Stroke Mechanisms (Rybinnik)

Question 1

Define cerebral infarct.

Answer 1

type of ischemic stroke resulting from a blockage in the blood vessels supplying blood to the brain

Question 2

Distinguish between the mechanisms underlying ischemic and hemorrhagic stroke.

What are the differentiating clinical features.

Answer 2

Ischemic: clot within vessel stops blood flow to an area of the brain -> deprive neurons of oxygen and nutrients

Hemorrhagic: blood begins to fill brain space (mass effect)

Differentiating clinical features:

• Headache
• Lethargy
• Confusion

Question 3

Explain the contraindications of tPA in treatment of acute stroke.

Answer 3

tPA = tissue plasminogen activator (for blood clots)

• active internal bleeding
• acute intracranial hemorrhage
• recent intracranial or spinal surgery or serious head trauma

Question 4

Distinguish between the mechanisms and symptoms of lacunar and large-vessel strokes (both ischemic thrombotic stroke subtypes)

Answer 4

Lacunar (not cortex): Small-vessel subcortical lesions - body able to adjust so takes decades for clot to make an impact (circle of willis)

Large-vessel (cortex): atherosclerosis (intracranial or extra cranial i.e. middle cerebral artery)

Question 5

List the risk factors for embolic stroke.

Answer 5

Cardiac, artery to artery

VERY SEVERE/SUDDEN

Clinical features: maximal deficit at onset

risk factors:

• atrial fib (when this happens, there’s a stasis of blood in the LA -> when blood goes back to normal rhythm, that clot gets pushed up to the brain)
• cardiac tumors
• valvular disease

Question 6

Describe (generally) the most common sites for hemorrhagic strokes.

Answer 6

Basal ganglia / Thalamus (arterioles off MCA and PCA) - 50% - HTN

Lobar (penetrating branches of ACA, MCA, PCA) - 33%

Brainstem Cerebellum (Branches of basilar, PICA

Question 7

Describe the major risk factors for hemorrhagic stroke.

Answer 7

Hypertension

Question 8

Describe the features of A-V malformation.

Answer 8

Arteries and thin walled veins connected

Lack of capillaries -> therefore, no oxygen exchange

Question 9

List the signs of subarachnoid hemorrhage.

Answer 9

Severe headache (97%) - worst headache of life
Lethargy
Nausea
Vomiting

Question 10

Describe the mechanisms of venous stroke.

Answer 10

Impaired drainage causing brain swelling and damage

• Thrombosis of cerebral veins

Question 11

What is a TIA

Answer 11

Transcient ischemic attack - 10-60 min / unilateral weakness or speech disturbance w/o weakness / history of diabetes / age > 60 years

Beyond 60 min = stroke