++
A stroke is any process that disrupts the flow of oxygen and substrate-rich blood to the brain. Neurons are very sensitive to changes in cerebral blood flow, and die within minutes. Commonly, an infarcted area of brain is surrounded by a region of tenuous blood flow, the ischemic penumbra. The focus of stroke management is to maintain the blood supply to this region, thereby limiting infarct size. Overall, 85% of strokes are ischemic and 15% are hemorrhagic.
+++
Anatomy of Cerebral Blood Flow (Figure 15.1)
++
Anterior circulation (from carotid arteries, 80% of cerebral blood flow [CBF])
Anterior cerebral: Frontal pole, anteromedial cerebral cortex, anterior corpus callosum
Middle cerebral: Frontoparietal lobe, frontotemporal lobe, language centers
Ophthalmic: Optic nerve and retina
Posterior circulation (from vertebrobasilar arteries, 20% of CBF)
Circle of Willis
++
++
Ischemic stroke may be divided into three types: Thrombotic, cardioembolic, and hypoperfusion states (Table 15.1).
++++
Q
A 58-year-old woman is brought to the emergency department (ED) as a “stroke alert.” Her husband states that she woke up 1 hour prior to arrival with slurred speech and weakness in her right arm and leg. On physical examination she has aphasia, right-sided hemiparesis, and sensory deficits. Laboratory test results are drawn, and the patient is rushed to the computed tomography (CT) scanner. What blood vessel is associated with this stroke syndrome? Is this patient a thrombolysis candidate?
++
Thrombosis is the most common cause of stroke in the United States and typically results from clot formation at the site of an ulcerated atherosclerotic plaque.
++
++
Vessel narrowing from vasculitis, dissection, infectious disease, vasospasm
Thrombophilia from hypercoagulable states
Sickle cell disease
Polycythemia
++
Symptoms generally come on gradually and may be preceded by transient ischemic attacks (TIAs) affecting the same region as the stroke.
++
A subset of thrombotic stroke is the lacunar stroke. This is a stroke of a small terminal vessel, typically deep in the subcortical cerebrum, basal ganglia, internal ...