L6- CVAs

Question 1

list the types of strokes

Answer 1

1) Ischemia: thrombotic or embolic
2) Hemorrhagic: vascular rupture; intracerebral or subarachnoid

both –> (3) Hypoxic: global or focal
all –> infarction

Question 2

how is imaging used in the diagnosis of stroke

Answer 2

CT (preferred- quicker) or MRI
1) Ischemic Stroke: lesion seen w/in hrs on MRI, appears negative w/in 24hrs on CT

2) Hemorrhagic Stroke: lesion appears immediately after onset

So in ED w/ stroke sxs –> imaging (CT) –> neg will r/o hemorrhagic

Question 3

list some general causes of functional hypoxia in the brain

Answer 3

• low partial pressure: high altitude
• toxins: cyanide
• dec O2 carrying capacity: anemia

Question 4

ischemia in the brain occurs in (transient/permanent) fashion due to (2) or (3)

Answer 4

(hypoperfusion)
1- either
2- low BP
3- vascular obstruction

Question 5

Global Cerebral Ischemia:

• (1) cause
• (2) factors affected outcome
• (3) are the outcomes

Answer 5

1- severe systemic hypotension (MI, shock)

2- severity, duration (rapid, slow), cell type involved

3- widespread neuron death –> severe neurological impairment OR death

Question 6

describe the susceptibility of different brain cells to ischemia

Answer 6

neurons more than glial cells

-pyramidal cells, Purkinjee cells

Question 7

______ are the most susceptible brain cells to ischemia (include location)

Answer 7

Pyramidal cells: hippocampus, neocortex
Purkinjee cells: cerebellum
(only mild ischemia is sufficient to cause severe damage)

Question 8

In (1) ischemia, only the affected area supplied by the vessel is damaged, and (2) is very important in limiting this damage

Answer 8

1- focal cerebral ischemia

2- collateral blood supply

Question 9

______ area has the greatest risk of a watershed infarction

Answer 9

border zone between ACA and MCA

Question 10

Watershed infarctions occur more in (global/focal) cerebral ischemia, commonly after (2) events occur. The damage produces a (3) appearance, commonly in (4) location.

Answer 10

1- global
2- hypotensive episodes
3- sickle-shaped band necrosis over cerebral convexity
4- few cms lateral to interhemispheric fissure (for ACA/MCA zone)

Question 11

what are the types of CVAs due to ischemia, indicate which is more common

Answer 11

• Embolic (more common)

- Thrombolytic

Question 12

embolic ischemic CVA:

• (1) source
• (2) risk factors (pre-disposing conditions)

Answer 12

1- cardiac mural thrombus, carotid atheromatous plaque

2- AFib, valvular disease, myocardial dysfunction

Question 13

define paradoxical emboli

Answer 13

venous emboli crosses over to arterial side (bypassing lungs to cause PE) via R –> L shunt (ASD, VSD, patent foramen ovale) leading to ischemia (legs or stroke)

Question 14

thrombotic occlusion ischemic CVA:

• (1) definition
• (2) list the possible progressions

Answer 14

1- thrombus superimposed on atherosclerotic plaque

2:

• can have anterograde extension
• can fragment / embolize
• can lead to Small Lacunar infarcts

Question 15

define small lacunar infarcts

Answer 15

• via thrombotic occlusion ischemic CVA

- -> occlusion of penetrating arteries via HTN

Question 16

describe the gross morphology of ischemia of the brain

Answer 16

• swollen brain: wide gyri, narrowed sulci
• poor demarcation between white/gray matter
• liquefied tissue => fluid filled cavity

Question 17

Histological changes of brain ischemia: 12-24hrs

Answer 17

• cytoplasmic eosinophilia
• nuclear death
• neutrophil infiltration (begins at lesion edges, where vascular supply is intact)

Question 18

Histological changes of brain ischemia: 1day-2wks

Answer 18

• tissue necrosis (liquefactive)
• macrophage influx (surrounds gliosis)
• vascular proliferation
• reactive gliosis (hypertrophied cells)

Question 19

Histological changes of brain ischemia: >2wks

Answer 19

• removal of necrotic tissue

- residual gliosis (hypertrophied cells)

Question 20

list the classifications of intracranial hemorrhages leading to stroke

Answer 20

• Intraparenchymal hemorrhages (w/in brain): hypertensive (most cases) or non-hypertensive
• subarachnoid hemorrhage

Question 21

Primary Intraparenchymal hemorrhage = (1):

• (2) mechanism of hemorrhage
• (3) clinical features

Answer 21

1- hypertensive hemorrhage
2- HTN –> small intraparenchymal vessel rupture
3- based on size and location: small = silent, large = apparent, if extended to ventricles = death

Question 22

Hypertensive Intraparenchymal hemorrhage usually occurs in the following locations….

Answer 22

basal ganglia*, thalamus, pons, cerebellum

Question 23

HTN can cause (1) morphological change in the brain of (2) vessels, mostly in (3) parts of the brain. (2) are then weakened, causing (4- two names) to occur, leaving (2) at risk for (5).

Answer 23

1- hyaline arteriolar sclerosis
2- deep penetrating arteries / arterioles
3- basal ganglia*, brainstem, hemospheric white matter
4- small microaneurysm / Charcot-Bouchard aneursym
5- rupture

Question 24

define Charcot-Bouchard aneurysm

Answer 24

small microaneurysm resulting from weakened vessels walls of penetrating cerebral arteries and arterioles due to hyaline arteriolar sclerosis

Question 25

describe the possible pathological outcomes of hypertensive cerebral arteries besides rupture --> hemorrhagic stroke

Answer 25

1) slit hemorrhages: rupture of small caliber penetrating vessels 2) lacunar infarcts: cavitary infarcts secondary to thrombosis of vessel w/ arteriolosclerosis changes of single penetrating branch 3) acute hypertensive encephalopathy: sustained inc in diastolic BP (>130) --> global cerebral dysfunction (varied Sxs)

Question 26

Non-hypertensive cerebral hemorrhages: - (1) describes location - (2) causes, hint- 5

Answer 26

1- lobar, limited to affected lobe 2: - coagulopathy - vascular malformation - amyloid angiopathy - cortical vein OR dural sinus thrombosis - tumor hemorrhage

Question 27

Of all the non-hypertensive cerebral hemorrhages, (1) has the greatest potential for hemorrhage because of (2) changes in blood distribution. (2) also leads to possibility of causing (3) overall in the body. Treatment includes (4).

Answer 27

1- vascular / arteriovenous malformation 2- high flow channels w/o arterial structure --> shunts blood away 3- high output CHF 4- excision, endovascular occlusion

Question 28

_____ is a non-hypertensive cerebral hemorrhage with a similar mechanism as hypertensive hemorrhages

Answer 28

Amyloid angiopathy: amyloid deposition --> weakens vessel wall --> risk of rupture and hemorrhage

Question 29

Subarachnoid hemorrhage: - (1) cause (include location) - (2) and (3) are conditions with high risk of (1)

Answer 29

1- rupture of saccular / berry aneurysms at branch points in the Circle of Willis 2- AD PCK 3- Ehler-Danlos syndrome

Question 30

describe the progression and location distribution of berry aneurysms

Answer 30

-not present at birth --> develop over time due to defect in tunica media - 90% in anterior circulation - 40% at ACA, 34% at MCA, 20% at int. carotid, 4% at basilar art.

Question 31

Berry Aneurysm: - (1) appearance - they are lined by (2) with (3) importantly missing - (4) is most common site of rupture on aneurysm - blood from rupture will enter (5)

Answer 31

1- saccular aneurysm, thin walled outpouching of artery 2- thickened hyalinized intima (maybe some continuous tunica adventitia) 3- muscular wall (muscularis), IEL 4- apex 5- subarachnoid space

Question 32

Berry aneurysms will rupture in response to....

Answer 32

acute inc in ICP: straining at stool, organism

Question 33

list the clinical features of Subarachnoid hemorrhage

Answer 33

- worst HA of life, 'thunderclap HA' | - Meningismus (features of meningitis due to irritation of meninges): neck stiffness, photophobia, etc

Question 34

Subarachnoid hemorrhage: - (1) prognosis - (2) investigations w/ results

Answer 34

1- poor, high mortality and worsens with successive bleeds 2- CT scan /// lumbar puncture: RBCs present, xanthochromia (yellowing of CSF due to bilirubin)

Question 35

list the complications of subarachnoid hemorrhages

Answer 35

Rebleed- common, inc risk of mortality Vasospasm- early period of hemorrhage Hydrocephalus: via healing and meningeal fibrosis --> obstructs CSF flow OR absorption

Question 36

list the vascular malformations of the brain

Answer 36

arteriovenous malformation cavernous malformation capillary telangiectasias venous angiomas

Question 37

(1) is the most common vascular malformation in the brain, affecting (fe-/males) more in the (3) age range.

Answer 37

1- AV malformation (arteriovenous) 2- males 2x 3- 10-30 y/o

Question 38

gross appearance of AV malformation

Answer 38

appears like tangled network of wormlike vascular channel

Question 39

microscopic appearance of AV malformation

Answer 39

enlarged BV separated by gliotic tissue often evidence of previous hemorrhage

Question 40

describe the clinical features / complications of AV malformations

Answer 40

seizure, intracerebral hemorrhage, OR subarachnoid hemorrhage Newborn: possibly high output CHF (blood shunting from arteries to veins)