L18 - Brain Killers

Question 1

Causes of stroke (6)

Answer 1

o Brain artery blocks – most common

o Brain artery bleeds

o Poor general circulation

o Heart failure

o Drowning

o Low oxygen at birth

Question 2

The greedy brain facts 7

Answer 2

• 2-3% of body weight
• 15% of cardiac output
• 20% of all O2
• 25% of all glucose (primary source of energy)
• Brain critically dependent on a constant blood supply
• Blood brain barriers – tighter japs

Question 3

Stroke risk factors

Answer 3

• Atherosclerosis - Brain or body (debris)
• Age
• Diabetes (doubles the risk) - Type 2 particularly (undiagnosed)
• Ethnic origin (more common in African-Caribbean/SE Asian people) -High salt diets
• Excessive alcohol
• Family history of stroke (polygenetic)
• Heart disease
• High blood pressure
• High blood cholesterol (suggested – not strong evidence)
• Obesity & inactive lifestyle
• Smoking

Question 4

Stroke symptoms (6)

Answer 4

• Sudden severe headache
• Dizziness/sudden falls
• Speaking difficulty
• Dimness/loss of vision
• Weakness/numbness in face (one side of body)
• FAST

Question 5

Damage caused by a stroke 2

Answer 5

• Brain stack

• Every minute
o 2 million brain cell lost
o 14 billion connection gone

Question 6

Causes of ischaemic stroke

Answer 6

• Stroke is a vascular disease, but not necessarily a cerebrovascular disease

• 50%: athero-thrombo-embolism cerebral arterial supply
• 20%: embolism from heart
• 25%: intracranial small vessel disease
• 5%: rare causes (young people – maybe neck injury)

Question 7

Types of Stroke (2)

Answer 7

• Ischaemic Stroke - Vessel becomes blocked (most common)

* Haemorrhagic Stroke Vessel bursts (higher risk 50’s/60’s)

Question 8

Atherosclerosis (4)

Answer 8

• Fatty deposits
• Active cells - poring out toxic
• Stem can unblocked/Or bypassing

• Ischaemic damage
o Initial brain swelling
o Reduction in brain cells

Question 9

What is TPA and its function?

Answer 9

Breaks down clots (injected quickly/works very well)
o Used ¼ of cases – need to be sure it’s a clot
o Need CT scan
o Too late can be worse – can cause secondary bleeding
o Should be used within 3 hours of stoke / no more than 6 hours.

Question 10

Development of ischaemic damage (immediate and surrounding regions)

Answer 10

• Cells in immediate area - Die within minutes-hours

• Surrounding regions – lower opt level but potential to prevent damage
o Can damage surrounding areas but slower – Penumbra (vulnerable tissue) – damaged neurons release toxins and kill neighbours
• Blood supply compromised but not cut off
• Cells under “threat” but not dead
• Potential for rescue
• Must start treatment early

Question 11

Neuron Death – 3 categories

Answer 11

• Neurotransmitters
o Glutamate

• Ions
o Calcium, sodium

• Free radicals
o Abnormal oxygen molecules e.g. superoxide

Question 12

A cascade of events…

Answer 12

Excitotoxicity (Glutamate + Asparate release damage) > Peri-infarct depol (wild/uncontrollably) > inflammation > apoptosis

Question 13

Ischaemic cell death: mechanisms

Answer 13

Blood & Brain Cells
Damaged vessels let in substances that shouldn’t be in the brain
- Platelets and immune cells get in

Question 14

Reperfusion injury

Answer 14

• Restoration of blood flow to an area of the brain previously rendered ischaemic by a thrombotic blockade of a key artery
• Caused by lysis or dislodgement of the clot
• Results in inflammation and oxidative stress.

Significant in brain damage

Question 15

Post stroke disabilities

Answer 15

• Paralysis/motor control
• Sensory disturbance (pain)
• Language problems
• Memory impairment
• Depression/anxiety

Question 16

Reparative mechanisms

Answer 16

• Plasticity
o Better in young people
• Neurogenesis
• Angiogenesis