Cerebrovascular Disease

Question 1

rapid necrosis of nerve cells and/or their processes most commonly leads to what clinical picture?

Answer 1

sudden acute functional (stroke)

Question 2

slow atrophy of nerve cells and/or their processes most commonly leads to what clinical picture?

Answer 2

gradually increasing dysfunction (age related cerebral atrophy)

Question 3

how does acute neuronal injury appear microscopically?

Answer 3

shrunken and angulated nuclei
loss of nucleolus
intensely red cytoplasm - “red neurone”

Question 4

at what stage are red neurones normally seen microscopically?

Answer 4

after hypoxia / ischaemia
typically visible 12-24 hrs after irreversible insult (stroke)
shows neuronal cell death

Question 5

if an axon is severed, what occurs in either side of damage?

Answer 5

cell body swelling, enlarged nucleolus

degeneration of axon and myelin sheath distal to injury

Question 6

what are the main functions of astrocytes?

Answer 6

maintain the BBB

involved in repair and scar formation (due to lack of fibroblasts)

Question 7

how do astrocytes usually respond to CNS injury?

Answer 7

gliosis = astrocyte hyperplasia and hypertrophy

this is indicator of CNS injury, regardless of cause

Question 8

how does old gliosis appear histologically?

Answer 8

nuclei become small and dark

they lie in a dense net of processes (glial fibrils)

Question 9

what type of damage are oligodendrocytes particularly susceptible to?

Answer 9

oxidative damage

Question 10

how do ependymal cells (which line ventricles) respond to CNS injury?

Answer 10

limited reaction to injury

disruption causes local proliferation of these cells - small irregularities on the ventricular surfaces “ependymal granulations”

Question 11

how do the microglia (macrophage like cells) respond to CNS injury?

Answer 11

proliferate
recruited through inflammatory mediators
aggregate around necrotic and damaged tissues
M2 more acute, M1 - chronic

Question 12

why does the brain deteriorate so quickly once hypoxia and ischaemia occur?

Answer 12

no O2 to create more ATP

mitochondria inhibit ATP synthesis so reserve is consumed within few mins

Question 13

why can excito-toxicity cause oxidative stress in neurones?

Answer 13

excitatory signal depolarises neurone and releases glutamate

lack of energy means astrocytes don’t reuptake glutamate

loss of glutamate in synapse causes lots Ca2+ entry into post-synaptic terminal = mitochondrial dysfunction and oxidative stress

Question 14

what are the 4 main types of oedema in the brain?

Answer 14

cytotoxic oedema
ionic/osmotic oedema
vasogenic oedema
haemorrhagic conversion

Question 15

what causes cytotoxic oedema?

Answer 15

Na+/K+ channel dysfunction -> cells retain Na+ and water

Question 16

what causes ionic/osmotic oedema?

Answer 16

water and Na+ from capillaries move into brain parenchymal extracellular space

Question 17

what causes vasogenic oedema?

Answer 17

BBB disrupted -> leaking fluid from capillaries affect white matter

Question 18

what causes haemorrhagic conversion?

Answer 18

when RBCs cross BBB

Question 19

what is meant by cerebrovascular disease?

Answer 19

an abnormality of brain caused by pathological process in blood vessels

Question 20

what are the 4 main components of cerebrovascular disease?

Answer 20

brain ischaemia and infarction
haemorrhages
vascular malformations
aneurysms

Question 21

what would cause a global hypoxia and ischaemic damage to the brain as opposed to focal area of ischaemia?

Answer 21

cardiac arrest and severe hypotension (trauma with hypovolaemic shock)

focal = vascular obstruction

Question 22

what is the definition of a stroke?

Answer 22

sudden disturbance of cerebral function of vascular origin that causes death or lasts over 24 hours

Question 23

what gender and age are most common for stroke to occur?

Answer 23

peak incidence is >70yrs

men > women

Question 24

strokes caused by atherosclerotic thrombus are most common in which artery of cerebrum?

Answer 24

middle cerebral artery or its branches

Question 25

where do embolic strokes usually originate from?

Answer 25

atheroma in internal carotid or aortic arch | emboli from heart due to AF

Question 26

what are risk factors for cerebral infarction?

Answer 26

``` hypertension serum lipids, obesity, diet diabetes mellitus heart disease drugs smoking ```

Question 27

what symptoms do patients often experience if they have a stroke due to carotid artery disease?

Answer 27

contra-lateral weakness / sensory loss if dominant hemisphere, may be aphasia or apraxia

Question 28

what symptoms would usually indicate a middle cerebral artery stroke?

Answer 28

weakness in contralateral face and arm

Question 29

what symptoms would usually indicate an anterior cerebral artery stroke?

Answer 29

weakness and sensory loss in contralateral leg

Question 30

strokes in vertebro-basilar arteries can cause what symptoms?

Answer 30

vertigo ataxia dysarthria dysphasia

Question 31

what is meant by vascular remodelling and how can this perpetuate a stroke?

Answer 31

accelerated atherosclerosis arteriolosclerosis (thick, stiff vessel walls prone to rupture) eventual fibrinoid necrosis of vessel walls

Question 32

where do micro aneurysms most commonly occur in the brain circulation?

Answer 32

branches of middle cerebral artery near the basal ganglia

Question 33

what is a lacunar infarct?

Answer 33

small "lake" like infarcts up to 15mm diameter | due to damage of lenticulostriate arteries in basal ganglia

Question 34

when can lacunar infarcts cause most damage?

Answer 34

if extends into internal capsule - can cause extensive motor weakness in face and limbs

Question 35

what are the hallmarks of hypertensive encephalopathy?

Answer 35

global cerebral oedema tentorial and tonsillar herniation (due to raised ICP) petechiae anteriolar fibrinoid necrosis - high BP

Question 36

what are the clinical findings of hypertensive encephalopathy?

Answer 36

severe hypertension and symptoms of raised ICP

Question 37

where do most intracerebral haemorrhages occur?

Answer 37

most common - basal ganglia thalamus, cerebral white matter and cerebellum

Question 38

how do intracerebral haemorrhages appear macroscopically?

Answer 38

``` asymmetrical shifts and herniations of brain well demarcated softening of adjacent tissue surrounding oedema ```

Question 39

what vascular malformations can predispose to cerebrovascular disease?

Answer 39

arteriovenous malformations | cavernous / venous angiomas

Question 40

why do vascular malformations predispose to haemorrhage?

Answer 40

shunting from artery to vein = vein undergoes smooth muscle hypertrophy, vein is not compliant and ruptures easily can also form aneurysms which rupture

Question 41

what normally causes a subarachnoid haemorrhage?

Answer 41

rupture of a saccular aneurysm (berry aneurysms)

Question 42

where do berry aneurysms normally occur?

Answer 42

internal carotid artery vertebro-basilar circulation *usually at arterial bifurcations

Question 43

what can be seen macroscopically around a berry aneurysm?

Answer 43

intracerebral haematomas next to aneurysms infarcts of brain parenchyma - due to arterial spasm haematoma may compress structures and cause features of raised ICP

Question 44

what are the risk factors for berry aneurysms?

Answer 44

smoking hypertension kidney disease

Question 45

what symptoms are usually experiences upon rupture of berry aneurysm?

Answer 45

severe headache vomiting LOC