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A large vessel essentially refers to the aorta and its largest branches that are directed to the head and neck and the extremities. The hallmark of pathology associated with large vessel vasculitides is that chronic inflammatory lesions are primarily found inside of the walls of vessels and not on the outside.
This is a key distinction that can be used in order to separate large vessel pathology from small vessel pathologies, which present with inflammation on the outside of the vessel wall in addition to being found within. The two main large artery vasculitides that will be discussed below are giant cell arteritis (GCA) and Takayasu arteritis (TA).
Also known as temporal arteritis or Horton’s arteritis, giant cell arteritis is a fairly common systemic vasculitide with a higher prevalence in women and peak incidence almost exclusively after the fifth decade of life. GCA typically has a gradual onset, but an abrupt one is not unheard of. Moreover, it is often associated with polymyalgia rheumatic (an inflammatory disorder causing muscle pain). Most of GCA’s clinical manifestations occur prior to therapy with steroids; however, they may develop during the early phase of treatment or while gradually reducing the dosage of steroid therapy. In addition, a constitutional syndrome consisting of loss or lack of appetite, abnormal physical weakness or lack of energy and weight loss may also commonly occur.
Additional symptoms associated with GCA are carotidynia (carotid artery pain) and the thickening of erythematous, nodular, and tender superficial temporal arteries that may have decreased or absent pulses. Other arteries such as the postauricular, facial and occipital may also be enlarged, with fairly frequent claudication (pain induced by movement due to vessel obstruction) of the jaw. Due to the intense vessel occlusion associated with GCA and the resulting complication of blindness in up to 20% of patients, the condition is considered a medical emergency. Ocular manifestations also indicate increased risk for central nervous system complications such as ischemic stroke. Steroid therapy with calcium and vitamin D supplements is the cornerstone of treatment for GCA. Moreover, in terms of prognosis, there is no associated increase in mortality of patients who are treated with timely diagnosis and appropriate management.
TA, like GCA, is a chronic idiopathic as well as a granulomatous vasculitide that principally manifests as a panaortitis. TA leads to segmental stenosis of the vessel, occlusion and dilatation and/or the formation of an aneurysm. The progression of the disorder happens in a three phases, namely (i) systemic phase characterized by the constitutional syndrome similar to the constitution syndrome of GCA, (ii) vasculitic phase where the effects of phase one are compounded with vascular tenderness or pain, and (iii) burnt-out phase that manifests as a fibrotic, pulseless condition due to stenosis of the arteries. In addition to the constitutional syndrome symptoms, patients eventually present with hypertension, bruit sounds heard on auscultation and claudication of the upper and lower extremities.
In stark contrast to GCA, which has a peak incidence in individuals older than 50 years, TA is more prevalent in young adults in the 20s and 30s and has a predilection for females. As is the case with GCA, no predisposing factors have been clearly identified for TA; however, an autoimmune-mediated basis has been suggested by some studies. The mainstay of treatment for TA is corticosteroid therapy, but patients failing to respond may be treated with agents such as methotrexate or interventional surgical procedures that involve balloon dilation and / or stenting.