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.
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http://www.ajnr.org/content/36/1/91.full.pdf 3t mri reveals extra- and intracranial involvement in giant cell arteritis s. Siemonsen, c. Brekenfeld, b. Holst, a.-k. Kaufmann-buehler, j. Fiehler, and t.a. Bley ajnr am j neuroradiol 36:91–97 jan 2015