TBI Flashcards
what is traumatic brain injury (TBI)?
external physical injury to brain caused by trauma to head after birth also called as concussion.
what kind of trauma takes place in TBI?
it has to be external physical force, not degenerative or congential nature
what is the function of following in a healthy individual?
- frontal
- parietal
- occipital
- temporal
- cerebellum
- brainstem
- frontal - concentration, problem solving, speech (PCS)
- parietal - sense of touch, pain, temperature (TPT)
- occipital - healthy vision
- temporal - memory + organisation
- cerebellum - balance + coordination
- brainstem - breathing, steady heart rate
how is the function impaired in these following regions of TBI individual?
- frontal
- parietal
- occipital
- temporal
- cerebellum
- brainstem
- frontal - lack of concentration, language difficulty, irritability
- parietal - difficulty with reading, spatial misperception
- occipital - blurred vision, blind spots
- temporal - short and long term memory impairment
- cerebellum - difficulty walking + slurred speech
- brainstem - changes in breath + difficulty swallowing
what are the types of TBI and its causes?
- open head injury caused by penetrating injury
2. closed head injury caused by blunt injury
what are the types of penetrating injury and blunt injury?
penetrating - gunshot wound, knife, fracture, hair/bone going into head
blunt - falling over, stroke(internal head injury)
when are the open head injuries fatal?
- severity depends on the areas affected
- if involvement and damage to both
1. hemispheres
2. ventricles
3. multiple lobes
4. brain stem
then they are usually fatal - if the person survived those areas then complete recovery with secondary symptoms
what are the two closed head injuries?
coup and contra coup
what is the difference between coup and contra coup?
Coup - occurs on the brain directly under the point of impact
Contra coup - occurs on the opposite side of brain from where the impact occurred
what are the characteristics of TBI?
bleeding, tearing and sheering
- subdural haematoma - bleeding under the dura matter
- white matter injury - axonal damage, twisting and tearing of brain inside the skull
- secondary change - changes in blood flow, oxygen levels and excitotoxic cell damage (inflammation)
what causes the secondary damage in TBI?
due to excessive tearing and shearing force, there is NTs leakage
which are the neurochemicals released in the leaky brain?
- glutamate
- chloride
- pottasium and sodium
what does the leaky brain result in?
- swelling and inflammation from tissue damage
- increasing the pressure resulting in more damage
how does the chilling the brain helpful?
- excess bleeding in brain -> pressure
- no drug can stop the Its leakage resulting in swelling of brain
- therefore, the brain undergoes hypothermia
- since neurons and glutamate are temperature sensitive and prefer high temperature
- the cold temperature slows down the process of injury and inflammation
what are the diagnostic imaging of TBI?
- x-ray - skulls damage
- CT scan - bleeding (first choice for TBI)
- MRI scan (functional/resting state)- changes in fluid
- EEG - faulty signalling (epileptic seizure)
- PET scan
- DTI - location of injury, areas affected, white matter tracts
what is second impact syndrome (SIS)?
- back to back concussions without time to heal
- when there is second head injury before the damage from the first injury has cleared or recovered
- rare but potentially serious
- life threatening condition
what is SIS result in?
results in loss of auto regulation of blood supply
- vascular engorgement
- increased intracranial pressure
- brain herniation (side effect of high pressure within skull)
- rapid brain stem failure
how do the brain cells die in SIS?
- Incapacity of the BV to dilate and conduct blood flow to those areas, damage to BV
- exacerbation of first injury
- individuals who survive usually have memory loss or develop dementia
what is the chronic traumatic encephalopathy (CTE)?
CTE is a secondary injury ; progressive degenerative brain disease, caused by repeated hits to the head
what is genetic background of CTE?
- Genetics and age of exposure can play a role
- CTE can only be diagnosed after death
- caused by the deposition of tau protein. in hippocampus (temporal lobe)
- The accumulation goes on for hyperphosorylated tau and it undergoes several stages
- also involved ApoE gene (associated with the risk of getting AD)
There is higher risk of developing of CTE for those with ApoE genotype?
A. True
B. False
A. True
what are the characteristics of dementia pugilistic/ boxing dementia?
- slurred speech (temporal lobe is affected)
- memory impairment and Parkinson like syndrome
- also called as punch drunk syndrome
- thought to be similar to CTE
what are the structural changes in brain in healthy and TBI/AD?
Healthy individuals - smoother surface of brain + chunkier gyrus
TBI/AD - gyrus and sulcus becomes prominent due to shrinkage of brain matter
what are the three stages for rate of cognitive decline?
- ageing only with no injury
- additive effects of age and injury
- synergetic effects of age and injury
what are the complex neurotoxic cascades after TBI secondary pathological insults?
- BBB disruption (due to disruption emotion)
- cerebral oedema
- ischemia (due to lack of oxygen)
- energy failure (due to lack of glucose)
- excitoxicity
- cell death cascade
what is the role of BBB?
astrocytes + capillary
what are the types of glia cell found in CNS and PNS?
CNS - 1. ependymyal cells 2. oligodendrocytes 3. astrocytes 4. microglia PNS - 1. satellite cells 2. Schwann cells
what is the gliovascular complex?
- BBB + astrocytes surrounding it and the receptors that go within that membrane TGBF, NTs
- Microglia is surrounding the gliovascular
- microglia decides what goes in and out
- In TBI whole complex gets disrupted
- The endothelial cells which shear apart for exposing areas that come in and out
what is astrogliosis?
- it is the abnormal increase in the number of astrocytes due to destruction of astrocytes
- Healthy astrocytes will turn into reactive astrocyte
- proliferate, migrate to point of injury and release cytokines and cytotoxins and form the glial scar
- load of astrocytes in the affected injury area and more of toxins are secreted as well
what are the insults that induces astrogliosis?
- IL-1beta
- TNF-alpha
- ROS
- oxidative stress
which gene is responsible for the astrocytes proliferation and migration?
astrocyte elevated gene -1
outline the steps of astrogliosis
- release of inflammatory cytokines like IL-1beta, TNF-alpha and ROS due to oxidative stress due to mild/severe tissue damage and cell death
- the release of this mediators activate healthy astrocytes into reactive astrogliosis
- injurer increases AEG-1 localisation to cytoplasm and nucleus of astrocytes
- the change is localisation of AEG-1 in astrocytes results in in increased proliferation and migration during reactive astrogliosis
what are the causes of destruction of neurons in astrogliosis?
CNS trauma, infection, neurodegenerative, injury etc