Carotid artery disease causes

Carotid artery disease is one of the major causes of ischemic stroke. The predominant mechanisms by which it causes stroke are (a) arterial embolism from atherosclerotic plaques (b) hemodynamic changes, leading to watershed infarcts and (c) distal propagation of thrombus originating from acute carotid occlusion. ... 

Georg Friedrich Handel s recurrent stroke is a well-documented historical case of cerebrovascular disease. He suffered from repeated palsies on his right side accompanied by speech impairment occurring in stroke-like episodes that must be considered left hemispheric ischemic events, possibly caused by left internal carotid artery disease (Bazner and Hennerici 2004). 

Patients with arterial disease caused by atherosclerosis, carotid, coronary, aortic, or LEAD are prone to thrombosis. 

Approximately 75% of acute coronary events and 60% of recently symptomatic carotid artery disease are caused by disruption of an atheromatous plaque. Vulnerable plaques are metabolically active and histologically complex atheromas with thin fibrous caps that are prone to spontaneous... 

Increasing Oxygen. It was once believed that the cause of Alzheimer s dementia was poor oxygen snpply to the brain. This theory suggested that atherosclerosis, hard plaques of fat and calcium, accumulate in blood vessels and block the arteries that snpply the brain, depriving it of oxygen-rich blood. In fact, atherosclerosis does occnr in the carotid arteries that snpply the brain and is the most common cause of stroke and vascnlar dementia. There is no evidence that this mechanism is involved in the pathology of Alzheimer s disease. 

Thrombomodulin mutations are more important in arterial diseases than in venous diseases. The thrombomodulin polymorphism, G—>A substitution at nucleotide position 127 in the gene, has been studied regarding its relation with the arterial disease. The 25 Thr allele has been reported to be more prevalent in male patients with myocardial infarction than the control population (25). Polymorphism in the thrombomodulin gene promoter (-33 G/A) influences the plasma soluble thrombomodulin levels and causes increased risk of coronary heart disease (26). Carriership of the -33A allele was also reported to cause increased occurrence of carotid atherosclerosis in patients less than 60 years (27). 

MCA infarcts are mainly caused by cardioembolism, internal carotid artery (ICA) thrombosis, dissection or embolism and rarely (in Caucasians) by intrinsic MCA disease. MCA atherothrombotic territory infarctions related to intrinsic MCA disease often cause concomitant small cortical (territorial or borderzone) and subcortical infarcts (Min et al. 2000). 

Tenderness of the branches of the external carotid artery (occipital, facial, superficial temporal) points towards giant cell arteritis. Tenderness of the common carotid artery in the neck can occur in acute carotid occlusion but is more Ukely to be a sign of dissection, or arteritis. Absence of several neck and arm pulses in a young person occurs in Takayasu s arteritis (Ch. 6). Delayed or absent leg pulses suggest coarctation of the aorta or, much more commonly, peripheral vascular disease. Other causes of widespread disease of the aortic arch are atheroma, giant cell arteritis, syphihs, subintimal fibrosis, arterial dissection and trauma. 

Despite these limitations, duplex sonography is a remarkably quick and simple investigation in experienced hands, and it is neither unpleasant nor risky. Very rarely, the pressure of the Doppler probe on the carotid bifurcation can dislodge thrombus, or cause enough carotid sinus stimulation to lead to bradycardia or hypotension (Rosario et al. 1987 Friedman 1990). The same conceivably applies to the various arterial compression maneuvres that may be carried out during transcranial Doppler, and any such compression should be avoided in patients who may have carotid bifurcation disease. 

Innominate or proximal common carotid artery stenosis or occlusion is quite often seen on angiograms in symptomatic patients but, unless very severe, does not influence the decision about endarterectomy for any internal carotid artery stenosis. Although it is possible to bypass such lesions, it is highly doubtful whether this reduces the risk of stroke unless, perhaps, several major neck vessels are involved and the patient has low-flow cerebral or ocular symptoms. This very rare situation can be caused by atheroma, Takayasu s disease or aortic dissection. Clearly, close consultation between physicians and vascular surgeons is needed to sort out, on an individual patient basis, what to do for the best. 

Ischemic strokes account for around 80-85% of all strokes and are caused by arterial vascular occlusions rarely occlusion in the cerebral venous system may result in ischemic and/or hemorrhagic stroke. Arterial occlusions resulting from cerebral embolism are the most common causes of ischemic strokes, and by about one week after stroke as many as 70-90% of occlusions will have spontaneously recanalized. Emboli typically originate from atherosclerotic stenoses in the internal carotid artery or from sources in the heart such as clots in the left atrium or the left ventricle. Hypertension-induced vascular disease of the small perforating intracerebral arteries is a common cause of lacunar strokes. A classification of the major stroke subtypes is shown in Table 31.1. 

The study of cerebrovascular disease has advanced markedly in recent years with advances in non-invasive imaging methods such as MR angiography and CT angiography as well as an improved understanding of the immune system in the pathogenesis of atherosclerosis. Atherosclerotic cerebrovascular disease is a common cause of strokes and shows a predilection for sites such as the bifurcation of the common carotid artery into the internal and external carotid arteries and the aortic arch and the major intracranial arteries such as the basilar artery and the middle cerebral arteries. Occlusive atherosclerotic vascular disease of these large extracranial arteries is responsible for as many as 20-30% of ischemic strokes and intracranial steno-occlusive disease causes around 5-10% of ischemic strokes. 

Cerebrovascular disease is a consequence of hypertension. A neurologic assessment can detect either gross neurologic deficits or a slight hemiparesis with some incoordination and hyperreflexia that are indicative of cerebrovascular disease. Stroke can result from lacunar infarcts caused by thrombotic occlusion of small vessels or intracerebral hemorrhage resulting from ruptured microaneurysms. Transient ischemic attacks secondary to atherosclerotic disease in the carotid arteries are common in hypertensive individuals. 

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