Traumatic Brain Injury

Question 1

What is primary brain injury?

Answer 1

Direct trauma to the brain tissue

Question 2

Can primary brain injuries be reversed or treated?

Answer 2

No, because these are usually due to blunt/penetrating trauma

Question 3

What is secondary/delayed brain injury

Answer 3

This is brain injury that occurs gradually after initial injury

Question 4

What are common causes of secondary brain injury?

Answer 4

• ischemia
• hypoxia
• inflammation
• sodium potassium pump failure (leads to necrosis)
• cerebral edema
• increased intracranial pressure

Question 5

What is an open brain injury?

Answer 5

The scalp and skull are not intact and the brain may be exposed

Question 6

What are the after effects of brain injury?

Answer 6

• infection
• TBI-induced epilepsy

Question 7

Why is there an increased risk of spinal injuries from skull fractures?

Answer 7

This is due to the force transference from the skull into the spinal column

Question 8

Ischemia can occur rapidly after a brain injury leading to what…

Answer 8

Necrosis and extracellular edema

Question 9

How can rapid depolarization in an affected are of the brain be a mechanism of ischemia?

Answer 9

Rapid depolarization can disrupt ion movement, electrolyte balance, and blood perfusion which leads to ischemia

Question 10

How does a mechanical force like a bat to the head result in rapid depolarization leading to ischemia

Answer 10

It triggers mechanical receptors that lead to graded potentials and if sufficient it can lead to rapid large scale depolarizations

Question 11

What are the causes of cerebral edema?

Answer 11

• leaky capillaries
• necrosis
• sodium potassium pump failure
• calcium overload

Question 12

How does leaky capillaries cause cerebral edema?

Answer 12

The leaky capillaries is caused by inflammatory responses which increase capillary permeability which allows fluid to escape in surrounding tissue

Question 13

How does necrosis cause cerebral edema?

Answer 13

Necrosis results in the release of chemoreceptors and bring white blood cells to further increase permeability in the capillaries

Question 14

How does sodium potassium pump failure cause cerebral edema?

Answer 14

When the sodium potassium pump fails sodium accumulated inside the cell which water follows and causes the swelling

Question 15

How does calcium overload cause cerebral edema?

Answer 15

When the calcium pump fails, calcium pools within the cell causing damage to the mitochondria which leads to apoptosis/necrosis which results in the release of the chemoreceptors inviting white blood cells increasing permeability in the cappilaries

Question 16

What is a concussion?

Answer 16

A diffuse brain injury, meaning it affects a wide spread area primarily targeting axons which stretch and damage

Question 17

Why are concussions hard to diagnose?

Answer 17

Because they are invisible on CT scans and MRIs. Patients might also not show obvious symptoms

Question 18

A contusion is a bruise on the brain involving bleeding from vessels into surrounding tissues. What does this result in?

Answer 18

Localized swelling and tissue damage

Question 19

What is a focal brain injury?

Answer 19

A localized injury to the brain tissue at the site of impact

Question 20

What happens if there is a focal injury to the occipital lobe?

Answer 20

There could be visual disturbances

Question 21

What happens if there is a focal injury to the frontal lobe?

Answer 21

Symptoms like
- agitation
- poor decision making, memory issues, and concentration problems

Question 22

What is diffuse axonal injury? what is it caused by?

Answer 22

A widespread injury across the brain caused by the movement of the brain within the skull

Question 23

How is the brain able to mov around in the skull?

Answer 23

Due to Cerebral spinal fluid

Question 24

What could be the consequence of DAI?

Answer 24

Coma/vegetative state due to wide spread axonal damage

Question 25

What happens when axons are damaged?

Answer 25

Nerve impulses cannot be transmitted beyond the point of injury leading to loss of function in those regions. Once axons are damaged neurons can not connect properly

Question 26

Which part of the brain stem plays a major role in maintaining consciousness and alertness and will shift during traumatic impact?

Answer 26

The Reticular activating system (RAS)

Question 27

What is somthing to consider with regards to coma and recovery?

Answer 27

- recovery from an DAI is unlikely - cases involving inflammation may resolve as swelling decreases allowing some function to return

Question 28

What is the difference between a concussion and a contusion?

Answer 28

- Concussion involves axonal injury and wide spread (diffuse) - contusion involves vascular damage and localized (focal) - however both injuries can occur simultaneously

Question 29

What is depolarization without tearing, and how does it affect the brain function after a head injury?

Answer 29

This is when axons rapidly depolarize without structural damage causing temporary unconsciousness after a head injury

Question 30

What happens when axons are sheared,torn,twisted. How does it affect consciousness and what if the brain stem is involved?

Answer 30

- it leads to longer or permanent loss of consciousness. Ie. coma especially if the brain stem is involved as it regulates HR and breathing