Stroke Flashcards
1
Q
What is a stroke?
A
- A serious, life-threatening condition that occurs when the blood supply to part of the brain is cut off
- Symptoms and signs persist for more than 24 hours
2
Q
What are transient ischaemic attacks?
A
- Have similar clinical features of a stroke but completely resolve within 24 hours
3
Q
What are the different types of stroke?
A
- Ischaemic (85%) - thromboembolic
- Haemorrhagic (10%) - intracerebral and subarachnoid
- Other (15%) - dissection, venous sinus thrombosis, hypoxic brain injury
4
Q
What is a dissection that causes stroke?
A
- Separation of walls of artery, can occlude branches
5
Q
What is a venous sinus thrombosis?
A
- Occlusion of veins causes backpressure and ischaemia due to reduced blood flow
6
Q
What are the two main principles of stroke management?
A
- Is the patient within the window for thrombolysis (<4 hours)
- Do a CT head to determine if it is a bleed (if there’s a bleed, cannot proceed with thrombolysis)
7
Q
What are the different mechanisms of acute imaging of a stroke?
A
- CT
- MRI
8
Q
How does stroke appear in a CT head?
A
- Ischaemic area of brain not visible early on (as infarct becomes more established the ischaemic area will become hypodense)
- A bled will show up as a bright white area, maybe with mass effect
9
Q
How does stroke appear in an MRI?
A
- Shows up as a high signal area
10
Q
What are the classic stroke syndromes?
A
- Anterior cerebral artery infarct
- Middle cerebral artery infarct
- Posterior cerebral artery infarct
- Cerebellar infarct
- Brainstem strokes
- Basilar artery occlusion
11
Q
What are the motor symptoms of an anterior cerebral artery infarct?
A
- Contralateral weakness in lower limb (affected worse than upper limb and face)
12
Q
What are the sensory symptoms of an anterior cerebral artery infarct?
A
- Contralateral sensory changes in same pattern as motor deficits
- Lower limb is affected worse than upper limb and face
13
Q
What are the other symptoms of an anterior cerebral artery infarct?
A
- Urinary incontinence due to paracentral lobules being affected
- Apraxia
- Dysarthria/aphasia
- Split brain syndrome/alien hand syndrome
14
Q
What are the paracentral lobules?
A
- Essentially the most medial part of the motor/sensory cortices
- Supplies perineal area
15
Q
What is apraxia?
A
- Inability to complete motor planning e.g. difficulty dressing oneself even when power is normal
- Often caused by damage to left frontal lobe
16
Q
Is it common to see dysarthria/aphasia in an ACA infarct?
A
- Very unusual
- Much more common in MCA infarcts
17
Q
What causes split brain syndrome/alien hand syndrome?
A
- ## Caused by involvement of corpus callosum which is normally supplied by the ACA
18
Q
Give an overview of occlusion of the MCA?
A
- MCA supplies a large area of brain
- Effects are widespread
- 80% mortality if main trunk of MCA is affected due to resulting cerebral oedema
- Haemorrhagic transformation can occur if the vessels in the infarcted area break down
19
Q
Where can the MCA be occluded?
A
- Proximal
- Lenticulostriate arteries
- More distal branches
20
Q
How much of the MCA is affected if the proximal part gets occluded?
A
- All branches of MCA are affected, including lenticulostriates and distal branches to cortical areas
21
Q
What are the motor effects of a proximal MCA stroke?
A
- Contralateral hemiparesis (face, arm and leg affected)
22
Q
Why does a proximal MCA stroke cause contralateral hemiparesis?
A
- Internal capsule has been affected, which carries fibres to face, arm and leg
23
Q
What are the sensory effects of a proximal MCA stroke?
A
- Contralateral sensory loss in the distribution of the primary sensory cortex supplied by the MCA (face and arm)
- Could involve larger areas if sensory fibres in the internal capsule are affected
24
Q
What visual field defects are caused by a proximal MCA stroke?
A
- Contralateral homonymous hemianopia without macula sparing
25
Why does a proximal MCA stroke cause a contralateral homonymous hemianopia without macula sparing?
- Due to destruction of both superior and inferior optic radiations as they run through the temporal and parietal lobes
- More distal occlusions may affect one radiation alone, causing a quadrantanopia
26
What are some other features of a proximal MCA stroke?
- Aphasia
- Contralateral neglect
27
Why does a proximal MCA stroke cause aphasia?
- Global if dominant (usually left) hemisphere is affected
- Cannot understand or articulate words
28
Why does a proximal MCA stroke cause contralateral neglect?
- Usually due to lesions of right parietal lobe
- Is essentially an issue with not acknowledging that one half of the body and space does not exist
- Visual fields normal
- Can result in tactile extinction, visual extinction and anosognosia on affected side
29
What is the name given to a stroke caused by occlusion of the lenticulostriate arteries?
- Lacunar stroke
30
What does lacunar infarct do to the brain?
- Destruction of small areas of internal capsule and basal ganglia
31
What distinguishes a lacunar infarct from other kinds of stroke?
- These do not cause cortical features e.g. neglect or aphasia
32
What are the types of lacunar infarct?
- Pure motor
- Pure sensory
- Sensorimotor
33
What are the features of a pure motor lacunar infarct?
- Face, arm and leg are affected equally
- Caused by damage to motor fibres travelling through the internal capsule
- Due to occlusion of lenticulostriate vessels
34
What are the features of a pure sensory lacunar infarct?
- Face, arm and leg affected equally, caused by damage to sensory fibres travelling through internal capsule
- Most likely due to occlusion of thalamoperforator arteries
35
What causes a sensorimotor lacunar infarct?
- Caused by infarct occurring somewhere at boundary between motor and sensory fibres
36
What are the divisions of the MCA?
- Superior and inferior
37
What does the superior division of the MCA supply?
- Essentially supplies lateral front lobe
- Including primary motor cortex and Broca's area
38
What will occlusion of the superior division of the MCA result in?
- Contralateral face and arm weakness
- Expressive aphasia if left hemisphere is affected
39
What does the inferior division of the MCA supply?
- Lateral parietal lobe and superior temporal lobe
- Includes primary sensory cortex, Wernicke's area and both optic radiations
40
What will occlusion of the inferior division of the MCA result in?
- Contralateral sensory change in face and arm
- Receptive aphasia if left hemisphere
- Contralateral visual field defect without macula sparing (often homonymous hemianopia as both radiations are damaged)
41
What can occlusion of branches distal to the superior/inferior division of the MCA cause?
- Very specific effects
- E.g. taking out Broca's areas specifically with no motor deficit
42
What are the symptoms of PCA occlusion?
- 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
43
What does Danish stand for in terms of cerebellar signs?
Dysdiadochokinesia
Ataxia (gait and posture)
Nystagmus
Intention tremor
Slurred, staccato speech
Hypotonia/heel-shin test
44
What are the symptoms of a cerebellar stroke?
- Nausea
- Vomiting
- Headache
- Vertigo/dizziness
- Ipsilateral cerebellar signs
- Possible ipsilateral brainstem signs
- Possible contralateral sensory deficit
- Ipsilateral Horner's
45
Why do we get ipsilateral brainstem signs during a cerebellar stroke?
- Cerebellar arteries supply the brainstem as they loop around the cerebellum
46
What are the symptoms of brainstem strokes?
- A huge number of named syndromes
- Typical feature is contralateral limb weakness seen with ipsilateral cranial nerve signs
47
Why do brainstem strokes cause contralateral limb weakness and ipsilateral cranial nerve signs?
- This can be explained by damage to corticospinal tracts (above the decussation of the pyramids) and damage to cranial nerve nuclei on same side
48
What can basilar artery occlusion cause?
- Sudden death because this vessel supplies the brainstem
49
What does occlusion of the superior basilar artery cause?
- Visual and oculomotor deficits
- Behavioural abnormalities
- Somnolence, hallucinations, and dreamlike behaviour
- Motor dysfunction often absent
50
Why do superior basilar artery occlusions cause visual and oculomotor deficits?
- Basilar artery sends some branches to the midbrain which contains oculomotor nuclei
- Also, occlusion at this site can prevent blood flowing into the PCAs, affect the occipital lobes
51
What are the symptoms of proximal basilar artery occlusion?
- Can cause locked in syndrome
- Complete loss of movement of limbs
- Preserved ocular movement
- Preserved consciousness
52
Why does proximal basilar artery occlusion preserve ocular movement?
- Midbrain is getting supply from PCAs via posterior communicating arteries
53
What is the Bamford (Oxford) stroke classification?
- Clinical tool used to quickly diagnose strokes
