Stroke is defined as an acute neurologic deficit lasting more than 24 hours and caused by cerebrovascular etiology. It is subdivided into ischemic stroke (caused by vascular occlusion or stenosis) and hemorrhagic stroke (caused by vascular rupture, resulting in intraparenchymal and/or subarachnoid hemorrhage). Ischemic stroke accounts for 87% of all stroke cases, hemorrhagic stroke for 10%, and subarachnoid hemorrhage for 3%.
Regardless of the specific etiology, ischemic stroke occurs when blood supply in a cerebral vascular territory is critically reduced due to occlusion or critical stenosis of a cerebral artery. A minority of ischemic strokes are caused by cerebral sinus or cortical vein thrombosis. Risk factors strongly associated with ischemic stroke include older age, history of transient ischemic attack, history of ischemic stroke, family history of stroke at a young age, hypertension, smoking, diabetes mellitus, atrial fibrillation, comorbid cardiac conditions, carotid artery stenosis, sickle cell disease, and dyslipidemia.
Cause of a minority of ischemic strokes. Strong risk factors include older age, smoking, and history of cardiovascular disease. Carotid revascularization of moderate- or high-grade recently symptomatic carotid artery stenosis prevents future stroke. The benefit of revascularization for asymptomatic stenosis is less certain.
Transient ischemic attack (TIA) should be suspected in anyone who presents with sudden-onset, focal neurologic deficit that has completely resolved within 24 hours of onset and cannot be explained by another condition such as hypoglycemia. TIAs have considerable risk of early recurrent cerebral ischemic events. Strong risk factors include atrial fibrillation, valvular heart disease, congestive heart failure, hypertension, diabetes mellitus, carotid stenosis, other significant illnesses (such as a hypercoagulable state or vasculitis such as temporal arteritis), cigarette smoking, alcohol-use disorder, and older age. Evaluation and initiation of secondary prevention should occur rapidly.
Intracerebral hemorrhage is caused by vascular rupture with bleeding into the brain parenchyma, resulting in a primary mechanical injury to the brain tissue. In 2017, the global prevalence of intracerebral hemorrhage (ICH) was 17.9 million people. Strong risk factors include hypertension, older age, family history of ICH, hemophilia, cerebral amyloid angiopathy, anticoagulation, use of illicit sympathomimetic drugs, vascular malformations, and Moyamoya syndrome.
Typically asymptomatic until ruptured, resulting in a subarachnoid hemorrhage. Screening with noninvasive neuroangiography is recommended for at-risk populations. Strong risk factors include smoking, moderate-high level alcohol consumption, family history, previous subarachnoid hemorrhage, and heritable connective tissue disease.
A medical emergency where there is bleeding into the subarachnoid space. The most common cause of nontraumatic subarachnoid hemorrhage is rupture of an intracranial aneurysm. Strong risk factors include age ≥50 years old, female sex, hypertension, smoking, family history, alcohol misuse, and autosomal dominant polycystic kidney disease.
BMJ Publishing Group
This overview has been compiled using the information in existing sub-topics.
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