Cerebrovascular Disease

Question 1

What is stroke?

Answer 1

brain disease due to vascular pathology
> thrombosis, embolism or hypotension causing ischaemia/hypoxia
> haemorrhage causing disruption

Question 2

Strokes are commonly associated with which conditions?

Answer 2

1. atheroma
2. diabetes
3. hypertension

Question 3

What is an infarction?
Causes?

Answer 3

critical reduction in arterial oxygenation
1. thrombotic (overall 80%+ of all strokes)
2. Embolic (atheroma, fat, air, mural)
3. hypotensive

Question 4

What is a haemorrhagic stroke?
Types?

Answer 4

a condition where ruptured blood vessels cause bleeding in the brain
1. intracerebral
2. subarachnoid

Question 5

What may cause hypoxia in the brain?
Type of damage caused?

Answer 5

1. major fall in BP or systemic hypoxia
   > causing diffuse damage
2. vessel blockage
   > causing focal damage

Question 6

Describe diffuse hypoxic damage?
Location?
Pathology?
Symptoms?

Answer 6

depends on severity and duration of hypoxia
1. Location
most susceptible neurons are in hippocampus, Purkinje cells, cerebral cortex
2. Pathology
affected brain is oedematous, raising ICP
3. Symptoms
- causes anything from mild confusion through PVS (persistent vegetative state) to immediate brain death
- acute hypotension, may also cause focal damage
> “watershed” (border zone) infarcts – most often between anterior cerebral and middle cerebral artery supplies

Question 7

Describe focal hypoxic damage?
Location?
Cause?
Symptoms?

Answer 7

1. Location
   results depend on presence of collaterals
   - some exist on surface, e.g. Circle of Willis but not within brain
2. Cause
   caused by focal vascular abnormality from thrombosis or embolism
3. Symptoms
   clinical effects depends on: site, extent and speed of onset of vascular block

Question 8

What are the thrombotic causes of focal hypoxia?

Answer 8

atheroma - commoner in DM and HTN
> usually thrombosis at carotid bifurcation, origin of middle cerebral artery or in basilar artery

Question 9

What are the embolic causes of focal hypoxia?
(Hint: clots)

Answer 9

1. cardiac mural thrombi
   > MI, valvular disease, atrial fibrillation
2. arterial thromboemboli
   > especially from carotid plaques (sometimes include plaque material)
3. paradoxical emboli - children with cardiac anomalies
4. emboli of other material (tumour, fat, marrow, air)

Question 10

Which artery is most affected by cerebral emboli?

Answer 10

middle cerebral artery territory most often affected
> emboli lodge at branches or stenoses
Note: often, occlusion cannot be identified post mortem > thromboemboli already lysed

Question 11

Describe the different types of cerebral emboli and how they come to be?

Answer 11

1. “shower” embolism of fat > occur after fractures
   > capillary blockages – disturb higher cortical function and consciousness, often with no localizing signs
2. bone marrow embolism > after trauma
   > widespread haemorrhagic lesions of white matter
3. tumour emboli
   > may also cause of hypoxia

Question 12

Describe cerebral infarcts?
Types?

Answer 12

• sometimes classified as “red” or “pale”
  > depends on presence or absence of haemorrhage from infarcted vessels
• any infarct may show surrounding zone of lesser hypoxic damage and hyperaemic reaction, which may be oedematous

Question 13

Describe venous cerebral infarcts?
Causes?
Location?

Answer 13

– usually beside sinuses
– associated with:
1. infection
2. dehydration
3. drugs (especially oral contraceptives)

Question 14

Describe the clinical presentation of a stroke caused by a cerebral infarction?

Answer 14

slowly evolving signs and symptoms
> 30 day mortality = 15-45%

Question 15

Describe the pathogenesis of stroke caused by cerebral infarction?

Answer 15

1. Cerebral hypoperfusion
2. Embolism
3. Thrombosis

Question 16

State the predisposing factors of a stroke caused by cerebral infarction?

Answer 16

1. Heart disease (e.g. infective endocarditis, endocardial thrombus)
2. Hypertension
3. Atheroma
4. Diabetes mellitus

Question 17

Describe the clinical presentation of a stroke caused by intracerebral haemorrhage?

Answer 17

sudden onset of stroke with raised intracranial pressure
> 30 day mortality = 80%

Question 18

Describe the pathogenesis of a stroke caused by intracerebral haemorrhage?

Answer 18

rupture of micro-aneurysm or arteriole

Question 19

What are the predisposing factors for a stroke caused by intracerebral haemorrhage?

Answer 19

1. Hypertension
2. Vascular malformation

Question 20

Describe the clinical presentation of a stroke caused by subarachnoid haemorrhage?

Answer 20

sudden headache with meningism
> 30 day mortality = 45%

Question 21

Describe the pathogenesis of a stroke caused by subarachnoid haemorrhage?

Answer 21

Rupture of saccular aneurysm on circle of Willis

Question 22

Describe the predisposing factors for a stroke cause by a subarachnoid haemorrhage?

Answer 22

1. Hypertension
2. Polycystic renal disease

Question 23

Describe the microscopic changes in infarction?

Answer 23

1. increased eosinophilia of neurons
2. neuronal death and cell infiltrate
3. gliosis

Question 24

State causes of subarachnoid haemorrhage?

Answer 24

1. most often due to cerebral artery berry (saccular) aneurysms
2. intracerebral haemorrhages
3. due to bleeding diseases, trauma, tumour, vasculitis etc

Question 25

Describe berry aneurysms?

Answer 25

thin-walled out-pouching usually < 1 cm diameter wall consists usually only of intima rupture at apex, usually into subarachnoid space, but sometimes into brain or both

Question 26

Where are berry aneurysms found?

Answer 26

occur near major branch points on Circle of Willis or just beyond > more common on anterior part of Circle or its branches Note: incidental finding in ~ 2% of post-mortem examinations, multiple in maybe a third of these

Question 27

Describe the causes of berry aneurysms?

Answer 27

1. genetic factors may be important in some cases 2. cigarette smoking and hypertension also predisposing factors 3. may be precipitated by sudden rise in ICP or BP

Question 28

Describe the clinical presentation of berry aneurysms?

Answer 28

1. typically, sudden severe headache and rapid loss of consciousness 2. may show meningism 3. rebleeding common and makes prognosis worse > 10-15% die but most recover consciousness in minutes

Question 29

Describe the early effects of subarachnoid haemorrhage?

Answer 29

increased risk of vasospasm of other vessels which can lead to additional ischaemic injury, espec. if spasm involves Circle of Willis presumably due to vascular mediators

Question 30

Describe the late sequelae of subarachnoid haemorrhage?

Answer 30

1. meningeal fibrosis and scarring 2. possible obstruction of CSF flow/reabsorption

Question 31

Describe CSF in subarachnoid haemorrhage?

Answer 31

1. initially, bright red blood 2. later, yellow colour (xanthochromia) when red cells degenerate

Question 32

Describe Intraparenchymal (intracerebral or cerebral) haemorrhage? Causes?

Answer 32

- 80 % death rate - sudden onset, causing rapid rise in ICP Causes -1. 50%+ associated with hypertension > microaneurysms (of Charcot-Bouchard) > arteriosclerotic branch points 2. remainder due to vascular malformations, bleeding disease, vasculitis etc

Question 33

Intracerebal haemorrhage usually affects? Consequences?

Answer 33

basal ganglia, brainstem, cerebellum or cerebral cortex 1. major tissue disruption and destruction 2. may extend into ventricles and/or subarachnoid space Note: in survivors, haematoma surrounded (like in infarcts) by zone of reaction, then repair with gliosis

Question 34

Name other causes of haemorrhage?

Answer 34

1. angiomas 2. AV malformations etc

Question 35

Describe the importance of hypertension in CVD? What does it cause? Associated with?

Answer 35

1. common cause of CVD 2. frequently associated with atheroma and diabetes 3. responsible for: a. intracerebral haemorrhage b. rupture of berry aneurysms, so subarachnoid haemorrhage c. lacunar infarcts d. hypertensive encephalopathy (acute or chronic)

Question 36

Describe hypertension and lacunar infarcts?

Answer 36

- arteriosclerosis +/- occlusion of vessels supplying basal ganglia, hemispheres and brainstem - causes single/multiple small cavitated infarcts (“lacunes”) > tissue loss with scattered compound granular corpuscles surrounded by gliosis - clinical effects depend on location : may be “silent”

Question 37

Describe acute hypertensive encephalopathy? Cause? Pathology?

Answer 37

1. Definition - syndrome of diffuse cerebral dysfunction > headaches, confusion, vomiting and convulsions, sometimes leading to coma 2. Cause - usually part of accelerated (malignant) phase hypertension - rapid treatment needed to reduce raised ICP 3. Pathology - oedematous brain +/- tentorial or tonsillar herniation - arteriolar fibrinoid necrosis and petechiae throughout brain

Question 38

Describe chronic hypertensive encephalopathy? Causes? Consequences?

Answer 38

1. Consequences one cause of vascular (multi-infarct) dementia - dementia often with focal neurological defects 2. Causes caused by multifocal vascular disease over long time i. cerebral atheroma ii. thrombosis or embolism from carotids or heart iii. cerebral hypertensive arteriolosclerosis

Question 39

Summarize intracranial vascular pathology?

Answer 39

1. Extradural and subdural haemorrhage - almost always trauma 2. Subarachnoid haemorrhage - most often berry aneurysms 3. Intracerebral haemorrhage - especially in hypertension 4. Cerebral infarction - usually atheroma/thrombosis/embolism