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Giant-cell arteritis (GCA or temporal arteritis or cranial arteritis) or Horton disease is an inflammatory disease of blood vessels most commonly involving large and medium arteries of the head, predominantly the branches of the external carotid artery. The most serious complication is occlusion of the ophthalmic artery, which is a branch of the internal carotid. It can create a medical emergency which can cause irreversible ischemia and blindness if not treated promptly. GCA is treated with glucocorticoids (steroids), which reduce the inflammation and prevent occlusion. No other drugs are effective or contribute to the effect of glucocorticoids.〔 GCA is a form of vasculitis. It typically causes inflammation of the network of small vessels (vasa vasorum) that supplies the larger arteries. GCA affects arteries of the head and neck, including the three arteries that branch out from the arch of the ascending aorta, and their branches—the thoracic aorta, the axillary arteries, the vertebral arteries, and further on in the head in the ophthalmic and external carotid arteries (the temporal and occipital arteries). It can cause occlusion of the arteries and ischemia. GCA is diagnosed with biopsy of the temporal artery. While the clinical presentation, patient characteristics and blood test markers of inflammation can raise suspicion, only a temporal artery biopsy can give definite diagnosis. Some cases may not involve the temporal artery, and distinguishing between a false negative and the absence of GCA is difficult.〔 The terms "giant-cell arteritis" and "temporal arteritis" are sometimes used interchangeably, because of the frequent involvement of the temporal artery. However, it can involve other large vessels (such as the aorta in "giant-cell aortitis"). Giant-cell arteritis of the temporal artery is referred to as "temporal arteritis," and is also known as "cranial arteritis" and "Horton's disease." The name (giant-cell arteritis) reflects the type of inflammatory cell involved as seen on a biopsy. ==Signs and symptoms== It is more common in women than in men by a ratio of 2:1 and more common in those of Northern European descent, as well as those residing at higher latitudes. The mean age of onset is >55 years, and it is rare in those less than 55 years of age. People present with: * bruits * fever * headache * tenderness and sensitivity on the scalp * Jaw claudication (pain in jaw when chewing) * tongue claudication (pain in tongue when chewing) and necrosis * reduced visual acuity (blurred vision) * acute visual loss (sudden blindness) * diplopia (double vision) * acute tinnitus (ringing in the ears) * polymyalgia rheumatica (in 50%) The inflammation may affect blood supply to the eye and blurred vision or sudden blindness may occur. In 76% of cases involving the eye, the ophthalmic artery is involved causing arteritic anterior ischemic optic neuropathy. It is important to be aware that giant-cell arteritis may present with atypical or overlapping features. Early and accurate diagnosis is important to prevent ischemic vision loss and therefore, this condition is considered a medical emergency.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Giant-cell arteritis」の詳細全文を読む スポンサード リンク
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