Stroke Pathology

Question 1

define stroke

Answer 1

development of a focal or global neurological deficit due to a vascular events.

warnings signs:
transient clinical events may also occur due to a vascular event.
Silent vascular events may occur.

Question 2

what is the most common pathological event behind a stroke? second most? third most?

Answer 2

Infarction (75%)

Haemorrhage (25%)

Subarachnoid haemorrhage (5%) 
-more related to pathology large vessels in subarachnoid space, rather than trauam

Question 3

prevalence of stroke related mortality?

Answer 3

third leading cause of death. 10% of all deaths attributable to stroke.

Question 4

Risk factors for cerebral infarction?

Answer 4

aging, hypertension, cardiac disease (atrial fibrillation), hyperlipidaemia, diabetes mellitus, hypercoagulable states (antiphospholipid antibody syndrome), obesity, smoking

Question 5

what is a cerebral infarction?

Answer 5

necrosis of cerebral tissue in a particular vascular distribution in response to vessel occlusion or severe hypo-perfusion.
–>usually related to arterial obstruction, but may also be at level of arterioles, veins, and heart.

Question 6

mechanisms of infarction?

Answer 6

• inadequate supply of blood to tissues due to pump failure.
• inadequate supply of blood due to narrowed vessel lumen (due to atherosclerosis, thrombosis, hypertensive vessel thickening, diabetes, amyloid angiopathy).
• vessel occlusion by embolus (most common)

Question 7

what is the most common cause of infarction? and thus stroke?

Answer 7

vessel occlusion by embolus

Question 8

cardiac cause of cerebral infarction?

Answer 8

from thrombi built up in valves or recent infarct site in myocardium

Question 9

T/F - in pathogenesis of cerebral infarction, the most common cause of large and small vessel occlusion is thrombosis (not emboli).

Answer 9

TRUE. Thrombosis is much more common. Except in the posterior circulation, where emboli are more commonly the cause of occlusion.

Question 10

T/F thrombosis is the most common cause of venous occlusion leading to cerebral infarction?

Answer 10

TRUE.

Question 11

how might a probe-patent interatrial septum result in thrombosis potentially causing cerebral infarct?

Answer 11

this is a congenital condition where valve flaps have not fully fused, leaving a potential opening. 1/3 of people have this.
clot thrombotic material could pass from Rt atrium to Lt atrium in situation where right atrial pressure is raised
–>right sided thrombi could develop in the legs
—–>more likely in younger patients than older.

Question 12

what are most common sites of athersclerosis in the cerebral circulation?

Answer 12

circle of willis and associated vessels:

• basilar artery
• junction of vertebral arteries

Question 13

3 risks of atherosclerosis?

Answer 13

hypoperfusion
stenosis
thrombosis

Question 14

what gross/histological features would be present 36hrs after cerebral infarction?

Answer 14

loss of definition b/w gray and white matter; ventricles have narrowed with midline shift at falx cerebri, sulci obliteration.

nerve cell and glial nuclei would appear shrunken, pyknotic.

Question 15

what gross/histological features would be present days/weeks after cerebral infarction?

Answer 15

liquefactive necrosis

-lots of neutrophils and cellular debris

Question 16

what gross/histological features would be present months/years after cerebral infarction?

Answer 16

crater in the brain left behind, with gliosis (scarring) in the margins

Question 17

how are cerebral micro aneurysms caused?

Answer 17

hyaline arteriosclerosis of tiny vessels deep in the brain substance.
-diabetes (and other conditions) may cause these vessels to thicken, allowing thrombus to develop and causing either burst or stricture.

Question 18

what causes death following cerebral infarction?

Answer 18

infarction of brain stem (and adversely affected vital areas), 
cerebral swelling,
pneumonia,
cardiovascular disease, 
pulmonary thromboembolism

Question 19

what are possible effects of raised intracranial pressure?

Answer 19

transtentorial herniation; brainstem hemorrhages

Question 20

most common cause of intracerebral haemorrhage?

Answer 20

hypertensive small vessel disease

Question 21

what are the causes of intracerebral haemorrhage?

Answer 21

hypertensive small vessel disease, 
congophilic (amyloid) angiopathy, 
blood disorder,
tumour,
vasculitis,
vascular malformation, 
drugs

Question 22

which regions of the cerebrum are most susceptible to hypertensive haemorrhage ?

Answer 22

• basal ganglia/thalamus,
• lobar white matter,
• cerebellum,
• pons

NB: characterized by presence of small vessel disease! (hyaline arteriosclerosis)

Question 23

What are the causes of non-traumatic subarachnoid hemorrhage?

Answer 23

-Rupture of sacculur aneuryms (Berry Aneurysm)**most common

• Rupture of mycotic/atherosclerotic aneurysm
• extension of intracerebral hemorrhage (going into ventricular system and out into subdural space)

Question 24

what are the risk factors for developing a saccular/berry aneurysm

Answer 24

• being female
• aging
• polycystic kidney disease
• Type III collagen deficiency
• coarctatation of aorta
• hypertension
• smoking/alcohol

Question 25

where are saccular aneurysms most likely to occur?

Answer 25

• sites of congenital weakness at arterial bifurcations
• more likely anterior than posterior circulation

especially at:

• bifurcation of middle cerebral artery
• junction of ICA and posterior communicating artery
• anterior communicating artery

Question 26

complications of ruptured aneurysm?

Answer 26

• subarachnoid haemorrhage (+/- intraparanchymal)
• cerebral oedema and raised ICP
• vasospasm and infarction (vessels in circle of willis)
• ventricular obstruction
• hydrocephalus