Etiology Of Transient Ischemic Attacks

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Emboli of cardiac origin

Intracardiac thrombus or mass

Myocardial infarction (anterior wall sputum, akinetic segment) Cardiomyopathy (infectious, idiopathic) Arrhythmia (atrial fibrillation) Cardiac myxoma Valvular heart disease Rheumatic heart disease Bacterial endocarditis

Nonbacterial endocarditis (carcinoma, Libman-Sacks disease) Mitral valve prolapse Prosthetic valve

Vasculitides

Primary central nervous system vasculitis

Systemic necrotizing vasculitis (polyarteritis nodosa, allergic angiitis)

Hypersensitivity vasculitis (serum sickness, drug-induced, cutaneous vasculitis)

Collagen vascular diseases (rheumatoid arthritis, scleroderma, Sjogren disease)

Giant cell (temporal arteritis. Takayasu arteritis)

Wegener granulomatosis

Lymphomatoid granulomatosis

Behcet disease

Infectious vasculitis (neurovascular syphilis, Lyme disease, bacterial and fungal meningitis, tuberculosis, acquired immunodeficiency syndrome, ophthalmic zoster, hepatitis B)

Hematologic disorders

Hemoglobinopathies (sickle cell, sickle cell hemoglobin C [HbSC] Hyperviscosity syndromes (polycythemia, thrombocytosis, leukocytosis, macroglobulinemia. multiple myeloma) Hypercoagulable states (carcinoma, pregnancy, puerperium) Protein C or S deficiency

Antiphospholipid antibodies (lupus anticoagulant, anticardiolipin antibody)

Drug related

Street drugs (cocaine, crack, amphetamines, lysergic acid, phencyclidine, methylphenidate, sympathomimetics, heroin, pentazocine)

Alcohol

Oral contraceptives

Other

Fibromuscular dysplasia

Arterial dissection (trauma, spontaneous, Marfan syndrome)

Homocystinuria

Migraine

Subarachnoid hemorrhage or vasospasm Other emboli (fat, bone marrow, air) Moyamoya should include a funduscopic examination. In this patient, the first symptom was amaurosis fugax due to cholesterol emboli, called Hollenhorst plaques, which often can be seen lodged in the retinal artery. Auscultation for carotid bruits, cardiac murmurs, assessment of cardiac rhythm, evidence of embolic events to other parts of the body, and a complete neurologic examination should also be assessed.

Laboratory data that should always be obtained include a complete blood count, fasting lipid profile, and serum glucose level. Other laboratory data, such as an erythrocyte sedimentation rate in elderly populations to evaluate for temporal arteritis, should be tailored to the demographic of the patient. Generally, a 12-lead ECG must be obtained to evaluate for atrial fibrillation. An echocardiogram can be useful to evaluate for valvular or mural thrombi. A noncontrast CT scan of the brain also must be performed initially. Noncontrast CT scans of the brain are very sensitive in detecting acute cerebral hemorrhage but are relatively insensitive to acute ischemic strokes, particularly when the area of the stroke is <5 mm in diameter, are located in the region of the brainstem, or are <12 hours old. Further imaging with magnetic resonance may be considered.

Finally, imaging of the extracranial vasculature to detect severe carotid artery stenosis is essential to guide further stroke prevention therapy. The gold standard for imaging of extracranial and intracranial vasculature is cerebral angiography. However, carotid Doppler ultrasound and magnetic resonance angiography are effective noninvasive imaging studies and are often used as a first-line diagnostic tools.

Stroke prevention begins with antiplatelet therapy, and aspirin should be used in all cases unless there is a contraindication to its use. Use of clopido-grel or combination aspirin and dipyridamole may be slightly superior to aspirin for stroke prevention but at a substantially higher dollar cost. Combination therapy with aspirin and clopidogrel has not been shown to provide greater benefit in stroke prevention but does produce a higher rate of bleeding complications. For patients with TIA/stroke as a consequence of carotid atherosclerosis, medical management includes antiplatelet agents, blood pressure control, treatment of hyperlipidemia, and smoking cessation. For patients with cardioembolic stroke as a result of atrial fibrillation, long-term anticoagulation with warfarin (Coumadin) is recommended. For patients with small-vessel disease producing lacunar infarctions, blood pressure control and antiplatelet agents are the mainstays of therapy.

Surgical endarterectomy for severe carotid artery stenosis has successfully reduced the long-term risk of stroke in both symptomatic and asymptomatic patients. The North American Symptomatic Carotid Endarterectomy Trial (NASCET) showed that in patients who had suffered a TIA or stroke and had ipsilateral carotid artery stenosis >70%, endarterectomy reduced the rate of stroke from 26% to 9% over 2 years compared with standard medical management. The Asymptomatic Carotid Artery Stenosis (ACAS) trial also showed benefit from carotid endarterectomy in patients with asymptomatic carotid artery stenoses (those with prior TIA or stroke), >60%. However, the risk reduction was smaller than in symptomatic patients, from 11% to 5% over 5 years compared to medical management. It should also be noted that the surgery is not without risk and can actually cause strokes. In both trials, the stipulation was made that in order to achieve the risk reduction benefit, surgery should be performed in a center with very low surgical morbidity and mortality. For asymptomatic patients, the benefits of the procedure do not begin to exceed the perioperative morbidity for at least 2 years, so it should be viewed as a "long-term investment" in patients with relatively low comorbidity and a long life expectancy. Carotid angioplasty and stenting is another procedure available for patients with carotid stenosis but, like endarterectomy, also carries a substantial risk of embolization and stroke. Angioplasty has not been proven to be superior to surgical endarterectomy, and its exact role is not yet defined. It may be considered as an alternative to surgery for symptomatic patients, those with previous TIA or stroke, whose surgical risk is believed to be too high or who are believed to have a high risk for restenosis.

Comprehension Questions

[47.1] A healthy 55-year-old man without prior history of stroke or TIA is seen for his annual physical examination. He is found to have a right carotid bruit. On duplex ultrasound, he is found to have a 75% stenosis of the right carotid artery. Which of the following is the best therapy?

A. Aspirin

B. Warfarin (Coumadin)

C. Carotid endarterectomy

D. Observation and reassurance

[47.2] One year ago, a 24-year-old woman had an episode of diplopia of 2 weeks' duration. The symptoms resolved completely. Currently, she complains of left arm weakness but no headache. Which of the following is the most likely diagnosis?

A. Recurrent transient ischemic attacks

B. Subarachnoid hemorrhage

C. Complicated migraine

D. Multiple sclerosis

[47.3] A 67-year-old woman with extensive atherosclerotic cerebrovascular disease complains of dizziness and vertigo. Which of the following arteries is most likely to be affected?

A. Vertebrobasilar

B. Carotid

C. Aorta

D. Middle cerebral

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