stroke and radiology Flashcards
Most common cause of ischemic stroke
1/3 are from emboli: artery to artery (carotid/vertebral/aortic arch or intracranial stenosis) or cardiac source ( Afib, dilated cardiomyopathy, endocarditis/valvular dz)
Treatment of ischemic stroke
Primary/secondary prevention: treat HTN, DM, hypercholesterolemia, prophylactic treatment of carotid artery stenosis. Tertiary treatment: minimize long term effects from acute stroke
Describe cell death following stroke (ie. How long it takes to begin and how many cells die)
Cell death will begin in less than 5 minutes under normal conditions. 2 million neurons die per minute
Differential for sudden onset neurological deficit
Infarct, Transient ischemic attack, Seizure – post-ictal, Hematoma, Neoplasm
Time course of IV thrombolytic therapy
Need to know if there is ischemic but not infarcted brain tissue in <4.5 hrs.
Stroke protocol
Noncontrast head CT, Perfusion CT, CT angiogram of head and neck
What is non contrast CT used for in stroke
(look for hematoma, hemorrhage, neoplasm, large infarct or other contraindication for antithrombolytic agent)
What is perfusion CT
Using an intravenous contrast bolus determine the amount of blood flow, blood volume and timing of the bolus to areas of the brain. Continuous imaging at 2 or 4 locations for about 1 minute. High dose of radiation
Perfusion CT algorithm for strokes
Increased time to start or mean transit time,
increased time to peak and decreased blood volume equals completed infarct. Increased time to start, increased time to peak and normal or increased blood volume equals brain at risk Increased time to start or mean transit time,
increased time to peak and decreased blood volume equals completed infarct. Increased time to start, increased time to peak and normal or increased blood volume equals brain at risk
CT angiogram -what is it
Using an intravenous contrast bolus and thin sections moving through the anatomy depict vascular anatomy
What does a CT of an infarct look like
Confined to a vascular territory. 1- 6 hours: loss of gray matter density. 6 hours – 4 days: progressive swelling and hypodensity. 4 – 14 days: return towards normal density and volume. 14 days on: – varying degrees of
hypodensity and volume lossConfined to a vascular territory. 1- 6 hours: loss of gray matter density. 6 hours – 4 days: progressive swelling and hypodensity. 4 – 14 days: return towards normal density and volume. 14 days on: – varying degrees of
hypodensity and volume loss
What does an infarct look like on MRI
1 hour – 10 days: bright on diffusion weighted imaging
Swelling and increased signal on FLAIR and T2-weighted scans follows same pattern as swelling ang and low density on CT. DWI great for small infarcts and telling new from old1 hour – 10 days: bright on diffusion weighted imaging
Swelling and increased signal on FLAIR and T2-weighted scans follows same pattern as swelling ang and low density on CT. DWI great for small infarcts and telling new from old
What is the NIH stroke scale
Score from 0-42 (higher score means greater neurological deficit). Based on Level of consciousness, language, gaze, extinction, face, motor, ataxia
Acute stroke treatment
IV thrombolytics – tpa: NINDS trial - established
benefit to administration within 3 hr window. Some evidence for extending window to 4.5 hrs
Intra-arterial thrombolytics: IA thrombolysis shown
beneficial up to 6 hrs. 2 FDA approved devices for
mechanical intracranial embolectomy (MERCI and
Penumbra). Several devices used off label
(balloons and stents) or in developmentIV thrombolytics – tpa: NINDS trial - established
benefit to administration within 3 hr window. Some evidence for extending window to 4.5 hrs
Intra-arterial thrombolytics: IA thrombolysis shown
beneficial up to 6 hrs. 2 FDA approved devices for
mechanical intracranial embolectomy (MERCI and
Penumbra). Several devices used off label
(balloons and stents) or in development
What is penumbra
Aspiration microcatheters + suction pump
