(27A) Ischemic Stroke

Question 1

Difference between stroke, TIA, and RIND

Answer 1

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

Question 2

Hemorrhagic or ischemic stroke more common?

Answer 2

ischemic (83% vs 17%)

Question 3

4 main causes of ischemic strokes

Answer 3

1. artherosclerotic occlusion
2. embolism
3. Lacunae (dz that occludes small arterioles)
4. Cryptogenic (= unknown)

Question 4

modifiable risk factors for stroke

Answer 4

male, > 55, african american, FH

Question 5

Modifiable risk factors for stroke

Answer 5

SHODDY + Afib + carotid artery stenosis 
smoking
HTN
obesity 
DM
DYslipidemia 

**HTN is the # 1 RF but afib has the highest relative risk

Question 6

What accelerates and worsens stroke brain injury? Why

Answer 6

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

Question 7

clinically relevant aspect that differentiates ischemic core tissue vs penumbra

Answer 7

core suffers irreversible injury in <1 hr and pemubra ~4-6 hrs

Question 8

CBF =

Answer 8

CBF = MAP / CVR

Question 9

CBF will not change between MAP of ____ and ____. Significance?

Answer 9

55 - 150 mmHg; CBF will not change with changes in body position

Question 10

How does HTN affect CBF autoregulation? Clinical significance?

Answer 10

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)

Question 11

MAP above 150 mmHg leads to a condition known as

Answer 11

hypertensive enchephalopathy

Question 12

What CBF is the threshold for infarction? normal CBF?

Answer 12

20 ml/100g/min vs 55ml/100g/min

Question 13

anterior circulation strokes invovle what arteries

Answer 13

ACA, MCA, ICA and any of their branches

Question 14

small penetrating branches of MCA that go into the putamen and globus pallitus

Answer 14

lenticulostriate arteries

Question 15

presentation of ACA stroke

Answer 15

contralateral motor and sensory deficits in lower limb + frontal lobe behavior abnormalities

Question 16

presentation of superior branch MCA stroke

Answer 16

contralateral motor and sensory deficits in upper limb and face + Broca’s (non-fluent) aphasia

Question 17

presentation of inferior branch MCA stroke

Answer 17

Wernicke’s (fluent) aphasia if in dominant hemisphere and hemineglect if in non-dominant

absent motor findings

Question 18

presentation of stroke in lenticulostriate arteries

Answer 18

contralateral motor hemiparesjs

**common site of lacuna infarct secondary to unmanaged HTN

Question 19

presentation of stroke in PCA

Answer 19

contralateral homologous hemianopia (macular sparing)

larger infarcts with thalamus and internal capsule involvement my cause contrlateral hemisensory loss and hemiparalysis

Question 20

What are the common sites of atherlosclerotic plaques

Answer 20

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

Question 21

pathogenesis/etiology of lacunar strokes

Answer 21

microartheroma (~artherothrombosis)
microemboli (from proximal vessels or heart–post MI, afib, valvular heart disease)
lipohyalinosis
fibrinoid necrosis (from chronic HTN)

Question 22

What are the common causes of cardiogenic emboli

Answer 22

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)

Question 23

How is CNS vasculitis differentiated from other etiologies of ischemic stroke?

Answer 23

vasculitis is MULTIFOCAL – see segmental narrowing with multiple occlusions

Question 24

What types of vasculitis wil affect the vessels in the CNS?

Answer 24

lupus, giant cell arteritis, infectious vasculitis (syphillis, lyme, AIDS, zoster, hep B), Hypersensitivity vasculitis, wegener’s, bechet’s

Question 25

what heme disorders can cause ischemic stroke?

Answer 25

hyperviscosity syndrome (multiple myeloma, polycythemia)
hypercoag state
sickle cell

Question 26

What drugs are assc with ischemic strokes

Answer 26

cocaine, LSD, amphetamine, ETOH, OCPs

Question 27

Cause of ischemic stroke secondary to trauma

Answer 27

carotid or vertebral artery dissection