Stroke

Question 1

Define stroke

Answer 1

A serious life-threatening condition that occurs when the blood supply to part of the brain is cut off. Signs and symptoms must persist for more than 24hrs.

Question 2

What are the 3 broad categories of stroke?

Answer 2

Ischaemic stroke (85%) 
Haemmorhagic stroke (10%)
Other (5%) - eg dissection, venous sinus thrombosis...

Question 3

What symptoms are associated with an anterior cerebral infarct?

Answer 3

I’M SAD

1. Incontinence
2. Motor/sensory weakness or change
3. Split brain syndrome (involvement of corpus callosum)
4. Apraxia (inability to completemotor planning, often due to left frontal lobe damage)
5. Dysarthria / aphasia (more common in MCA infarcts)

Question 4

Where can the MCA be occluded?

Answer 4

3 main points:

1. Proximal in the main stem before the lenticulostriate arteries come off
2. Within the lenticulostriate arteries
3. In the distal branches of the MCA - superior or inferior division.

Question 5

Describe the effects of a proximal MCA occlusion.

Answer 5

All MCA branches affected

1. Contralateral full hemiparesis of face arm and leg (internal capsule)
2. Contralateral sensory loss (same regions)
3. Visual field defects
4. Aphasia (if left hemisphere affected)
5. Contralateral neglect (right parietal lobe involvement)

Question 6

What visual field defects are associated with a proximal MCA occlusion?

Answer 6

Contralateral homonymous hemianopia without macular sparing - due to destruction of sup/ inf optic radiations as they run through temporal and parietal lobes.
More distal occlusions may only affect one radiation - leading to quadrantanopias.

Question 7

What is anosognosia? What condition can it occur in?

Answer 7

Occurs in contralateral neglect. Is the phenomenon where the patient literally does not / cannot acknowledge that they have had a stroke. ‘lack of insight’

Question 8

Describe the effects of occlusion of the lenticulostriate arteries.

Answer 8

Lacunar stroke - destory small areas of internal capsule and basal ganglia.
Similar effects to proximal MCA infarct except they DO NOT cause cortical features.
Can be pure motor, pure sensory, or sensorimotor.
These effects result from damage to motor /sensory / both fibres as they run through the internal capsule.

Question 9

Describe the effects of a distal MCA occlusion.

Answer 9

1. Superior division - supplies lateral frontal lobe.
   a. Primary motor cortex = weakness in face and arm
   b. Broca’s area = expressive aphasia (if on left)
2. Inferior division - supplies lateral parietal lobe, and superior temporal lobe
   a. Primary sensory cortex = changes in sensory innervation to face and arWm
   b. Wernicke’s area = receptive aphasia
   c. Both optic radiations = often homonymous hemianopia without macular sparing

Question 10

What are the symptoms associated with occlusion of the posterior cerebral artery?

Answer 10

Contralateral homonymous hemianopia - with macular sparing due to collateral supply from the MCA
Contralatera sensory loss due to damage to thalamus

Question 11

Describe the symptoms of a cerebellar infarct.

Answer 11

Nausea
Vomiting
Headache
Vertigo/ dizziness

Question 12

Describe the signs of a cerebellar infarct

Answer 12

Ipsilateral signs = DANISH
Dysdiadochokinesia
Ataxia
Nystagmus
Intention tremor
Slurred speech (dysarthria) 
Hypotonia

(may also get ipsilateral brainstem signs, contralateral sensory deficits, or ipsilateral horners. This is because cerebellar arters supply brainstem as they loop around cerebellum)

Question 13

(HARD) Explain why a typical feature of brainstem strokes is contralateral limb weakness with ipsilateral cranial nerve signs.

Answer 13

Damage to corticospinal tracts above the decussation of medullary pyramids = contralateral limb wekaness.
On top of … Damage to cranial nerve nuclei on the same side.

Question 14

What is seen in occlusion of the distal basilar artery?

Answer 14

1. Visual and Occulomotor deficits (basilar send some branches to midbrain which contains occulomotor nuclei EDW)
2. Behavioural abnormalities
3. ABSENT motor dysfunction (cerebral peduncles can get blood from PCAs via the posterior communicating arteries)
4. Hallucinations and dream-like behaviour (role of brainstem in sleep regulation)

Question 15

What is seen in occlusion of the proximal basilar artery?

Answer 15

Can cause ‘locked in syndrome’ = loss of movement of limbs, but ocular movement and consciousness preserved.
Eyes still move because midbrain still receiving blood supply via posterior commmunicating arteries.