Strokes Flashcards
Define stroke
The damaging or killing of brain cells starved of oxygen as a result of the blood supply to part of the brain being cut off
Define TIA
A stroke that recovers within 24 hours from the onset of symptoms
State possible locations from where the clot may have come from
- The clot may come from the carotid arteries, brain, heart, aorta, vertebral/basilar arteries
- In the heart, it may be due to atrial fibrillation, valvular disease/prosthetic valves, endocarditis
What might be the differential diagnosis for stoke in younger patients
- Younger patients are unlikely to have a stroke
- Those who have stroke symptoms may have vasculitis, sickle cell anaemia, cocaine
Describe the presentation of an anterior cerebral artery stroke
- Motor - contralateral
- Lower limb affected more than upper limb - medial homunculus more affected
- Initially flaccid paralysis, followed by spasticity (upper motor neuron signs) - spinal shock
- Sensory - contralateral
- Loss of all sensory modalities in the lower limb - cortical problem thus spinothalamic and dorsal column both affected
- Damage to paracentral lobules leads to loss of voluntary control of micturition
- Damage to corpus callosum can lead to split brain syndrome or alien hand syndrome
What is malignant MCA syndrome
- A main trunk occlusion causes considerable cerebral oedema - significant brain tissue damage
- Known as malignant MCA syndrome
- May lead to coma/death
- Sometimes part of skull taken away to relieve pressure inside the pressure due to the build-up of oedema
Describe the presentation of a middle cerebral artery stroke
- Motor - contralateral
- Upper limb and face affected more than lower limb - lateral homunculus more affected
- Initially flaccid paralysis, followed by spasticity (upper motor neuron signs) - spinal shock
- Sensory - contralateral
- Loss of all sensory modalities in the upper limb and face
Describe the difference in presentation between a proximal and distal MCA stroke
- An occlusion at the proximal end will affect lateral motor cortex as well as the internal capsule
- Therefore face, arm and leg will be affected as all motor fibres pass through internal capsule
- An occlusion distal to the lenticulostriate artery branches spares the internal capsule so only motor function in face and upper limb affected
Discuss the visual effects problem of MCA strokes
- Proximal occlusion of MCA leads to contralateral homonymous hemianopia
- More distal occlusion of the MCA may lead to contralateral homonymous superior or inferior quadrantanopia
Describe the symptoms associated with speech in MCA strokes
- Symptoms depend on dominant hemisphere and which branch of MCA is occluded
- If dominant hemisphere (most likely left) is affected:
- Global aphasia caused by main trunk occlusion
- Broca’s aphasia if branches towards Broca’s area infarcted
- Wernicke’s aphasia if branches towards Wernicke’s area infarcted
- If non-dominant hemisphere (most likely right) side is affected:
- Hemispatial neglect - neglect left side
- Tactile extinction - when touched simultaneous on left and right arm, patient will only notice right arm touched
- Visual extinction - when viewing object from both eyes, the left eye object is ignored
- Anosognosia - denies disability
Describe the presentation of posterior cerebral artery stroke
- Visual cortex symptoms
- Contralateral homonymous hemianopia with macular sparing - More likely to present without other symptoms than in MCA infarct (no sensory/motor symptoms)
Describe the difference in presentation of proximal and distal strokes of cerebellar arteries
- Proximal occlusion may cause brainstem and cerebellar signs
- Distal occlusion may cause cerebellar signs alone
Describe signs of brainstem damage
- Cranial nuclei reside in brainstem
- ‘Crossed deficits’
- Damage to ascending/descending tracts in the cerebral peduncle affects contralateral side of body
- Damage to cranial nerves or their nuclei give ipsilateral signs
- Eg. Infarct of right cerebellar arteries may cause right CN III nerve palsy
Describe symptoms of a distal basilar artery occlusion
- Bilateral occipital lobe infarction - blindness
- Bilateral thalamic infarction - anaesthetised (loss of sensory function)
- Bilateral midbrain infarction - motor effects such as CN III nerve palsy
Describe symptoms of a proximal basilar artery occlusion
- Locked-in syndrome
- An occlusion of the basilar artery at the pons level causes:
- Lose all CN function apart from CN I, II, III, IV - only able to move eyes
- Anaesthetised at all levels
- Full consciousness