What are the possible consequences of concussion?
- Instantaneous loss of consciousness
- Temporary respiratory arrest
- Loss of reflexes
Which system is suggested to be involved in concussion?
Reticular activating system
How will the brain be affected by a penetrating injury compared to a closed injury?
Penetrating injury leads to direct disruption of tissue.
Closed injury leads to movement and compression of neural and vascular structures within the bony confines.
What are the potential secondary effects of traumatic injury to the brain?
Cerebral swelling (raised ICP)
Why are skull fractures important to diagnose?
Because they are an indicator of a high energy transfer injury.
What determines if a skull fracture is open or closed?
If it communicates with the surface.
What is a comminuted fracture?
A fracture involving the splintering of bone.
What does blood/CSF from the nose and/or ears suggest?
Which artery is most commonly associated with epi- and extra-dural haematomas?
Middle meningeal artery
Which vessels are most commonly associated with subdural haematomas?
Why can an extradural haematoma rapidly kill?
When involving the middle meningeal artery, the high pressure of the artery means that blood will quickly extrude into the potential space between the dura and bone.
Pressure must be relieved or the patient will die.
Why are extradural haematomas particularly prevalent in the younger population?
Because the dura has not completely adhered to the skull
Why do subdural haematomas take longer to present?
Because it's a lower pressure bleed situation involving the subdural veins.
Why are the elderly particularly susceptible to subdural haematomas?
Veins draining from the brain into venous sinuses in the dura become stretched as the brain gradually contracts with age, making them more susceptible to traumatic rupture.
What con contusions lead to?
What is a coup injury?
The injury to the brain directly underlying the site of impact.
What is a contrecoup injury?
The injury to the side of the brain directly opposite the site of impact.
Where do stereotypic contusions tend to occur?
At the base of the brain (e.g. inferior frontal lobes, inferolateral temporal lobes)
What is likely to be present in a severe or multifocal brain injury?
A lot of sub-arachnoid haemorrhage.
What is likely to be present in a patient who has survived cerebral contusions?
Parts of the gyri will collapse and fold down.
With the passage of time, macrophages take away the damaged tissue and cerebral blood, leaving orange staining.
The brain doesn’t heal itself; it leaves an area of scarring and is a particularly distinctive injury, being at the tips of the gyri.
What is the difference between a contusion and a haematoma?
Haematoma is bleeding into the brain resulting in a pocket of blood, whereas a contusion is the soft tissue damage resulting in a bleed.
What is a laceration?
Penetration by a foreign body or skull fragments.
Which part of the brain is particularly susceptible to diffuse forms of brain injury?
What is diffuse axonal injury?
Injury resulting from traumatic brain injury from, for example, severe deceleration.
Instead of a focal site of damage, small blood vessels will have torn, resulting in damage to axons throughout the tracts of the brian.
What is seen microscopically in diffuse axonal injury?
Axonal spheroids: areas where there's a buildup of things being shuttled up and down the axon.
These are swellings and an indicator of axonal injury.
What will happen to the brain if the patient survives diffuse axonal injury?
Atrophy will occur, ventricles will enlarge, thinner corpus collosum (due to damage and subsequent removal of tissue).
Relatively thin white matter in general compared to the amount of cortical tissue present
True or false: the principles of brain injury remain the same for the spinal cord?
The principles remain the same (other than the clinical manifestations being different)
Why will there be further injury to the spinal cord other than the site of initial damge in a vertebral fracture?
Because the cord is compressed, leading to a "toothpaste" effect.
The cord tissue is squeezed proximally and distally in both directions, leading to further potential injury.
What are 4 potential longer term sequelae of brain trauma?
- Chronic traumatic encephalopathy
What can cause chronic traumatic encephalopathy?
Brain atrophy due to neuronal loss
Abnormal deposition of Tau protein
Often diffuse deposition of a-beta plaques in cortex
What is the volume of CSF and blood in the cranium?
150ml of each
What is the initial response to an expanding brain lesion?
Expulsion of as much CSF and venous blood as possible.
When will brain perfusion cease?
When ICP approaches arterial pressure.
What are the potential causes of raised ICP?
Overproduction, obstruction to flow or absorption of CSF
What are the 2 main subtypes of cerebral oedema?
Vasogenic and cytotoxic
What is vasogenic cerebral oedema?
Blood-brain barrier disruption with increased vascular permeability.
What does vasogenic cerebral oedema predominantly involve?
What is vasogenic cerebral oedema responsive to?
Steroids and isotonic pressure manipulations and hypocardia-inducing therapies
What is cytotoxic cerebral oedema?
Increased intracellular fluid secondary to neuronal, glial or endothelial cell membrane injury.
What type of cerebral oedema occurs in strokes and infarcts?
Cytotoxic cerebral oedema
Which tissue types does cytotoxic cerebral oedema affect?
Grey and white matter
True or false: cytotoxic cerebral oedema responds to steroids.
Which of the two cerebral oedema subtypes is treatable?
Vasogenic cerebral oedema
What are the major sites of CSF block?
- Foramen of Monro
- Third ventricle
- Aqueduct of Sylvius
- Foramina of Luschka and Magendie
- Basal cisterns/subarachnoid spaces
What is transtentorial herniation?
A bulge of brain tissue out of the cranium through the tentorial notch, caused by increased intracranial pressure
What is subfalcine herniation?
Displacement of the brain (typically the cingulate gyrus) beneath the free edge of the falx cerebri due to raised intracranial pressure.