Stroke and Cerebrovascular Neurology
The Vascular Brain
Stroke as a Time-Dependent Tissue Disorder
Stroke is a neurologic emergency in which outcome depends on the balance between ischemic core, penumbra, collateral flow, and recanalization time. Modern stroke care uses imaging and physiology to estimate tissue viability rather than relying only on clock time.
Ischemic vs Hemorrhagic Stroke
Ischemic stroke
- Caused by arterial occlusion or hypoperfusion
- Often treated with thrombolysis and thrombectomy in selected patients
- Mechanisms include cardioembolism, atherosclerosis, small vessel disease
Hemorrhagic stroke
- Caused by vessel rupture or bleeding diathesis
- Management emphasizes blood pressure control, hemostasis, and neurosurgical assessment
- Common causes include hypertension, amyloid angiopathy, aneurysm
Penumbra and Collateral Flow
The ischemic penumbra is tissue that is functionally impaired but potentially salvageable. Collateral circulation can prolong survival of threatened tissue and is a major determinant of response to reperfusion therapy.
Which imaging concept is most associated with identifying potentially salvageable ischemic tissue?
Perfusion-diffusion mismatch and related methods are used to estimate salvageable tissue.
Correct answer: Penumbra imaging
What is the most important determinant of penumbral survival?
Better collaterals and faster recanalization preserve threatened tissue.
Correct answer: Collateral blood flow and timely reperfusion.
Acute Stroke Evaluation
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Step 1: Establish last-known-well time and symptom onset pattern.
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Step 2: Rule out hemorrhage and major mimics with emergent imaging.
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Step 3: Assess vessel occlusion and tissue viability where appropriate.
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Step 4: Select reperfusion, hemostatic, or neurocritical interventions based on mechanism.
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Step 5: Initiate secondary prevention targeted to etiology.
Which mechanism is most characteristic of lacunar stroke?
Lacunar infarcts arise from pathology of small penetrating arteries, often due to chronic hypertension or diabetes-associated arteriopathy.
Correct answer: Small vessel lipohyalinosis or arteriolosclerosis
Open Problems
Key frontier problems include better prediction of tissue fate, individualized thrombectomy selection, biomarker-guided secondary prevention, and improved therapies for hemorrhagic stroke and cerebral small vessel disease.