3. Vascular Disease & Stroke Flashcards
SUDDEN onset of a focal neurological impairment due to ischemia or hemorrhage; NOT reversible; more common in older men; risk factors are DM, HTN, Smoking, Hyperlipidemia, Obesity and Sleep Apnea
Stroke
Two types of Strokes
Ischemic
Hemorrhagic *
- less common but more fatal
(Ischemic/Hemorrhagic) strokes are more common
Ischemic (~80%)
(Ischemic/Hemorrhagic) strokes are commonly caused by atherosclerosis with thrombosis in LARGE vessels and/or embolic occlusion of DISTAL vessels; can also occur due to venous thrombosis like in superior sagittal sinus (due to infection or hyper-coagulation states in pregnancy)
Ischemic
Emboli causing an ischemic stroke often originate from
EXTRA-cranial thrombi (atherosclerosis of Carotid artery bifurcation or from the heart)
What is the spectrum of consequences of brain ischemia (best to worst)
- No effect (thanks to anastomoses!)
- TIA (brief, focal neurologic deficits but reversible)
- “Incomplete” infarct (neuronal necrosis)
- “Complete” infarct (BOTH neuronal AND glial necrosis)
*neurons are more vulnerable that glial cells to ischemia
There typically no gross changes in the brain with CT until ________ HOURS after the infarct
6-8
CT findings of brain infarct (remember that it takes 6-8 hours for anything to be grossly visible)
Early (1-2 days): congestion, discoloration of grey matter
Late: cavitation (phagocytosis of dead tissue)
Histologic findings of a brain infarct
- Hours: Red (“dead”) neurons
- 24 hours: neutrophilic infiltrate
- 48 hours: Macrophage infiltrate –> discoloration of grey matter
- Weeks: Macrophage clear debris –> cavitation
(Focal/Global) ischemia is due to the occlusion of a blood vessel; infarct in local area; commonly due to…
- atherothrombosis (1 large vessel or many small vessels)
- intra-arterial (artery to artery) emboli, and
- cardiogenic emboli.
Focal (or “territorial” or “local”)
- more common than global
(Focal/Global) ischemia is due to cardiac arrest, systemic hypotension or increased ICP cutting off cerebral perfusion; causes widespread necrosis that can be accentuated or limited to watershed areas
Global (or “generalized”)
*note watershed areas (시냇물 shape)
The maximal amount of swelling after an infarct is usually within
one week
*can cause a mass lesion
Peripheral rim of “lesser” ischemia surrounding a central core of maximal ischemia
Penumbra
Consequences of Brain Infarcts
Focal neurologic deficites Cognitive impairment (Vascular dementia)
Common causes of Brain Hemorrhage
Hypertensive small-vessel disease Ruptured Berry Aneurysm Ruptured arteriovenous malformation Cerebral amyloid angiopathy Drugs/Neoplasm/Trauma
MOST common cause of Intracerebral Hemorrhage
Hypertension
Acute hypertensive hemorrhage typically occurs in what two vessels?
- Lenticulostriate vessels (branches of MCA supplying deep cerebral nuclei like putamen)
- Pontine arteries (branches of Basilar artery)
* note that they are “SMALL” vessels
Most common cause of a Subarachnoid Hemorrhage (hemorrhage that moves into CSF space b/w arachnoid and pia maters); patients often say worst HA of my life; CSF xanthochromic (bilirubin in CSF)
Ruptured Berry Aneurysms
Abnormal dilation of an artery (due to weakening of vessel wall) that arise at the base of the brain where the major blood vessels meet (“Circle of Willis”); most occurs in Anterior circulation; MOST don’t rupture but still a concern; NEVER occurs in children
Berry Aneurysm
Berry aneurysms are more likely in the (anterior/posterior) circulation of the Circle of Willis
Anterior
Mean age of Berry Aneurysm rupture (remember vast majority don’t ever rupture)
50