Stroke 1/12/15 Flashcards
Stroke Risk Factors
- Untreated AFib
- Hypertension
- Smoking
- Hyperlipidemia
- Diabetes Mellitus
- TIA (Transient Ischemic Attack)
- Previous Stroke
- Heavy alcohol consumption
Transient Ischemic Attack (TIA)
- Common causes: embolism & stenosis-related hypoperfusion
- Examine arterial supply, cardiac, and hypercoaguable state
Stroke can be characterized as:
- Ischemic (88%)
2. Hemorrhagic (12%)
Causes of ischemic stroke
- Arteriosclerotic (large vessels)
- Embolic (24% of all strokes, affects medium vessels)
- Lacunar (small vessels)
- Amyloid deposits (microcirculation)
- Hypoperfusion (border zone)
Anterior circulation
- Middle cerebral
- Anterior cerebral
- Posterior communicating
Posterior circulation
- Includes PICA, anterior and posterior spinal arteries off vertebral
- All branches off basilar
- Posterior cerebral artery
Conditions that influence progression and extent of ischemic injury
- Rate and duration - fast onset & long duration is worse
- Collateral circulation
- Systemic circulation - want adequate systemic BP to maintain circulation
- Coagulation - hypercoaguable state increases progression and extent, exacerbating vascular occlusion
- Temperature - increased body temp is associated with greater ischemic injury
- Glucose - hyper and hypoglycemia have negative effects of ischemic injury
Normal cerebral blood flow (CBF)
50 to 60 ml/100gm/minute
Penumbra
- Electrical silence and synaptic activity greatly diminished to preserve energy stores
- Reversible
- CBF reduced to below 20 ml/100gm/minute (which is 25-50% of normal)
- “Window of opportunity”
Ischemic Core
- Irreversible neuronal injury with CBF less than 10 ml/100gm/minute
Causes of cell death
- Noxious metabolites from injured neurons
- Breakdown of blood brain barrier
- Excitotoxicity
- Apoptosis
Factors associated with red infarcts/hemorrhagic transformation of stroke
- Size of infarct
- Richness of collateral circulation
- Use of anticoagulants and interventional therapy with thrombolytic agents
Large vessel disease
- Most common disease process: arteriosclerosis
- Mostly occurs at bifurcation of vessels
- Not a significant blockage until > 70%
Medium vessel disease
- Most common pathology: embolism
- Most common cause: Afib
- Can affect proximal (more devastating impairments) or more distal part of vessels
Small vessel disease
- Most common pathology: Lacunar
- Can affect penetrating vessels & distal small vessels that usually affects deep white matter area (including internal capsule)
Microvessel disease
- Most common pathology: Amyloid deposits in arterioles and capillaries
- Commonly present in patients with dementia or Alzheimer’s
Treatment of ischemic stroke
- tPA
- Stents
- Intra-arterial clot retrieval
Types of aneurysms
- Berry - congenital weakness of vessel wall at branching points
- Charcot Bouchard - found on penetrating vessels (inside brain)
Subarachnoid Hemorrhage
- Cerebral artery on the surface of the brain
- WHOL - worst headache of my life
- Can either clip or coil
- Evaluate using clinical scales - Hunt & Hess (based on symptoms and function) OR Fischer (based on imaging)
Intraparenchymal Hemorrhage
- Bleed into substance of brain
- Direct contact of brain with blood causes secondary damage
A-V Malformation
- Direct contact between arteriole and venule
- Risk for hemorrhage because of increased pressure on veins
Dissecting aneurysms
- Results from trauma to vessel wall
- Bleeding occurs between layers of arterial wall
- Resulting space occupying clot occludes lumen of vessel
