(27A) Ischemic Stroke Flashcards
Difference between stroke, TIA, and RIND
stroke = abrupt onset of focal neurologic deficits that may be irreversible (leads to permanent deficits)
TIA = abrupt onset of focal neurologic deficits that resolve in < 1 hr and the deficits may be reversible (usually? don’t show changes on MRI)
RIND = abrupt onset of focal neurologic deficits that take LONGER THAN 1 HR to resolve + MRI that shows evidence of focal brain damage
Hemorrhagic or ischemic stroke more common?
ischemic (83% vs 17%)
4 main causes of ischemic strokes
- artherosclerotic occlusion
- embolism
- Lacunae (dz that occludes small arterioles)
- Cryptogenic (= unknown)
modifiable risk factors for stroke
male, > 55, african american, FH
Modifiable risk factors for stroke
SHODDY + Afib + carotid artery stenosis smoking HTN obesity DM DYslipidemia
**HTN is the # 1 RF but afib has the highest relative risk
What accelerates and worsens stroke brain injury? Why
hyperthermia and hyperglycemia
ischemic neurons undergo glycolysis/anaerobic respiration which causes a build-up of lactic acid, which damages neurons when it builds up
inc temp speeds up the glycolytic process and hyperglycemia increases the substrate for the accumulation of lactic acid
clinically relevant aspect that differentiates ischemic core tissue vs penumbra
core suffers irreversible injury in <1 hr and pemubra ~4-6 hrs
CBF =
CBF = MAP / CVR
CBF will not change between MAP of ____ and ____. Significance?
55 - 150 mmHg; CBF will not change with changes in body position
How does HTN affect CBF autoregulation? Clinical significance?
shifts curve to the RT = MAP plateau has a higher set point
significange = they will have dec CBF at 75 mmHg (instead of 50) therefore you must be careful not to acutely lower BP too low (into levels that would be normal for a healthy indiv)
MAP above 150 mmHg leads to a condition known as
hypertensive enchephalopathy
What CBF is the threshold for infarction? normal CBF?
20 ml/100g/min vs 55ml/100g/min
anterior circulation strokes invovle what arteries
ACA, MCA, ICA and any of their branches
small penetrating branches of MCA that go into the putamen and globus pallitus
lenticulostriate arteries
presentation of ACA stroke
contralateral motor and sensory deficits in lower limb + frontal lobe behavior abnormalities
presentation of superior branch MCA stroke
contralateral motor and sensory deficits in upper limb and face + Broca’s (non-fluent) aphasia
presentation of inferior branch MCA stroke
Wernicke’s (fluent) aphasia if in dominant hemisphere and hemineglect if in non-dominant
absent motor findings
presentation of stroke in lenticulostriate arteries
contralateral motor hemiparesjs
**common site of lacuna infarct secondary to unmanaged HTN
presentation of stroke in PCA
contralateral homologous hemianopia (macular sparing)
larger infarcts with thalamus and internal capsule involvement my cause contrlateral hemisensory loss and hemiparalysis
What are the common sites of atherlosclerotic plaques
origins of carotid and vertebral arteries bifrication of carotid ICA at carotid siphon ICA branch pts of ACA and MCA M1 segment of MCA Basilar Artery
pathogenesis/etiology of lacunar strokes
microartheroma (~artherothrombosis)
microemboli (from proximal vessels or heart–post MI, afib, valvular heart disease)
lipohyalinosis
fibrinoid necrosis (from chronic HTN)
What are the common causes of cardiogenic emboli
afib
valvular heart dz (mitral stenosis, bacterial endocarditis, prosthetic valves)
mural thrombosis post MI
**less common = atrial myxoma, mitral valve prolapse, non-bacterial endocarditis (cancer or lupus), paradoxal embolus (DVT that bypasses lungs through VSD or patent foramen ovale)
How is CNS vasculitis differentiated from other etiologies of ischemic stroke?
vasculitis is MULTIFOCAL – see segmental narrowing with multiple occlusions
What types of vasculitis wil affect the vessels in the CNS?
lupus, giant cell arteritis, infectious vasculitis (syphillis, lyme, AIDS, zoster, hep B), Hypersensitivity vasculitis, wegener’s, bechet’s
what heme disorders can cause ischemic stroke?
hyperviscosity syndrome (multiple myeloma, polycythemia)
hypercoag state
sickle cell
What drugs are assc with ischemic strokes
cocaine, LSD, amphetamine, ETOH, OCPs
Cause of ischemic stroke secondary to trauma
carotid or vertebral artery dissection
