Strokes

Question 1

Define stroke

Answer 1

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

Question 2

Define TIA

Answer 2

A stroke that recovers within 24 hours from the onset of symptoms

Question 3

State possible locations from where the clot may have come from

Answer 3

• 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

Question 4

What might be the differential diagnosis for stoke in younger patients

Answer 4

• Younger patients are unlikely to have a stroke

- Those who have stroke symptoms may have vasculitis, sickle cell anaemia, cocaine

Question 5

Describe the presentation of an anterior cerebral artery stroke

Answer 5

• 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

Question 6

What is malignant MCA syndrome

Answer 6

• 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

Question 7

Describe the presentation of a middle cerebral artery stroke

Answer 7

• 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

Question 8

Describe the difference in presentation between a proximal and distal MCA stroke

Answer 8

• 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

Question 9

Discuss the visual effects problem of MCA strokes

Answer 9

• Proximal occlusion of MCA leads to contralateral homonymous hemianopia
• More distal occlusion of the MCA may lead to contralateral homonymous superior or inferior quadrantanopia

Question 10

Describe the symptoms associated with speech in MCA strokes

Answer 10

• 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

Question 11

Describe the presentation of posterior cerebral artery stroke

Answer 11

• Visual cortex symptoms
  - Contralateral homonymous hemianopia with macular sparing
• More likely to present without other symptoms than in MCA infarct (no sensory/motor symptoms)

Question 12

Describe the difference in presentation of proximal and distal strokes of cerebellar arteries

Answer 12

• Proximal occlusion may cause brainstem and cerebellar signs
• Distal occlusion may cause cerebellar signs alone

Question 13

Describe signs of brainstem damage

Answer 13

• 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

Question 14

Describe symptoms of a distal basilar artery occlusion

Answer 14

• Bilateral occipital lobe infarction - blindness
• Bilateral thalamic infarction - anaesthetised (loss of sensory function)
• Bilateral midbrain infarction - motor effects such as CN III nerve palsy

Question 15

Describe symptoms of a proximal basilar artery occlusion

Answer 15

• 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

Question 16

Describe the presentation of a stroke affecting the lenticulostriate artery

Answer 16

• Supplies the posterior limb of the internal capsule which carries descending motor fibres to the entire body
• Patients present with pure motor hemiparesis
  
  • Contralateral
  • Paralysis - initially flaccid followed by spasticity)
  • Involves face, upper limb and lower limb

Question 17

Describe the presentation of a stroke affecting the thalamoperforator artery

Answer 17

• Supplies thalamocortical fibres - relays sensory information from the thalamus to the post-central gyrus (somatosensory cortex)
• Patients present with pure sensory stroke
  
  • Contralateral
  • Sensory loss of all modalities
    
    • Involved face, upper limb and lower limb

Question 18

Describe the oxford classification of strokes

Answer 18

• Total anterior circulation syndrome - proximal MCA or ICA pcclusion
• Partial anterior circulation syndrome - MCA branch occlusion
• Posterior circulation syndrome - vertebral, basilar, cerebellar or PCA occlusion
• Lacunar syndrome - - lenticulostriate, thalamoperforator occlusion

Question 19

Describe the imaging of strokes

Answer 19

• In the acute phase, the most important thing is to look for bleeding - CT scan sufficient
  
  • Although MRI provides better quality imaging and shows damage to tissue, it takes more time therefore CT preferred acutely
• Early parenchymal changes (>1 hr) - grey matter becomes hypodense (dark) and there is a loss of grey/white matter differentiation

Question 20

Describe the types of lacunar strokes

Answer 20

• Pure motor stroke - lenticulostriate artery affecting the motor aspect of the internal capsule
• Pure sensory stroke - thalamoperforator artery affecting the thalamocortical fibres of the internal capsule
• Sensorimotor stroke - stroke affecting both the sensory and motor portions of the internal capsule