41 - Stroke

Question 1

Definition of stroke

Answer 1

Development of a focal or global neurologic deficit related to a vascular event
Can be transient (transient ischaemic attack)
Can be ‘silent’ (not immediately apparent, EG cerebellar infarct manifesting as brief dizzy spells)

Question 2

Pathologic processes involved in stroke
1
2
3

Answer 2

•INFARCTION— 75%
•(Death of tissue due to inadequate blood supply)
•HAEMORRHAGE— 20%
•(tissue injury due to escape of blood from vessel/s)
•SUBARACHNOID HAEMORRHAGE— 5%
(Escape of blood primarily into the subarachnoid space. Not related to trauma)

Question 3

Number of Australian deaths attributable to stroke

Answer 3

~10% of all deaths.
Third leading cause of death.
Significant morbidity in survivors

Question 4

Risk factors for cerebral infarction

1 - 8

Answer 4

• AGING
• HYPERTENSION
• CARDIAC DISEASE [eg atrial fibrillation]
• HYPERLIPIDAEMIA
• DIABETES MELLITUS
• HYPERCOAGULABLE STATES eg antiphospholipid antibody syndrome
• SMOKING
• OBESITY

Question 5

Most common cause of cerebral infarction

Answer 5

Arterial obstruction.

Question 6

Ways in which cerebral vessels can narrow

Answer 6

Atherosclerosis
Thrombosis
Hypertensive vessel thickening, diabetes,
Amyloid angiopathy (small vessel disease, can cause either obstruction or rupture)

Question 7

Most common cause of cerebral arterial blockage

Answer 7

Embolus

Question 8

Main source of emboli for anterior cerebral arteries

Answer 8

Cardiac emboli

Question 9

Main source of emboli for posterior cerebral arteries

Answer 9

In situ emboli

Question 10

Pathology state where cardiac emboli can be generated

Answer 10

Valve vegetations in bacterial or non-bacterial thrombotic endocarditis

Question 11

Structural defect in heart that can increase risk of cardiac emboli

Answer 11

Probe-patent interatrial septum.
Increases risk of an embolus passing from right to left atrium during raised right atrial pressure (EG: a thrombus formed in legs, EG DVT).
In ~1/3 people.

Question 12

Common sites of atherosclerosis in the Circle of Willis

Answer 12

Internal carotids.
Vertebral arteries.
Basilar artery.

Question 13

Surgery for removing atheroscleroses

Answer 13

Endarterectomy

Question 14

Why does the brain swell after infarction?

Answer 14

Cytotoxic oedema (main source of oedema) 
Vasogenic oedema (where there is still a blood supply).

Question 15

Appearance of a 36-hour brain infarction

Answer 15

No difference in gross and microscopic appearance of cerebral tissue.
Swelling (can lead to subfalcine, tentorial herniations)

Question 16

Appearance of a brain infarct after days-weeks

Answer 16

Macrophages, etc infiltrate tissue, begin phagocytosing dead tissue
Process of liquefaction
Swelling decreases a lot.

Question 17

Appearance of a brain infarct after months-years

Answer 17

Gliosis (not fibrosis).

Hole where the necrosis was

Question 18

What often happens with embolic cerebral infarcts?

Answer 18

Become haemorrhagic

Can also occur with venous obstruction.

Question 19

Pathology of small cerebral vessels that can lead to thrombosis, aneurysm, bursting.

Answer 19

Hyaline arteriolosclerosis

Question 20

Type of aneurysm caused by hyaline arteriolosclerosis

Answer 20

Microaneurysms deep within brain

Question 21

Lacunar infarctions

Answer 21

Small infarctions in brain, often from small-vessel blockage

Question 22

Causes of death in people with cerebral infarction 
1
2
3
4
5

Answer 22

• Involvement of vital centres
• Cerebral swelling
• Pneumonia (from being immobilised, EG from damage to motor centres)
• Cardiovascular disease
• Pulmonary thromboembolism

Question 23

False localising sign

Answer 23

Where there is swelling in one area (EG from subfalcine, transtentorial herniations), and because this compresses the contralateral part of the brain, can make it appear that both parts of brain have been lesioned.

Question 24

Causes of intracranial haemorrhage
1
2
3
4
5
6
7

Answer 24

• Hypertensive small vessel disease
• Amyloid angiopathy
• Blood disorders
• Tumour
• Vasculitis
• Vascular malformation
• Drugs

Question 25

Characteristic of hypertensive haemorrhage (cerebral)

Answer 25

Small vessel disease (hyaline arteriolosclerosis)

Question 26

Why is acute cerebellar hypertensive haemorrhage an acute surgical emergency?

Answer 26

Can put pressure on 4th ventricle, close it, and dramatically increase ICP

Question 27

``` Particular sites of hypertensive cerebral haemorrhage 1 2 3 4 ```

Answer 27

Basal ganglia/thalamus Lobar white matter Cerebellum Pons

Question 28

Cerebral amyloid angiopathy 1 2 3

Answer 28

1) Deposition of amyloid beta in walls of superficial supratentorial blood vessels 2) Associated with superficial haemorrhages, often multiple (as more likely to survive more superficial haemorrhages) 3) Association with Alzheimer's disease

Question 29

Disease affecting deep blood vessels in brain

Answer 29

Hypertension

Question 30

Disease affecting superficial blood vessels in brain

Answer 30

Cerebral amyloid angiopathy

Question 31

Histological appearance of amyloid angiopathy

Answer 31

Looks very similar to hyaline arteriolosclerosis with H/E stain. Will be located superficially, whereas hyaline is deeper. Need to stain for amyloid.

Question 32

Causes of non-traumatic sub-arachnoid haemorrhage 1 2 3

Answer 32

1) Rupture of saccular (Berry) aneurysm (most common cause) 2) Rupture of other types of aneurysm (mycotic (infective), atherosclerotic) 3) Extension of intracerebral haemorrhage

Question 33

``` Risk factors for saccular aneurysms 1 2 3 4 5 ```

Answer 33

1) Female 2) Increased age 3) Polycystic kidney disaese 4) Coarctation of aorta 5) Hypertension

Question 34

Where do saccular aneurysms occur?

Answer 34

Sites of congenital weakness at arterial bifurcations. | In anterior circulation much more than posterior

Question 35

Three common sites of saccular aneurysm

Answer 35

1) Middle cerebral artery bifurcation/trifurcation 2) Junction of internal carotid and anterior communicating arteries 3) Distal anterior communicating artery complex

Question 36

``` Complications of aneurysm rupture 1 2 3 4 ```

Answer 36

1) Subarachnoid haemorrhage 2) Cerebral oedema, increased ICP 3) Vasospasm leading to infarction 4) Ventricular obstruction leading to hydrocephalus

Question 37

What leads to vasospasm, leading to infarction?

Answer 37

Bursting of aneurysm leads to vasospasm