Strokes occur when blood supply to part of the brain is cut off.
Compare Stroke and TIA
Stroke- Symptoms and signs persist for >24h
TIA- Completely resolve within 24h
What are the 3 types of Stroke
What percentage of all strokes do these make up?
- Ischaemic, 85% (Thromboembolic)
- Haemorrhagic 10% (Intracerebral, Subarachnoid)
- Other (5%)
What are 3 causes of non-ischaemic, non-haemorrhagic stroke
- Dissection (separation of walls of artery, can occlude branches)
- Venous Sinus Thrombosis (Vein occlusion-> Backpressure + Ischaemia)
- Hypoxic brain injury (after cardiac arrest)
What are the 2 main principles of emergency stroke treatment?
- Are they within the window for thrombolysis (<4 hrs)
- Head CT to determine if it is a bleed (Cannot do thrombolysis if there is a bleed)
How does an acute stroke look on a head CT?
- Ischaemic area not visible early on
- Bleed shows up as bright white area (maybe with mass effect)
An MRI is sometimes performed to diagnose acute stroke.
How does it look?
Ischaemia shows up as a high signal area
What do the clinical features of a stroke depend on?
Whether Anterior or Posterior circulation is affected, AND whether pathology is in Proximal or Distal territory
List 6 signs of ACA infarct
- Contralateral lower limb weakness (Worse than upper limb + face as ACA supplies medial cortex)
- Contralateral sensory changes (same pattern as motor deficit)
- Urinary Incontinence
- Apraxia (Inability to complete motor planning, often caused by left frontal lobe damage)
- Dysarthria/ Aphasia (Unusual in ACA infarct)
- Split brain/ Alien hand syndrome (Involvement of Corpus Callosum)
In ACA infarct, why do you get Urinary incontinence?
As paracentral lobules are affected
most medial part of sensory/ motor cortices and supply perineal area
Describe briefly the range of effects and mortality of a MCA infarct
- Very widespread effects (as MCA supplies large area of brain)
- 80% mortality if main MCA trunk affected, due to Cerebral Oedema
What can occur in an MCA infarct if the vessels in the infarcted area break down?
Haemorrhagic transformation
What are the 3 points of the MCA where an occlusion can occur
- Proximal (before deep branches come off)
- Leneticulostriate arteries (Lacunar strokes)
- Distal branches (Superior or inferior divisions)
If the Proximal MCA is occluded, all the the branches will be affected
List 5 main signs of a Proximal MCA occlusion
- Contralateral full hemiparesis (Internal Capsule affected so Face, Arm, Leg fibres all affected)
- Contralateral sensory loss (Face, Arm usually, but legs too if IC affected)
- Contralateral Homonymous Hemianopia WITHOUT macular sparing, as both S+I Optic Radiations affected.
- Aphasia (Global, if left hemisphere affected)
- Contralateral neglect (Usually if right parietal lobe affected, normal visual fields)
List 3 additional/ possible signs of a Proximal MCA infarct
- Tactile extinction (if you touch each side at the same time, doesn’t feel the affected side)
- Visual extinction (doesn’t see half of frontal view)
- Anosognosia (doesn’t acknowledge that they had a stroke)
Leneticulostriate artery occlusions/ Lacunar strokes cause destruction of small areas of Internal Capsule and Basal ganglia
What’s their defining feature in comparison to a Proximal MCA infarct
Lacunar strokes do not cause cortical features (neglect or aphasia)
What are 3 types of signs causes by Lacunar strokes?
- Pure motor (damage to motor fibres through IC)
- Pure sensory (damage to sensory fibres through IC)
- Sensorimotor (Infarct at boundary between M and S fibres)
What are the 2 branches of the distal MCA?
What regions do they supply?
Superior division ;
- Supplies lateral Frontal lobe
- Including Motor Cortex and Broca’s Area
Inferior division;
- Supplies Lateral Parietal and Superior Temporal lobes
- Including Sensory Cortex, Wernicke’s Area and both Optic Radiations
Compare the signs of an occlusion of the Superior and Inferior divisions of the distal MCA
Superior;
- Contralateral Face + Arm weakness
- Expressive Aphasia if left hemisphere affected
Inferior;
- Contralateral sensory change in Face + Arm
- Receptive aphasia if left hemisphere affected
- Contralateral Homonymous Hemianopia
(More distal occlusions can have more specific effects e.g Broca’s area affected but not Motor cortex)
List 2 signs of a PCA infarct
- Contralateral sensory loss (thalamus damage)
- Contralateral Homonymous Hemianopia WITH macular sparing (collateral MCA supply)
List 4 SYMPTOMS of Cerebellar Infarcts
Not the Ipsilateral signs- DANISH
- Nausea
- Vertigo/ Dizziness
- Vomiting
- Headache
List 3 types of signs of Cerebellar infarcts
- DANISH
- Ipsilateral Brainstem signs (Cerebellar arteries supply brainstem)
- Contralateral Sensory deficit/ Ipsilateral Horner’s
What are 2 typical features of Brainstem strokes?
- Contralateral limb weakness
- Ipsilateral cranial nerve signs
The Basilar artery can be occluded Proximally or Distally.
Explain a major consequence of a BA occlusion.
Can cause sudden death as the BA supplies the brainstem
List 3 signs of a Distal/ Superior Basilar Artery Occlusion
- Visual and Oculomotor defects (BA sends branches to Midbrain, where CNIII nucleus is)
- Behavioural abnormalities
- Somnolence, Hallucinations, Dream like behaviour
(Motor dysfunction often absent if cerebral peduncles can get blood from PCAs which are filled via Post. Communicating Arteries)
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Nervous System Topography45
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Psychotic Disorders27
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Mood Disorders24
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Anxiety Disorders30
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Subarachnoid Haemorrhage & Meningitis31
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Raised Intracranial Pressure33
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Stroke32
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Headache28
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Dementia and Delirium34
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Neuropathology36
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Consciousness30
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Higher Cortical Funtion37
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Motor Disorders32
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Motor System35
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Visual System36
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Blood Supply to The Brain20
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The Somatosensory System43
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Cellular Physiology Of The Brain45
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Nervous System Development36
