Traumatic Brain Injury Flashcards
What is primary brain injury?
Direct trauma to the brain tissue
Can primary brain injuries be reversed or treated?
No, because these are usually due to blunt/penetrating trauma
What is secondary/delayed brain injury
This is brain injury that occurs gradually after initial injury
What are common causes of secondary brain injury?
- ischemia
- hypoxia
- inflammation
- sodium potassium pump failure (leads to necrosis)
- cerebral edema
- increased intracranial pressure
What is an open brain injury?
The scalp and skull are not intact and the brain may be exposed
What are the after effects of brain injury?
- infection
- TBI-induced epilepsy
Why is there an increased risk of spinal injuries from skull fractures?
This is due to the force transference from the skull into the spinal column
Ischemia can occur rapidly after a brain injury leading to what…
Necrosis and extracellular edema
How can rapid depolarization in an affected are of the brain be a mechanism of ischemia?
Rapid depolarization can disrupt ion movement, electrolyte balance, and blood perfusion which leads to ischemia
How does a mechanical force like a bat to the head result in rapid depolarization leading to ischemia
It triggers mechanical receptors that lead to graded potentials and if sufficient it can lead to rapid large scale depolarizations
What are the causes of cerebral edema?
- leaky capillaries
- necrosis
- sodium potassium pump failure
- calcium overload
How does leaky capillaries cause cerebral edema?
The leaky capillaries is caused by inflammatory responses which increase capillary permeability which allows fluid to escape in surrounding tissue
How does necrosis cause cerebral edema?
Necrosis results in the release of chemoreceptors and bring white blood cells to further increase permeability in the capillaries
How does sodium potassium pump failure cause cerebral edema?
When the sodium potassium pump fails sodium accumulated inside the cell which water follows and causes the swelling
How does calcium overload cause cerebral edema?
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
What is a concussion?
A diffuse brain injury, meaning it affects a wide spread area primarily targeting axons which stretch and damage
Why are concussions hard to diagnose?
Because they are invisible on CT scans and MRIs. Patients might also not show obvious symptoms
A contusion is a bruise on the brain involving bleeding from vessels into surrounding tissues. What does this result in?
Localized swelling and tissue damage
What is a focal brain injury?
A localized injury to the brain tissue at the site of impact
What happens if there is a focal injury to the occipital lobe?
There could be visual disturbances
What happens if there is a focal injury to the frontal lobe?
Symptoms like
- agitation
- poor decision making, memory issues, and concentration problems
What is diffuse axonal injury? what is it caused by?
A widespread injury across the brain caused by the movement of the brain within the skull
How is the brain able to mov around in the skull?
Due to Cerebral spinal fluid
What could be the consequence of DAI?
Coma/vegetative state due to wide spread axonal damage
What happens when axons are damaged?
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
Which part of the brain stem plays a major role in maintaining consciousness and alertness and will shift during traumatic impact?
The Reticular activating system (RAS)
What is somthing to consider with regards to coma and recovery?
- recovery from an DAI is unlikely
- cases involving inflammation may resolve as swelling decreases allowing some function to return
What is the difference between a concussion and a contusion?
- Concussion involves axonal injury and wide spread (diffuse)
- contusion involves vascular damage and localized (focal)
- however both injuries can occur simultaneously
What is depolarization without tearing, and how does it affect the brain function after a head injury?
This is when axons rapidly depolarize without structural damage causing temporary unconsciousness after a head injury
What happens when axons are sheared,torn,twisted. How does it affect consciousness and what if the brain stem is involved?
- it leads to longer or permanent loss of consciousness. Ie. coma especially if the brain stem is involved as it regulates HR and breathing
