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Stroke is the fifth leading cause of death and a leading cause of disability in the United States. Time-critical recognition and treatment are essential — 'time is brain,' with approximately 1.9 million neurons lost every minute in untreated large vessel occlusion.
Ischemic stroke (87% of cases) results from thrombosis or embolism occluding cerebral blood flow, causing irreversible infarction in the ischemic core within minutes. The ischemic penumbra — electrically silent but potentially salvageable tissue — is the target of reperfusion therapy. Hemorrhagic stroke from intracerebral hemorrhage or subarachnoid hemorrhage involves direct tissue injury and hematoma expansion.
The BE-FAST mnemonic (Balance, Eyes, Face, Arm, Speech, Time) guides rapid identification. NIHSS quantifies deficit severity and guides therapy decisions. IV alteplase is indicated within 4.5 hours of onset in eligible patients; mechanical thrombectomy extends to 24 hours in select cases with favorable perfusion imaging. Key differentials include Todd's paralysis post-seizure, hypoglycemia mimicking stroke, brain tumor, and complex migraine. ABCD2 score risk-stratifies TIA for stroke risk.
Key imaging focus: Hyperdense vessel sign, loss of grey-white differentiation, ASPECTS score, CTA occlusion
Common clinical reasoning questions about this topic
BE-FAST stands for Balance (sudden loss), Eyes (vision changes), Face drooping, Arm weakness, Speech difficulty, and Time to call emergency services. It is used for rapid prehospital stroke recognition.
IV alteplase (tPA) is indicated within 4.5 hours of symptom onset in eligible patients. Mechanical thrombectomy for large vessel occlusion can be performed up to 24 hours from onset in select patients with favorable perfusion imaging.
CT head without contrast is the first imaging study and immediately identifies hemorrhage (hyperdense). Ischemic stroke may appear normal on initial CT. MRI diffusion-weighted imaging (DWI) is more sensitive for early ischemic changes.