Ischemic brain disease

Question 1

What is the equation for cerebral blood flow (CBF)?

Answer 1

CBF = CPP/CVR

CPP stands for cerebral perfusion pressure and CVR stands for cerebrovascular resistance.

Question 2

What happens to CBF despite variations in mean arterial pressure (MAP)?

Answer 2

CBF remains constant

This is due to autoregulation mechanisms in the brain.

Question 3

Which brain tissue has a greater CBF, gray matter or white matter?

Answer 3

Gray matter

Metabolically active sites in the brain also exhibit greater CBF.

Question 4

What is the primary cause of ischemic damage in the brain?

Answer 4

Reduction in O2 supply to tissue

This leads to loss of neuronal activity.

Question 5

What occurs as a result of energy depletion in brain cells?

Answer 5

Loss of ATP and depolarization of cell membrane

This triggers a cascade of cellular events leading to cell death.

Question 6

What type of edema results from the breakdown of cell membranes and the blood-brain barrier (BBB)?

Answer 6

Vasogenic edema

This occurs due to increased permeability of the BBB.

Question 7

Which areas of the brain are particularly vulnerable to ischemia?

Answer 7

• Occipital lobe
• Parietal lobe
• CA1 region of hippocampus
• Cerebellum
• Caudate nucleus

These areas are more sensitive to ischemic events.

Question 8

What is the ischemic penumbra?

Answer 8

Area of ischemia that is potentially salvageable

It surrounds the core of irreversible infarction.

Question 9

What imaging techniques can estimate the size of the ischemic penumbra?

Answer 9

• Diffusion-weighted imaging (DWI)
• Perfusion-weighted imaging (PWI)

DWI shows the infarct core, while PWI shows the ischemic area.

Question 10

What are the two main classifications of stroke?

Answer 10

• Hemorrhagic
• Ischemic

Strokes can also be classified by the vessel affected.

Question 11

What type of stroke is characterized by a territorial infarct?

Answer 11

Large vessel stroke

This is in contrast to small vessel (lacunar) infarcts.

Question 12

What happens to ADC values in the days following an acute arterial stroke?

Answer 12

ADC values drop for several days and remain reduced for 4-5 days before pseudonormalizing

After 10 days, ADC values become elevated.

Question 13

What is a common MRI feature of arterial strokes in the acute stage?

Answer 13

Restricted diffusion on DWI

This is typically associated with hyperintensity on DWI and low signal on ADC.

Question 14

What is the most common site of territorial infarcts in dogs?

Answer 14

Cerebellum

This site is preferentially affected in cases of arterial infarction.

Question 15

What do lacunar infarcts affect?

Answer 15

Small perforating arteries

They are typically small focal lesions located within the territory of small vessels.

Question 16

What is a differential diagnosis for arterial infarcts?

Answer 16

• Artifactual (T2 shine-through)
• Early abscessation
• Post-ictal edema
• Hypertensive encephalopathy
• Viral encephalitis

These conditions can mimic or complicate the appearance of arterial infarcts on imaging.

Question 17

What is the duration of a transient ischemic attack (TIA)?

Answer 17

Less than 24 hours

TIAs do not result in permanent infarction.

Question 18

What is the imaging appearance of global brain ischemia?

Answer 18

T2/FLAIR hyperintensity within cortical gray matter

This typically affects the parietal and occipital lobes bilaterally.

Question 19

What is a key MRI finding in hypertensive encephalopathy?

Answer 19

T2 hyperintensities within the white matter due to vasogenic edema

This condition results from failure of autoregulation of cerebral vasculature.

Question 20

What type of vascular anomalies are most commonly congenital?

Answer 20

Arteriovenous malformations

These may not be apparent until later in life.