10.1.1 MCA Stroke

Question 1

What is a stroke?

Answer 1

Cerebral vascular incident, serious life threatening condition that occurs when blood supply to the brain is cut off

Question 2

What are TIAs?

Answer 2

Mini-strokes, completely resolve within 24 hours

Question 3

What are the different types of stroke?

Answer 3

Ischaemia (85%)
Haemorrhagic (10%)
Other (5%)

Question 4

What is an ischaemic stroke?

Answer 4

Thromboembolic

Question 5

What is a haemorrhagic stroke?

Answer 5

Intracerebral rupture of a vessel in the brain parenchyma
Subarachnoid

Question 6

What happens in other types of stroke?

Answer 6

Dissection- separation of walls of artery, can occlude branches

Venous sinus thrombosis- occlusion of veins causes back pressure and ischaemia due to reduced blood flow

Hypoxia brain injury- post cardiac arrest

Question 7

What is the emergency management of stroke?

Answer 7

Thrombolysis (if under 4 hours)
CT head to determine a bleed

Question 8

What acute imaging is used for strokes?

Answer 8

CT
- Ischaemic area of brain not visible early- as infarct becomes established will become hypodense

MRI
- Sometimes used
- Ischaemia shows up as a high signal area

Question 9

What are the classic stroke syndromes of an anterior cerebral artery infarct?

Answer 9

• Contralateral weakness in lower limb
• Lower limb affected more than upper limb
• Contralateral sensory changes in same pattern as motor deficits
• Urinary incontinence- paracentral lobules affected
• Apraxia- inability to complete motor planning (e.g. cannot dress even when power is normal)
• Dysarthria
• Alien hand syndrome

Question 10

Why do MCA strokes have such large effects?

Answer 10

MCA supplies large area of the brain

Question 11

What is the chance of mortality if the main trunk of the MCA is affected?

Answer 11

80%

Question 12

What are the 3 points the MCA can be occluded?

Answer 12

Proximally, before the lenticulostriates branch off

Lenticulostriate arteries

Distal branches

Question 13

If the proximal MCA is affected what happens?

Answer 13

All branches of the MCA will be affected leading to:
- Contralateral full hemiparesis
- Contralateral sensory loss
- Visual field defects
- Aphasia
- Contralateral neglect

Question 14

What causes contralateral full hemiparesis?

Answer 14

Internal capsule is affected which carries fibres to the face, arm and leg

About the internal capsule not the PMC

Question 15

What causes contralateral sensory loss?

Answer 15

Involvement of the primary sensory cortex

Question 16

What type of visual defects occur in MCA occlusions?

Answer 16

Contralateral homonymous hemianopia without macular sparing

Due to destruction of both superior and inferior optic radiations as they run through temporal and parietal lobes

More distal occlusions may affect one raidation alone, causing quadrantanopias

Question 17

What happens in aphasia in MCA occlusions/strokes?

Answer 17

Global aphasia if dominant hemisphere (usually left)

Unable to understand or articulate words

Question 18

What causes contralateral neglect?

Answer 18

Lesions of right parietal lobe

Question 19

What is contralateral neglect?

Answer 19

Issue with not ‘acknowledging’ that the usually left side of space or even your own body exists

Normal visual fields

Question 20

What are some other features of contralateral neglect?

Answer 20

Tactile extinction (if you touch each side simultaneously, won’t feel affected side)

Visual extinction (as with the clock)

Anosognosia (will not acknowledge they had a stroke, will confabulate to explain disabilities)

Question 21

What happens in lectiulostriate artery occlusion?

Answer 21

Destruction of small areas of internal capsule and basal ganglia

Does not cause cortical features- neglect or aphasia

Question 22

What are the different types of lenticulostriate strokes?

Answer 22

Pure motor
- Face, arm and leg affected equally
- Damage to motor fibres travelling through internal capsule

Pure sensory
- Face, arm and leg affected equally
- Damage to sensory fibres travelling through internal capsule- due to occlusion of thalamoperforator arteries, maybe lenticulostriates

Sensorimotor
- Mixed, caused by infarct occurring at boundary between motor and sensory fibres

Question 23

What does the superior division of the MCA supply?

Answer 23

Superior divison supplies lateral frontal lobe, primary motor cortex and Broca’s area

Question 24

What will happen in a superior division occlusion of the MCA?

Answer 24

Face and arm weakness and expressive aphasia if left hemisphere affected

Question 25

What does the inferior divison of the MCA supply?

Answer 25

Lateral parietal lobe and superior temporal lobe, primary sensory cortex, Wernicke’s area and both optic radiations

Question 26

What does an occlusion of the inferior divison of the MCA lead to?

Answer 26

Contralateral sensory change in face and arm

Receptive aphasia if left hemisphere

Contralateral visual defect without macular sparing- often homonymous hemianopia as both radiations damaged