Intro to Stroke Flashcards
stroke
*sudden, focal brain injury due to blood-vessel problem
*brain attack (medical emergency)
*preventable and treatable
epidemiology of stroke in the US
*affects > 800,000 persons per year
*causes 200,000 deaths per year
*5th leading cause of death in US
*leading cause of long-term disability
*costs > $70 billion per year
the stroke belt
*area of US with highest death rate due to stroke
*southern (southeast) states and pacific northwest
*cause not known
*traditional risk factors do not explain it
the stroke syndrome
*sudden acute neurological deficit
*vascular etiologies (hemorrhagic or ischemic)
infarction - definition
death of neurons, glia, and endothelium due to ischemia
hemorrhage - definition
occurs when there is bleeding into the brain parenchyma or potential intracranial space (from a blood vessel rupture)
hemorrhagic infarction - definition
occurs when there is bleeding into an area of ischemic infarction
3 stroke types
1) ischemic stroke (clot blocking artery)
2) intracranial hemorrhage (bleeding into brain)
3) subarachnoid hemorrhage (bleeding around brain)
transient ischemic attack (TIA)
*ischemic (low-blood-flow) stroke without permanent damage
*usually 20-30 minutes, most < 1 hour
*important warning of impending stroke
common stroke symptoms
*weakness or numbness, epc. 1 side of body
*difficulty speaking or understanding speech
*visual loss in one or both eyes
*severe, unusual headache
*dizziness, if associated with another symptom
*hemorrhage vs. ischemic infarct
*both present with sudden, acute deficit
*supporting evidence for hemorrhage: severe H/A at onset, younger age with h/o HTN
*CANNOT MAKE DEFINITIVE DX BETWEEN THE 2 CLINICALLY (need imaging - non-contrast head CT looking for blood)
stroke risk factors - non-modifiable
*age
*sex
*family history
stroke risk factors - medical
*HYPERTENSION
*prior stroke/TIA
*heart disease, esp a-fib
*hyperlipidemia
*diabetes
*obesity
*sickle cell disease
stroke risk factors - lifestyle
*smoking
*heavy alcohol use
*sympathomimetic drugs (legal & illegal)
*marijuana use
*sedentary lifestyle
*southern diet
common causes of ischemic (low blood flow) strokes
*atherosclerosis!!
*small artery disease
*cardioembolism (a-fib)
*hypoperfusion
*hypercoagulable states
*dissections/vasculitis
common causes of hemorrhagic (bleeding) strokes
*intracerebral: longstanding HTN and small artery rupture
*subarachnoid: trauma / ruptured berry aneurysm
primary prevention of stroke
identify and control/treat risk factors (HTN, DM, hyperlipidemia, smoking, sickle cell, carotid stenosis, obesity)
secondary prevention of stroke
- identify cause of stroke
- take appropriate action (meds, surgery) and initiate appropriate anti-thrombotic therapy
- identify and treat all risk factors
emergency stroke care
“the 7 D’s”:
-detection of onset of stroke signs and symptoms
-dispatch through activation of the EMS system and prompt EMS response
-delivery of the victim to the receiving hospital
-door (ED triage)
-data (ED evaluation, including CT scan)
-decision about potential therapies
-drug therapy
t-PA for stroke treatment
*thrombolysis with t-PA available for patients with ischemic stroke
*tPA does NOT save lives - it decreases the RISK OF DISABILITY
*MUST be given with 4.5 hours of stroke onset (last known normal)
*can cause dangerous bleeding if given outside the time window
penumbra
*zone of reversible ischemia around core of irreversible infarction
*salvageable within the first few hours after ischemic stroke onset
*damaged by: hypoperfusion, hyperglycemia, fever, seizure
mechanism of thrombolytic therapy (ex. tPA)
*disruption of an acute thrombus may allow restoration of blood flow into penumbra cells (revascularization and reperfusion)
*reperfusion cannot help the patient if the brain downstream is already dead
thrombus formation - overview
*fibrinogen -> fibrin (red cells and platelets adhere to fibrin strands; activated factor XIII stabilizes the clot)
*plasminogen -> plasmin (plasminogen activators, like tPA, are upregulated by binding to fibrin, making their activity “clot-specific”; plasmin degrades fibrin)
tPA criteria
*time < 4.5 hours (from last known normal)
*pressure < 185/110
*any other contraindications (already anticoagulated; bleeding contraindications; seizure or trauma; blood sugar low; recent surgery or arterial stick in non-compressible site)
endovascular therapy for stroke
*example = thrombectomy
*clot retrieval or mechanical disruption with stent retriever devices work best
*used for proximal, large artery occlusions
*within 24 hours, IF perfusion imaging demonstrates salvageable penumbra
acute stroke treatment - overview
*only ACUTE stroke treatments are tPA and endovascular therapy (heparin is not an acute stroke treatment, it is an anticoagulant; does NOT dissolve a clot that is already there)
general principles of stroke evaluation
*do NOT ASSUME etiology
*identify cause based upon stroke syndrome and lab confirmation (clinical stroke syndrome, imaging characteristics, risk factors, and lab correlates)
imaging for stroke
*brain imaging (CT head, MRI)
*arterial imaging (CTA, MRA, ultrasound)
*cardiac imaging (TEE, EEE)
antiplatelet agents
MOA: inhibition of platelet activation and aggregation
*aspirin (inhibits COX)
*clopidogrel & ticagrelor (block P2Y12 ADP receptors)
*dipyridamole & cilostazole (increases plasma adenosine & inhibits platelet phosphodiesterase)
anticoagulant agents
*warfarin (depletes Vit K dependent clotting factors - II, VII, IX, and X and protein C)
*dabigatran (direct thrombin inhibitor)
*apixaban, ribaroxaban (oral factor Xa inhibitors)
mechanism of action of warfarin
depletes Vit K dependent clotting factors - II, VII, IX, and X and protein C
when to use anticoagulants
**cardioembolic sources (A-FIB; mechanical valves; severe cardiomyopathy; patent foramen ovale)
*hypercoagulable states (such as protein S deficiency)
*venous infarction (sagittal sinus thrombosis)
when to use anti-platelet agents
*atherosclerotic disease
*small artery disease
*any ischemic stroke patient without an identified need for anticoagulation
algorithm for stroke treatment
- pt presents with acute ischemic stroke
- determine eligibility for treatment with tPA and/or endovascular therapy and treat if eligible
- acutely, all stroke patients need some form of antithrombotic therapy with at least aspirin (note: NO antithrombotics for 24 hrs if patient receives tPA)
- early statin therapy
- DVT prophylaxis
facial droop - forehead spared
UMN problem (brain)
facial droop - forehead included in paralysis
LMN problem (facial nerve)
Bell’s Palsy
facial paralysis; forehead included in the paralysis; LMN lesion of CN VII (facial nerve)
