8/26 Stroke Mechanisms - Rybinnik

Question 1

look at slides appendices!

Question 2

principles of AIS therapy

(acute ischemic stroke)

Answer 2

ask the important questions:

• last time known normal
• patient’s history
• contraindications to TPA
• head CT asap

Question 3

locations of hemorrhages

Answer 3

basal ganglia/thalamus (50%)

• lenticulostriates off MCA
• thalamogeniculates off PCA

lobar (33%)

• penetrating branches of ACA, MCA, PCA

brainstem/cerebellum (17%)

• paramedian branches of basilar
• penetrating branches of PICA, AICA, SCA

Question 4

intracerebral hemorrhage

Answer 4

subtype of hemorrhagic stroke

two subtypes: hypertensive and lobar

• hypertensive (HTN increases risk 9x)
  
  • ​small penetrating arterioles (basal ganglia, thalamus, pons, cerebellum)
• lobar
  
  • ​vascular malformations
  • tumors (METS or primary)
  • coagulopathy
  • vasculopathy (cerebral amyloid angiopathy, moya moya, vasculitis)
    
    • CAA: 60+, multiple lobar hemorrhages, amyloid deposits in leptomeningeal and cortical arterioles, assoc with dementia
  • drugs
  • trauma (frontal, occipital, temporal)

Question 5

rare causes of strokes

Answer 5

• arterial dissection: tearing in internal layers of artery wall → healing process narrows artery
• sickle cell: sickled cells damage top of carotid…over time → narrowing of ICA, “puff of smoke” collaterals (“moya moya” vessels)
  
  • hemorrhages in adults
  • ischemia in kids
• hypercoagulable states: be especially wary in younger women, miscarriages, family hx of thrombosis
• vasculitis: infl of blood vessels → fibrosis of vessel on healing
  
  • typically younger patients, headaches, cognitive decline, recurrent strokes
• vasospasm (ex. cocaine induced)
• venous sinus thrombosis
• genetics (ex. cadasil)
• complicated migraine

Question 6

embolic strokes

Answer 6

subtype of ischemic strokes

2 further subtypes: cardiac, artery-to-artery

• clinical features:
  
  • maximal deficit at onset (sudden embolus introduced! brain has NO time to adjust and get collaterally adapted)
• radiographic features:
  
  • large zone of infarct
  • infarcts in multiple fascular territories
  • dense vessel sign on CT
• embolic sources: heart STRUCTURE or heart FUNCTION
  
  • atrial fibrillation : stasis of blood in left atrium → clotting on left atrial appendage…when you restore normal rhythm, that clot gets thrown!
  • valvular disease
  • structural heart disease (dilated cardiomyopathy)
  • paradoxical embolus through PFO (unclosed foramen ovale! v rare)
  • aortic arch plaque
  • cardiac tumors

Question 7

basic overview of arterial anatomy

Answer 7

aortic arch gives off

• L carotid
• L subclavian
  
  • L vertebral
• R subclavian
  
  • R carotid
  • R vertebral

subclavians go on into arm

common carotid → internal (to brain) and external (branches in neck)

Question 8

venous infarctions

Answer 8

thrombosis of cerebral veins

• increased venous pressure: decr perfusion pressure and blood flow, incr blood volume in brain

→ recruitment of collaterals

• initially compensates

→ compensatory failure

• vasigenic edema (bbb disrupted), increase in intravascular pressure

→ parenchymal lesions

• failure of energy metabolism, venous infarct, venous hemorrhage

Question 9

stroke subtypes

Answer 9

ischemic (78%)

• thrombotic (large vessel)
• thombotic (lacunar)
• embolic (cardiac, artery to artery)
• rare causes
• cryptogenic (no idea)

hemorrhagic (22%)

• intracerebral (ICH)
• subarachnoid (SAH)

Question 10

what is TIA?

Answer 10

transient ischemic attack

brain pain

sudden focal neurologic deficit (usually weakness on one side) lasting 10-60 min

ABCD score: features of a typical TIA

• AGE: 60+
• UNILATERAL WEAKNESS or SPEECH DISTURBANCE without weaness
• DURATION: 10-60 min
• history of DIABETES

Question 11

mechanism of hematoma growth

Answer 11

1. explosion: continuous bleeding from single ruptured vessel

2. avalanche: secondary shearing of adjacent vessels

• will see presence of many small ruptured arteries in the periphery of the main hematoma

Question 12

types of stroke

Answer 12

1. ischemic: (78%) blood vessel blocks, depriving neurons of oxygen and nutrients
2. hemorrhagic: (22%) hemorrhange into brain parenchyma or subarachnoid space

• suspect hemorrhagic if you see:
  
  • headache
  • lethargy
  • confusion

Question 13

subarachnoid hemorrhage

Answer 13

subtype of hemorrhagic stroke

• clinical features
  
  • severe headache (97%)
  • meningeal signs
  • lethargy, nausea, vomiting
• complications
  
  • rebleeding (24-48hr)
  • vasospasm (7-10d)
  • hydrocephalus (>24hr)
• causes
  
  • trauma
  • saccular (berry) aneurysms at branch points in Circle of Willis
  • vascular malformations

Question 14

thrombotic strokes

Answer 14

subtype of ischemic stroke

two further subtypes:

1. thrombotic (large vessel)

• clinical features:
  
  • 40+
  • vascular risk factors
  • preceeding TIAs
• mechanism: atherosclerosis (intracranial or extracranial vessels)

2. thrombotic (lacunar)

• clinical features:
  
  • milkder symptoms
  • absence of cortical deficits! (ex. aphasia, neglect)
• radiographic features:
  
  • <1.5cm diameter lesion on MRI
  • subcortical lesions
• mechanism: lipohyalinosis, microatheromas, microembolism