S10) Anatomy and Physiology of Stroke Flashcards
What is a stroke?
A stroke is the damaging/killing of brain cells starved of O2 as a result of blood supply to part of the brain being cut off
What is a TIA?
A transient ischaemic attack is a stroke that recovers within 24 hours from the onset of symptoms
What is stroke syndrome?
Stroke syndrome is the constellation of signs and symptoms produced due to occlusion or damage of an artery supplying part of the brain
What are the two main types of stroke?
- Ischaemic (85%)
- Haemmorhagic (10%)
- Other – sissection, venous sinus thrombosis (5%)
In a stroke, what are the possible locations where the clot could have come from?
- Brain
- Carotid arteries
- The vertebral / basilar arteries
- Aorta
- Heart
Provide four possible conditions which could lead to blood clots arising from the heart and causing a stroke
- Atrial Fibrillation
- Valvular disease / prosthetic valves
- Septic emboli (endocarditis)
- Intra-cardiac thrombus
Identify three unusual conditions which could lead to a stroke
- Vasculitis
- Sickle cell anaemia
- Cocaine (coke stroke)
Which part of the brain does the anterior cerebral artery supply?
The anterior cerebral artery supplies the medial aspects of the frontal and parietal lobe and the anterior part of corpus callosum
What does the part of the brain supplied by the ACA do?
How could an anterior cerebral artery stroke affect the parietal lobe and corpus callosum?
- Corpus callosum – split brain syndrome, alien hand syndrome
- Parietal lobes – loss of voluntary control of micturition
How would a patient present with a left ACA stroke?
- Sensory – contralateral loss of all sensory modalities in the lower limb
- Motor –contralateral paralysis in lower limb more so than upper limb (initially flaccid paralysis then spasticity, UMN signs)
Which part of the brain does the middle cerebral artery supply?
Majority of the hemisphere:
- Basal ganglia
- Internal capsule
- Macular cortex
What would be the result of a main trunk occlusion in the middle cerebral artery?
Considerable cerebral oedema:
- May lead to coma/death
- Malignant MCA
What does the part of the brain supplied by the middle cerebral artery do?
How does a patient present with a left MCA stroke?
- Sensory – contralateral loss of all sensory modalities in the upper limb and face
- Motor – contralateral upper limb and face affected more than lower limb (initially flaccid paralysis then spasticity UMN signs)
What will be affected by an occlusion at arrow 1?
Occlusion at this point will affect:
- Lateral motor cortex – responsible for the face and arm
- Internal capsule – carries descending motor fibres from the entirety of the motor cortex (face, arm and leg may be affected)
What will be affected by an occlusion at arrow 2?
Occlusion at this point spares the internal capsule but still damages the lateral motor cortex, thus only the face and arm are affected
What are the visual effects of proximal and distal occlusions of the middle cerebral artery respectively?
- Proximal occlusion of MCA leads to contralateral homonymous hemianopia
- Distal occlusion of the MCA may lead to contralateral homonymous superior or inferior quadrantanopia (rare)
How does a middle cerebral artery occlusion affect speech?
Symptoms depend on:
- Dominant hemisphere
- Which branch of MCA is occluded
What happens if the dominant hemisphere (most likely left) is affected by a middle cerebral artery occlusion?
- Global aphasia caused by main trunk occlusion
- Broca’s (expressive) aphasia
- Wernicke’s (receptive) aphasia
What happens if the non-dominant hemisphere (most likely right) is affected by a middle cerebral artery occlusion?
- Hemispatial neglect
- Tactile extinction
- Visual extinction
- Anosognosia
Which part of the brain is supplied by the posterior cerebral artery?
- Occipital lobe
- Inferior temporal lobe
How does a patient present with a PCA stroke?
Contralateral homonymous hemianopia with macular sparing
Which part of the brain do the cerebellar arteries supply?
- Cerebellum
- Brain stem
