stroke 2

Question 1

Define stroke

Answer 1

Stroke, AKA a ‘cerebrovascular accident’, is a ‘serious life threatening condition that occurs when the blood supply to part of the brain is cut off’. The symptoms and signs persist for more than 24 hours

Question 2

Define TIA

Answer 2

Transient ischaemic attacks (TIAs), sometimes colloquially called ‘mini strokes’, have similar clinical features of a stroke but completely resolve within 24 hours

Question 3

What are types of stroke

Answer 3

Types of strokeoIschaemic (85%)
-Thromboembolico

Haemorrhagic (10%)

• Intracerebral (rupture of a vessel in brain parenchyma)
• Subarachnoid

Other (15%)

• Dissection (separation of walls of artery, can occlude branches)
• Venous sinus thrombosis (occlusion of veins causes backpressure and ischaemia due to reduced blood flow)
• Hypoxic brain injury (e.g. post cardiac arrest

Question 4

What are the 2 main principles of emergency management of stroke

Answer 4

Two main principle
s Are they within the window for thrombolysis (<4 hours)?
 Do a CT head to determine if it is a bleed (if bleed cannot proceed with thrombolysis)

Question 5

How would CT/MRI appear in ischaemia and haemorrhage

Answer 5

 CT
•Ischaemic area of brain not visible early on (as infarct becomes more established the ischaemic area will become hypodense)
•A bleed will show up as a bright white area, maybe with mass effect
 MRI
•Sometimes performed
•Ischaemia shows up as a high signal area

Question 6

What are the symptoms of ACE infarct

Answer 6

Contralateral lower limb weakness and sensory changes
Urinary incontnence
Apraxia
Dysartrhria/Aphasia
Split brain syndrome

Question 7

What are the sensory changes in ACA

Answer 7

oAnterior cerebral artery (ACA) infarct
 Contralateral weakness in lower limb
 Lower limb affected much worse than upper limb and face
 Contralateral sensory changes in same pattern as motor deficits (sensory homunculus in similar arrangement as motor homunculus)

Question 8

Why do you get urinary incontinence in ACE infarct

Answer 8

 Urinary incontinence due to paracentral lobules being affected•Paracentral lobules are essentially the most medial part of the motor/sensory cortices and supply the perineal area

Question 9

What is apraxia and why does it occur in ace infarct

Answer 9

Inability to complete motor planning (e.g. difficulty dressing oneself even when power is normal)•Often caused by damage to left frontal lobe

Question 10

What is dysarthria/aphasia and why doe it occur in aca infarct

Answer 10

A very unusual sign in ACA infarcts compared with MCA infarcts•May be related to frontal lobe damage

Question 11

Why does split brain/alien hand syndrom occur

Answer 11

Split brain syndrome / alien hand syndrome (both rare)•Caused by involvement of corpus callosum which is normally supplied by the ACA

Question 12

Give an overview of MCA infarct

Answer 12

oMiddle cerebral artery (MCA) infarct
 As MCA supplies a large area of brain these stroke can have very widespread effects and are associated with an 80% mortality if the main trunk of the MCA is affected due to resulting cerebral oedema
 Haemorrhagic transformation can occur if the vessels in the infarcted area break down
 MCA can be occluded at three main points

Question 13

What are 3 points at which the mca can become occluded

Answer 13

Proximan main stem before lenticulostriate arteries come off

Lenticulostriate

More Distal branches

Question 14

What are teh effects seen in a proximal MCA infarct

Answer 14

oIn this case, all branches of MCA will be affected including lenticulostriates and distal branches to cortical areas

• Contralateral full hemiparesis (face, arm and leg affected)
• Contralateral sensory loss
• Visual field degefects
• Aphasia
• Contralateral neglect

Question 15

Why do you get contralateral full hemiparesis in MCA infarct (ie why is leg not spared)

Answer 15

Contralateral full hemiparesis (face, arm and leg affected)
- Because the internal capsule has been affected which carries fibres to face, arm and leg so even though the MCA supplies the face and arm area of the motor homunculus, this is irrelevant

Question 16

Why do you get contralateral sensory loss in MCA infarct

Answer 16

Contralateral sensory loss Probably in the distribution of primary sensory cortex supplied by MCA (i.e. face and arm), but could involve larger areas if sensory fibres in internal capsule affected

Question 17

What are the visual field defects seen in MCA infarct and why

Answer 17

Visual field defects Usually contralateral homonymous hemianopia without macular sparing
•Due to destruction of both superior and inferior optic radiations as they run through (superior) temporal and parietal lobes
•More distal occlusions may affect one radiation alone causing quadrantanopias

Question 18

Decribe aphasia in MCA infarct

Answer 18

oAphasia
 Global if dominant (usually left) hemisphere affected)
•Therefore, cannot understand or articulate words

Question 19

Why can neglect occur in MCA infarct and what are the typical features

Answer 19

oContralateral neglect
 Usually in lesions of right parietal lobe (can be caused by occlusions of more distalbranches as well)
 Essentially an issue with not ‘acknowledging’ that the usually left side of space or even your own body exists. Visual fields normal
 Other features
• Tactile extinction (if touch each side simultaneously doesn’t feel the affected side)
•Visual extinction (as with half clock face etc.)
•Anosognosia (literally does not acknowledge that they have had a stroke, so will confabulate to explain disability)

Question 20

What are lacunar strokes?

Answer 20

•Lenticulostriate artery(ies) occluded
oAKA lacunar strokes
oCause destruction of small areas of internal capsule and basal ganglia
oEssential distinguishing feature from, say, a proximal MCA infarct is that they do not cause cortical features (e.g. neglect or aphasia

Question 21

What are the types of lacunar stroke

Answer 21

oTypes
 Pure motor (face, arm and leg affected equally, caused by damage to motor fibres travelling through internal capsule due to occlusion of lenticulostriate arteries)
 Pure sensory (face, arm and leg affected equally, caused by damage to sensory fibres travelling through internal capsule probably due to occlusion of thalamoperforator arteries and maybe also lenticulostriate)
 Sensorimotor (mixed, caused by infarct occurring somewhere at boundary between motor and sensory fibres)
 Many other syndromes have been recognised which you need to know less abou

Question 22

What ahppenes if the superior branch of MCA is occluded

Answer 22

oMCA splits into a superior and inferior division
 Superior division essentially supplies lateralfrontal lobe
•Including primary motor cortex and Broca’s area
•Occlusion will cause contralateralface and arm weakness and expressive aphasia if left hemisphere affected

Question 23

What happenes if the inferior division of MAC is occluded

Answer 23

Inferior division essentially supplies lateral parietal lobe and superior temporal lobe
•Including primary sensory cortex, Wernicke’s area and both optic radiations
•Occlusion will cause contralateralsensory change in face and arm, receptive aphasia if left hemisphere and contralateral visual field defectwithout macular sparing (often homonymous hemianopia as both radiations damaged)

Question 24

What happens in coclusion even more distal to sup/inf brances of MCA

Answer 24

oOcclusion of branches distal to superior/inferior division may produce even more specific effects,
e.g. taking out Broca’s areas specifically with no motor defici

Question 25

Describe PCA infacrt

Answer 25

Posterior cerebral artery (PCA) Somatosensory and visual dysfunction typical
•Contralateral homonymous hemianopia (with macular sparing due to collateral supply from MCA)
•Contralateral sensory loss due to damage to thalamus

Question 26

Describe cerebellar infarcts

Answer 26

oCerebellar infarcts
 Symptoms
•Nausea
•Vomiting
•Headache
•Vertigo / dizziness
 Ipsilateral cerebellar signs (remember DANISH)
 Possible ipsilateral brainstem signs since cerebellar arteries supply brainstem as they loop round to the cerebellum
 Possible contralateral sensory deficit / ipsilateral Horner’s (once again due to brainstem involvement

Question 27

What are the cerebellar signs

Answer 27

Dysdiadochokinesia
Ataxia
Nystagmus
Intention tremor
Slurred speech
Hypotonia

Question 28

Desribe brain stem strokes

Answer 28

Brainstem strokes
 A huge number of named syndromes (not important to know specifics)
 A typical feature is that contralateral limb weakness is seen with ipsilateral cranial nerve signs
•This can be explained by damage to corticospinal tracts (above decussation of pyramids) and damage to cranial nerve nuclei on same side

Question 29

Gibve an overview of basilar artery occlusion

Answer 29

oBasilar artery occlusion
 As this vessel supplies the brainstem (which contains many vital centres), occlusion can sometimes cause sudden death

Question 30

What happens in distal basilar occlusion

Answer 30

Occlusion of distal (superior) basilar artery
•Visual and oculomotor deficits (as basilar sends some branches to midbrain which contains oculomotor nuclei. Also, occlusion at this site can prevent blood flowing into PCAs affecting occipital lobes)
•Behavioural abnormalities
•Somnolence, hallucinations and dreamlike behaviour (as brainstem contains important centres for sleep regulation – reticular activating system etc.)
•Motor dysfunction often absent (if the cerebral peduncles can get blood from the PCAs which in turn are being filled by the posterior communicating arteries)

Question 31

Describ eproximal basilar occlusion

Answer 31

Proximal basilar occlusion (at level of pontine branches. Embolus in basilar artery can occlude pontine branches on each side)
•Can cause locked in syndrome
•Complete loss of movement of limbs however preserved ocular movement. Eyes still move because midbrain is getting supply from PCAs via posterior communicating arteries
•Preserved consciousness (maybe because midbrain reticular formation is still intact)

Question 32

What is the bramford/Oxford stroke classification

Answer 32

•Bamford (Oxford) stroke classification
oThis is a clinical tool to quickly diagnose strokes
oIt is based upon all the neuroanatomy you have learnt so far
oIt will be an informative exercise for you to go through the classificationand try to unpick the rationale for the different types