Strokes Flashcards
Define the term “stroke”
The damaging or killing of brain cells starved of oxygen as a result of the bloody supply to part of the brain being cut off
Define the term “Transient Ischaemic Attack (TIA)”
A stroke that recovers in 24 hours from the onset of symptoms
What is a stroke syndrome?
A group of signs and symptoms that are produced due to the occlusion or damage of an artery supplying part of the brain
What are the main types of stoke and the % of each that make up all strokes?
Ischaemic 85%
Haemorrhagic 10%
Other 5%
Which are the most common two sites for the clot to travel from to the brain to cause an ischaemic stroke?
The carotid arteries
The heart
Which conditions can increase the risk of thrombus and therefore of stroke?
Atrial fibrillation
Valvular disease
Endocarditis
Atherosclerosis
Anterior circulation to the brain comes from which arteries?
Internal carotids
Posterior circulation of the brain is supplied by which arteries?
Vertebral arteries
What are the 4 key questions when investigating stroke syndromes?
- What artery has been affected?
- What area of the brain does it supply?
- What does this part of the brain do?
- How will the patient present if these areas are damaged?
Talk through (using the 4 questions) how a stroke syndrome involving occlusion/blockage of their LEFT anterior cerebral artery may present?
- Lt Anterior Cerebral Artery
- Lt anterior cerebral artery supplies the medial aspects of the frontal and parietal lobes and the anterior part of the corpus callosum
- This part of the brain is responsible for CONTRALATERAL motor and sensory supply to the LOWER limb and genitals.
Motor- flaccid paralysis followed by UMN signs
Sensory- loss of all sensory modalities of lower limb
- Presentation: Loss of voluntary control of micturition i.e. urinary incontinence, split brain syndrome/ alien hand syndrome due to loss of supply to corpus callosum
Talk through (using the 4 questions) how a stroke syndrome involving occlusion/blockage of their LEFT middle cerebral artery may present?
- Lt MIDDLE cerebral artery
- Supplies: majority of the hemisphere, basal ganglia, internal capsule, macular cortex
- What does this part of the brain do? DEPENDS on how proximal/distal the blockage is…
Main trunk occlusions causes considerable oedema —-> coma, death
- Presentation: CONTRALATERAL loss of all sensory modalities in the UPPER limb and face
CONTRALATERAL initial flaccid paralysis followed by UMN signs
Why might a patient still get leg symptoms with occlusion/damage to the left MIDDLE cerebral artery?
If the blockage is proximal
The blood supply to lenticulostriate arteries is compromised
The lenticulostriate arteries supply the internal capsule which carries descending motor fibres from the entire motor cortex
Note: distal blockage will spare the internal capsule supply
Describe the difference in symptom presentation between proximal and distal occlusion/damage to the middle cerebral artery for both speech and vision.
Proximal:
Vision: Contralateral homonymous hemianopia
Speech: Broca’s aphasia
Distal:
Vision: Contralateral homonymous superior quadrantanopia (or inferior-rare)
Speech: Wernicke’s aphasia
Main trunk:
Global aphasia
Talk through (using the 4 questions) how a stroke syndrome involving occlusion/blockage of their LEFT posterior cerebral artery may present?
- Left posterior cerebral artery
- Occipital lobe, inferior temporal lobe, thalamus, posterior limb of the internal capsule
- Visual cortex is located here
- Visual effects: contralateral homonymous hemianopia with macula sparing
Talk through (using the 4 questions) how a stroke syndrome involving occlusion/blockage of their cerebellar artery may present?
- Cerebellar artery
- Supplies the cerebellum
- Co-ordiates all movement
- Cerebellar signs (DANISH)
Dysdiadochokinesia
Ataxia
Nystagmus
Intention tremor
Slurred
Talk through (using the 4 questions) how a stroke syndrome involving occlusion/blockage of their cerebellar artery may present?
- Cerebellar artery
- Cerebellum
- Co-ordination of movement
- Cerebellar signs (DANISH)
Dysdiadokinesia
Ataxia
Nystagmus
Intention tremor
Slurred speech
Hypotonia
Apart from the cerebellum, the cerebellar arteries also supply what?
The brainstem
What are the differences in the presentation between proximal and distal cerebellar artery occlusion?
Proximal: Brainstem and cerebellar signs
Distal: Cerebellar signs alone
What are brainstem signs?
“Crossed signs”
i.e. damage to the ascending/descending tracts affects contralateral side
damage to crainial nerves or their nuclei gives ipsilateral signs
Talk through (using the 4 questions) how a stroke syndrome involving occlusion/blockage of their basilar artery may present?
- Basilar artery
- Supplies the medulla, cerebellum, pons, midbrain, thalamus, and occipital cortex
- Depends on where the occlusion is.
Distal- loss of both posterior cerebral arteries, bilateral lobe, thalamic (all sensory information), midbrain infarction
Proximal- “locked-in” syndrome
- Complete anaesthesia, locked in syndrome
What is a lacunar stroke?
A stroke arising from the small penetrating arteries that supply deep subcortical structures.
Talk through (using the 4 questions) how a stroke syndrome involving occlusion/blockage of their left lenticulotriate artery may present?
- Left lenticulostriate artery (small branch of the MCA)
- Supplies: The internal capsule
- What does that part do: Carries motor fibres to the leg, trunk and arm as well as the face
- Presentation: Isolated, contralateral (right-sided) paralysis involving face, trunk, upper and lower limb.
=PURE MOTOR hemiparesis
Talk through (using the 4 questions) how a stroke syndrome involving occlusion/blockage of their LEFT thalamoperforator artery may present?
- Artery: Left thalamoperforator artery (small branch of PCA)
- Supplies: Part of the thalamus
- What does this part do;: Relays sensory information to the left post-central gyrus (somatosensory cortex)
- Presentation: Isolated, contralateral (right-sided) loss of all sensory modalities of the face, trunk and upper & lower limb.
= PURE SENSORY STROKE
How are strokes classified according to the Oxfordshire Community Stroke Project (OCSP)?
How does stroke visualisation on CT imaging differ between acute and a stroke that has happened in the past or >1 hour previous to the scan?
Acute: may not be visible in the parenchyma, HYPERdense artery may be seen
Longer: parenchymal changes, grey matter becomes HYPOdense
Not every case of weakness or dysphasia is stroke, give some differentials using the accronym “HEMI”.
Hypoglycaemia
Epilespy
Migrane (hemipalegic)
Intracranial tumours/infections
