigated for fever of unknown origin. Visual disturbances include diplopia, scotomas, ptosis and blurred vision; loss of vision is an ominous sign, while complete bilateral blindness is uncommon. Vision loss is caused by arteritis of branches of the ophthalmic artery or the posterior ciliary arteries, with ischaemia of the optic nerve; funduscopy may show ischaemic optic neuritis with pallor and oedema of the optic disc, cotton-wool spots and small haemorrhages, and later optic atrophy. According to the Russian Ministry of Health guideline on retinal artery occlusions, arteritic central retinal artery occlusion most often develops with temporal arteritis in GCA and in most cases is combined with arteritic optic neuropathy. Intermittent claudication may occur in the jaw muscles, the muscles of the tongue and the limbs. Narrowing or occlusion of the carotid or vertebrobasilar arteries and their branches can cause strokes and transient ischaemic attacks. Here the lumen is narrowed by the thickened, inflamed wall. Narrowing of the carotid artery caused by atherosclerosis is covered in the article on [carotid artery stenosis](../carotid-artery-stenosis/). Thoracic aortic aneurysms and aortic dissection are serious, often late complications of aortitis that may progress without symptoms. According to the Russian Ministry of Health guideline, GCA is one of the risk factors for pathological dilatation of the ascending aorta, and rupture of the aorta and/or its branches appears to be a rare complication. ## How it is diagnosed A doctor will suspect GCA if a person over 50 has a new headache, jaw pain when chewing, tenderness of the temples or scalp, an unexplained fever or anaemia (a low red blood cell count). The suspicion is stronger if there are signs of polymyalgia rheumatica. The doctor feels the temporal arteries to check whether they are hard, bumpy or tender, and listens to the arteries in the neck. Blood tests usually show inflammation: raised ESR and C-reactive protein, and anaemia is common. These results support the diagnosis. The diagnosis is confirmed by a temporal artery biopsy: after a local anaesthetic, a piece of the artery is removed through a small cut. Sometimes an ultrasound scan of the temporal arteries is enough instead of a biopsy, but its accuracy depends heavily on the specialist's experience and the equipment. Tests should not delay treatment: a biopsy remains informative if it is done within 2 weeks of starting treatment. An ultrasound scan is best done before treatment starts or within the first 5 days: after that it becomes less sensitive. So that involvement of the aorta and its branches is not missed, they are examined with CT or MRI, sometimes together with positron emission tomography (PET), when the diagnosis is made and then periodically, even without symptoms. According to MSD, GCA is suspected in a patient over 50 with a new headache, any new symptom or sign compatible with ischaemia of an artery above the neck, jaw muscle pain during chewing, temporal artery or scalp tenderness, or unexplained subacute fever or anaemia, especially with clinical and laboratory evidence of systemic inflammation. On examination there may be swelling and tenderness over the temporal arteries, sometimes nodularity or erythema, and sometimes the pulse in the artery cannot be felt; a temporal artery that rolls under the examiner's fingers rather than collapsing is abnormal. The large arteries of the neck and the branches of the aorta are checked for bruits. In most patients ESR and CRP are raised, and anaemia of chronic disease is common; occasionally the platelet count is raised and serum albumin and total protein are low; mild leukocytosis is non-specific. A segment that appears abnormal is biopsied if possible, because inflamed segments alternate with normal ones; usually the temporal artery on the symptomatic side is sampled; longer samples, up to 5 cm, increase the yield, and contralateral biopsy adds little. Colour Doppler ultrasound of the temporal artery performed by experts may show vessel wall oedema as a halo and in some patients can substitute for biopsy. ACC/AHA: in patients with large vessel vasculitis, prompt evaluation of the entire aorta and branch vessels with MRI or CT, with or without 18F-FDG PET, is recommended (class 1, C-LD). Imaging should be performed as soon as possible so that initiation of treatment is not delayed; the sensitivity of the methods decreases with the duration of treatment. According to the Russian Ministry of Health guideline, on CT angiography, MR angiography or PET/CT of the aorta the signal from the vessel walls largely disappears 3–5 days after the start of treatment, and the result may be read as negative despite ongoing inflammation. FDG-PET has a reported specificity for GCA-related aortitis as high as 100%, and CT angiography about 85%; on CT, inflammatory wall thickening may be mistaken for atherosclerosis; evidence on the role of MRI in GCA is limited. Diagnostic criteria for GCA in the ACC/AHA table: age over 50 years, recent-onset localised headache, temporal artery tenderness or pulse attenuation, ESR above 50 mm/h, and necrotising vasculitis on arterial biopsy; the diagnosis is established when 3 or more criteria are present (sensitivity and specificity above 90%). ## How it is treated Treatment is started urgently, as soon as the doctor suspects GCA, usually even before the biopsy: without treatment, blindness can develop. The doctor decides which medicines are needed, at what dose and for how long. Treatment quickly eases the symptoms and prevents loss of vision in most people. To preserve vision, how quickly treatment is started probably matters more than the dose of the medicines. But treatment does not reverse damage to the optic nerve that has already happened, so above all it protects the other eye. With treatment, most people recover fully, especially if they continue treatment as the doctor prescribed, but the disease can come back. How well treatment is working is checked regularly by how the person feels, by blood tests and by scans of the aorta. If complications develop in the aorta or its branches, such as an aneurysm, an endovascular procedure or open surgery may be needed; according to the guidelines, a planned procedure is carried out when the disease is quiet (in remission). The doctors decide whether a procedure is needed and which one. In arteritic retinal artery occlusion, according to the Russian Ministry of Health guideline, treatment is aimed above all at preventing loss of vision in the fellow eye, because recovery of vision in the affected eye is unlikely even with immediate treatment; early treatment is crucial to prevent irreversible ischaemic complications. Optic nerve infarction, once started, cannot be reversed. ACC/AHA and the Russian Ministry of Health guideline: in patients with active GCA, treatment efficacy should be periodically assessed by clinical symptoms, CRP and ESR, and imaging of the aorta (CT, MRI or PET) (ACC/AHA class 1, C-LD; Russian Ministry of Health guideline, I C). According to MSD, ESR alone should not be used to evaluate response to treatment and disease activity: in older patients other factors, such as monoclonal gammopathies, can raise it. According to ACC/AHA, a major relapse of GCA is a recurrence of clinical features of ischaemia (visual loss, jaw or limb claudication, stroke) or evidence of active aortic inflammation resulting in branch vessel stenosis, aortic aneurysm or dissection. Remission is the absence of new clinical symptoms, normalisation of inflammatory markers and no evidence of progressive dilatation or narrowing of the aorta and its branches on surveillance imaging; signs of vessel inflammation may persist even without clinical disease. In remission, elective endovascular or open surgical intervention to treat aortic and branch vessel complications is reasonable (ACC/AHA class 2a, C-LD; Russian Ministry of Health guideline, IIa C). The risk of elective intervention is lowest in remission; the decision is made by a multidisciplinary team. In remission with aortic involvement, ACC/AHA considers surveillance imaging with CT, MRI or PET reasonable (class 2a, C-EO). ## When to call an ambulance Sudden loss of vision is a dangerous emergency that needs immediate medical help. In GCA, even a brief loss of vision in one eye can quickly turn into permanent blindness. If vision is suddenly lost or gets worse, even briefly and in one eye, or if vision becomes blurred or double, call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK) straight away. Sometimes in GCA blood flow to the brain is blocked and a stroke occurs. If there are signs of a stroke (sudden weakness or numbness on one side of the body, difficulty speaking, a drooping face), call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK) straight away. The signs of dissection are described in the article on [aortic dissection](../aortic-dissection/). As with any heart or blood vessel condition, call an ambulance for fainting, chest pain or severe shortness of breath: this is the site's general safety rule, repeated at the bottom of every page. If a person over 50 develops a new headache, pain in the temples or scalp, or jaw pain when chewing, they should see a doctor without delay: when GCA is suspected, treatment is started straight away.