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The mystery of inflammation: Why does giant cell arteritis make large blood vessels vulnerable?
Giant Cell Arteritis (GCA), also known as temporal arteritis, is an autoimmune inflammatory disease that affects the large blood vessels. The condition usually develops in people over the age of 50, affecting about one in 15,000 people each year, and is more common in people over the age of 70. The incidence rate is generally higher in women than in men, and people of northern European descent are particularly susceptible to the disease. Giant cell arteritis affects not only the temporal artery but may also affect other large arteries, including the aorta, potentially leading to serious complications such as blindness or aortic aneurysms.
“Its cause is unknown, but it hinges on inflammation affecting the small blood vessels that supply the walls of the large arteries.”
Symptoms and complications
Common symptoms of giant cell arteritis include headache, temporal tenderness, pain in the jaw or tongue when chewing, decreased vision, and double vision. The most dangerous complications include blindness from ophthalmic artery blockage and the risk of aortic tear or aneurysm. Early diagnosis is crucial to prevent irreversible vision loss and, therefore, the condition is considered a medical emergency.
"In 76% of cases where the eye is affected, the ophthalmic artery is involved in causing necrotizing anterior ischemic optic neuropathy."
Pathological mechanism
The pathological mechanism of giant cell arteritis is still unclear. Inflammation gradually activates dendritic cells in small blood vessels, which then recruit T cells and macrophages to form granuloma infiltration. These infiltrates erode the media and lining of the arteries, leading to aneurysms and tears. Th17 cells among T cells and the interleukins (IL) they secrete play a key role in the progression of the disease, and this pathway can be inhibited by steroid treatment.
"Steroid treatment is usually started as soon as the diagnosis is suspected to prevent possible vision loss."
Diagnostic Methods
The gold standard for confirming giant cell arteritis is a temporal artery biopsy, in which a small portion of the vessel is removed under local anesthesia and examined microscopically for giant cell infiltration. Although a negative biopsy result does not necessarily exclude the diagnosis, the pattern of vascular involvement is patchy. A physical examination and laboratory tests, including lymphocyte sedimentation rate and C-reactive protein, are also important parts of the diagnostic process.
Treatment options
Current treatment for giant cell arteritis relies on high-dose steroids, primarily to prevent blockage of the ophthalmic artery, which can lead to permanent blindness. The dose of steroids is usually tapered gradually over 12 to 18 months. In addition to steroids, other possible treatments include anti-interleukin therapy such as tocilizumab, which is effective in reducing the recurrence rate of the disease.
EpidemiologyThe epidemiological characteristics of giant cell arteritis show that the disease mainly affects people over the age of 50, especially those over the age of 70. The incidence rate in women is about twice that in men, and studies have shown that about one-fifth of polymyalgia patients may also suffer from giant cell arteritis.
Life Impact
Giant cell arteritis not only affects patients' daily lives due to its symptoms, but the side effects during treatment may also lead to a decrease in quality of life. After treatment, patients often report that losing vision, experiencing severe pain, and feeling tired are important indicators of quality of life.
Conclusion
Although our understanding of giant cell arteritis has improved, its underlying causes remain a mystery of medical concern. Faced with this far-reaching disease, how will future treatments develop to prevent more patients from falling into the disaster of inflammation?
