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%) (thromboembolic)
- Haemmorhagic (10%) (intracerebral)
- 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?
infarct:
→ contralateral weakness of lower limb (much worse than face and upper limb)
→ contralateral sensory weakness similar to motor
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)
what are some ACA stroke presentations
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
Apraxia
Inability to complete motor planning. Often caused by damage to left frontal lobe
Dysarthria / aphasia
A very unusual sign in ACA infarcts compared with MCA infarct. frontal lobe damage
Split brain syndrome / alien hand syndrome (both rare)
Caused by involvement of corpus callosum which is normally supplied by the ACA
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?
lecticulo striate vessels involved
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:
→ all Branches effected,
- Lateral motor cortex – responsible for the conralateral face and arm
- Internal capsule – carries descending motor fibres from the entirety of the motor cortex (face, arm and leg may be affected), → contralateral sensory loss as the fibres pass down internal capsule
→ Contralateral homonymous hemianopia
→ can get left sided neglect of its on the right side
→ global aphasia ( combination of Brocas and wernickers) if on the left