Severe throbbing headache syndrome characterized by
inflammation of the temporal (pulseless, enlarged superficial artery) and
other cranial arteries. Patients present with anorexia, insomnia, and
low-grade fever. Blindness may occur if process reaches the ophthalmic
artery. Rarely presents before the sixth decade of life.
Arteritis Temporalis (of Horton); Horton Arteritis;
Horton Disease I; Horton Giant Cell Arteritis; Horton Temporal Arteritis;
Horton-Gilmour Disease; Horton-Magath-Brown Syndrome; Hutchinson-Horton
Syndrome; Giant Cell Arteritis (GCA); Granulomatosis Arteritis; Senile
Arteritis; Temporal Arteritis; Temporal Megacellular Arteritis.
NB: Do not confuse with Bing-Horton syndrome or Horton disease II (cluster
headache and erythroprosopalgia).
Systemic arteritis affecting major and small arteries.
First described by Jonathan Hutchinson in 1890.
More common in the northern latitudes (15-30:100,000
persons) compared to southern latitudes (<2:100,000 persons). Rather common
in northern Europe. Rare in nonwhites. Both sexes affected, but females
twice as often as males.
Not a genetic disorder even though genetic
factors may predispose to the disease (three allelic variants of the
HLA-DRB1*04 family are overrepresented in patients with biopsy-proven
disease). Familial aggregation has been observed. People of Hispanic descent
seem genetically protected against the syndrome.
The pathogenesis is not fully understood, but the
underlying cause of the inflammation is an autoimmune reaction to the lining
of temporal and related arteries (mainly the adventitia); however, Horton
syndrome cannot be considered an autoimmune disease. Histologically, there
is lymphocyte, plasma cell, and multinucleated giant cell infiltration of
the vessel wall. A cell-mediated autoimmune mechanism against elastin is
suggested. The cellular infiltrate predominantly consists of CD4 + T
lymphocytes and monocytes. High levels of IL-1 and IL-2 have been identified
in the lesions of Horton syndrome, as well as in polymyalgia rheumatica,
suggesting a common pathogenesis. Chlamydia pneumoniae may play a significant role (data suggest
the organism could be viable and undergo active vegetative growth in
temporal artery tissues in affected patients). Increased endothelin-1 plasma
levels have been reported, and the significance is under evaluation.
Positive temporal artery biopsy. Characteristic history
in the absence of biopsy.
General symptoms include weight loss, pyrexia
(may have acute onset), symmetrical muscle stiffness, and pain that is worse
in the morning. Cranial symptoms include paroxysmal burning pain (typically
unilateral and beginning behind one eye), headache, jaw claudication, rarely
scalp necrosis, or lingual ischemia secondary to arterial occlusion. Skin
overlying arteries may appear inflamed in the acute phase. Ocular problems
include blindness caused by anterior ischemic optic atrophy, transient
visual loss, and diplopia. The vasculitis increases the risk of aortic
aneurysm (usually thoracic/dissecting), coronary arteritis causing
myocardial ischemia, and cerebral arteritis causing infarction, most usually
in a posterior cerebral artery distribution. Vertebral arteritis may result
in auditory loss and vestibular dysfunction (vertigo). Abdominal
claudication and bowel necrosis are reported. Erythrocyte sedimentation rate
and C-reactive protein are elevated. Treatment consists of high-dose
glucocorticoid therapy in the acute phase, subsequently reduced to a lower