Cerebrovascular Disease

Question 1

What are the 3 clinical criteria by which stroke is identified?
(Adams, 780)

Answer 1

1) Temporal profile of the clinical syndrome
2) Evidence of focal brain disease - characteristic of a vascular occlusion
3) Clinical setting

Question 2

Most common sites of atherothrombosis

Answer 2

1) ICA at its origin from the CCA
2) Cervical part of the vertebral arteries and at the junction to the basilar artery
3) Stem or at the main bifurcation of the MCAs

Less frequent:

4) Proximal PCAs around the midbrain
5) Proximal ACAs as they pass over the corpus callosum

Question 3

Carotid artery stenosis level to likely cause stroke in the distal arteries

Answer 3

above 90% stenosed

residual lumen of less than approx 2mm

Question 4

Risk of stroke in patients with atrial fibrillation in the following:
75 years old

Answer 4

1% per year in those less than 65; 8% per year in those more than 75% with additional risk factors

Question 5

At what thickness will atheromatous plaques in the ascending aorta cause stroke?

Answer 5

> 4mm is associated with an increased risk for embolic stroke in up to 38% of those with previously embolic stroke of unknown origin

Question 6

Migrating or traveling embolus syndrome commonly affects which arteries

Answer 6

The posterior cerebral artery;
Clinical picture: Before hemianopsia develops, the patient has transient vertigo, diplopia or dysarthria. Small residual areas of infarction may be seen in the brainstem.

Question 7

Other rare causes of cardioembolism

Answer 7

PFO
Subendocardial fibroelastosis
Idiopathic myocardial hypertrophy
Cardiac myxomas
Myocardial lesions of trichinosis

Mitral valve prolapse is no longer thought to be an important origin for embolic stroke unless there is severe ballooning of the valve (which may be seen in Ehlers Danlos)

Question 8

Pulmonary and Other Sources of Embolism

Answer 8

1) Pulmonary vein atherosclerosis
2) Osler-Weber-Rendu disease with pulmonary shunts
3) Post thyroidectomy (thrombosis in the stump of the superior thyroid artery may protrude into the lumen of the carotid artery)
4) During cerebral arteriography
5) Diffuse cerebral fat embolism - more general encephalopathy like findings -> Diffuse petechial hemorrhages (white matter)
6) Cerebral air embolism

Question 9

What findings in TIA suggest it is secondary to atherosclerosis and thrombosis? (Adams 787)

Answer 9

Brief 2-10 minute recurrent attacks of the SAME clinical pattern

Question 10

Ophthalmoscopic findings in transient monocular blindness

Answer 10

Arrest of blood flow in the retinal arteries and the breaking up of the venous columns to form a “boxcar pattern”

Question 11

Possible causes of TMB?

Answer 11

1) Platelet or fibrin emboli

2) Platelet aggregation in situ

Question 12

Exercise and Postural TIAs are suggestive of what disease?

Answer 12

Stenosis of aortic branches such as is seen in Takayasu’s arteritis (Adams, 788)

Question 13

What other conditions mimic TIAs where anticoagulation or antithrombosis may be considered harmful

Answer 13

Meningioma
Glioblastoma
Metastatic brain cancer
Subdural hematoma

Question 14

Autoregulation functions between which ranges of MAP

Answer 14

50 to 150 mmHg. Small pial vessels are able to constrict and dilate to maintain CBF.

Question 15

If the limits of autoregulation are surpassed, what disease entity develops

Answer 15

Hypertensive encephalopathy

Question 16

Cerebral blood flow rates where:

1) Marked ATP depletion, increase in extracellular K+ and intracellular Ca+, cellular acidosis
2) Infarction occurs (almost regardless of duration)
3) Hypoperfusion occurs which may lead to tissue damage
4) Glutamate release
5) Cerebral metabolic rate for glucose

Answer 16

1) 6-8 ml/100g/min
2) 10-12 ml/100g/min
3) 12-23 ml/100g/min
4) 20-30 ml/100g/min (Greenfield)
5) 25-35 ml/100g/min (Greenfield)

Question 17

What interferes with the recovery of neurons after ischemia?

Answer 17

1) Free fatty acid (phospholipase) accumulation

2) Increased intracellular calcium

Question 18

How many minutes of anoxia leads to irreversible damage?

Answer 18

30 minutes

After this, there is inability for cells to utilize glucose and manufacture protein.

Question 19

What factors reduce the cell’s tolerance to hypoxia?

Answer 19

1) Hypoglycemia
2) Hyperthermia (Decreasing core body temp by 2-3C reduces metabolic requirements and increases neuronal tolerance by 25%)

Question 20

What are the red or whitish emboli within the retina called?

Answer 20

Hollenhurst plaques

Question 21

What is the clinical picture of vertebral artery dissection?

Answer 21

1) cervicooccipital pain

2) brainstem deficits

Question 22

What vessels anastamose with the vertebral artery if it is occluded proximally?

Answer 22

Thyrocervical, deep cervical and occipital arteries

Question 23

Lacunes are caused by occlusion of small arteries of what size?

Answer 23

50 to 200 microns in diameter

Question 24

What are the 3 major mechanisms for lacunar infarction?

Answer 24

1) Fibrohyalinoid arteriolar sclerosis - involving the proximal part of the small penetrating vessels
2) Atherosclerosis of a large trunk vessel that occludes the origin of the small vessels
3) Embolism (least frequent)

Question 25

Fibrohyalinoid arteriolar sclerosis of the small penetrating vessels frequently lead to the formation of?

Answer 25

Charcot-Bouchard Aneurysms

Question 26

Where are lacunes situated?

Answer 26

In decreasing order of frequency: 1) Putamen 2) Caudate 3) Thalamus 4) Basis Pontis 5) Internal capsule 6) Deep in the central hemisphere

Question 27

What are the average size of lacunes?

Answer 27

3 to 15 mm.