Lecture 66 + 68 - Stroke Pathophysiology and Treatment

Question 1

Cranial Perfusion Pressure (CPP) = _______ - ______.

As MAP decreases, capillaries compensate via constriction. However, if pressure drops too low, they collapse –> this leads to a failure of _______ pump activity –> cells can’t regulate flow of water and thus swell (Cytotoxic edema).

As MAP increases, capillaries compensate via dilation. However, if pressure increases too much, endothelial cell ______ junctions become leaky, allowing fluid to move into the brain parenchyma (NOT into the cells) –> this is called _______ edema.

Answer 1

CPP = MAP - ICP

Na/K pump

Tight junctions

Vasogenic edema

Question 2

How does autoregulation of CPP change with chronic Hypo or Hypertension?

Answer 2

The range for autoregulation of CPP will shift in accordance with the chronic physiological state. Chronic Hypotension –> Lower CPP autoregulation range.

Question 3

_______ is the term used to describe the area of a brain during ischemic stroke that is still partially perfused, while Ischemic Core describes the area that is no longer perfused at all.

Answer 3

Penumbrum

Question 4

IV TPA should be given to patients with ischemic stroke if:

• It is within _____ hrs since onset of stroke.
• BP < _____/_____
• Glucose is not low (this can mimic stroke)
• Head CT without contrast shows no bleed
• If patient is not Actively bleeding
• If patient is not AT RISK for bleeding

Answer 4

4.5 hrs since onset

BP < 185/105

Question 5

Performing Endovascular Reperfusion Therapy requires the patient meets 4 criteria:

1. Reasonable _______ function
2. Disabling _______
3. Acute Large vessel ______
4. Brain left to save

Answer 5

Reasonable Baseline Function

Disabling Deficit

Acute Large Vessel Clot

Brain Left to Save

Question 6

Determining whether or not there is “Brain left to save” differs between the first 6hrs post stroke and the time after that. Initially, and up to 6 hours, there may be Clinical-to-Imaging mismatch. What does this mean?

Answer 6

This means a CT may not show any ischemic changes, while the patient exhibits diabling neuro deficits on exam. The CT serves as a surrogate for Ischemic Core and the Diabling Deficits serve as a surrogate for Penumbra.

No ischemic changes on CT –> no ischemic core yet.

Diabling deficits –> definitely Penumbra somewhere

Question 7

If CT shows ischemic change, what can be used to determine Ischemic Core vs Penumbra?

Answer 7

CT Perfusion imaging can be used.

Ischemic core will show in pink –> indicates cerebral blood flow < 30%.

Penumbra will show in green –> Increased time for perfusion (normal is about 0.5 - 1 s)

Question 8

With Carotid stokes, a piece of the carotid plaque can break off and cause a small, focal stroke.

OR

If the Carotid gets blocked off completely –> _______ stroke in the area between the ACA and MCA.

Answer 8

Watershed

Question 9

Small vessel strokes, unlike Large vessel, will never present with ______ deficits (e.g. Aphasia, Neglect, field cuts), as they are Subcortical lesions.

Unlike with Large vessel disease in which _______ deposits in the muscle layer or the vessel wall (Atherosclerosis), ________ deposits in the vessel wall in Small vessel disease (Lipohyalinosis).

Answer 9

Cortical deficits

Cholesterol

Hyaline

Question 10

How does the course of Embolic stroke differ from Ischemic or hemorrhagic?

How does the zone of the infarct compare between Embolic and Ischemic/Hemorrhagic Stroke?

Answer 10

In Embolic stroke, there is an initial Severe deficit that improves rapidly. Ischemic and Hemorragic stokes have persistent deficits, at least until intervention.

Zone of infarct is very large for Emolic stroke OR there will be Infarcts in MULTIPLE vascular territories (multiple emolisms).

Question 11

Patients that present with acute, focal neuro deficits –> think ______ stroke. Patients that present with acute, focal neuro deficits with headache, lethargy, and confusion –> think _______ stroke.

Why?

Answer 11

Ischemic

Hemorrhagic

This is because the hemorrhage builds up quickly, causing increased ICP and mass effect and headache.

Question 12

Hemorrhagic stroke that occurs in deep brain structures results from rupture of ______ (large or small?) vessels. Hemorrhagic stroke that occurs in the cortex (lobar) can have quite a few different causes, including Vasculopathy, Arterio-venous malformation, Neoplasm, or Coagulopathy.

Keep in mind these are both Intracranial Hemorrhages

Answer 12

Small vessel

Question 13

Charcot-Bouchard Aneurysms refers to the bulging of _____ (large or small?) vessels –> rupture leads to Intracranial hemorrhagic stroke.

Answer 13

Small vessels

Question 14

In older patients with dementia that show multiple Lobar brain bleeds, the underlying cause of damage to the vessels is likely build-up of _______.

Answer 14

Amyloid

Question 15

What is significant about the location of Arteries and Veins on histology when viewing an Arteriovenous malformation?

Answer 15

They will appear right next to each other (they don’t normally).