1.11 Acute Insults to the CNS: Traumatic Brain Injury Flashcards
What is the biggest cause of death and disability (combined) in adults under 45?
Traumatic brain injury
What GCS corresponds to mild, moderate, and severe brain injury?
13-15: Mild
9-12: Moderate
3-8: Severe
What periods of unconsciousness correspond to what severity of TBI?
Mild: <30mins
Moderate: 30mins-24hrs
Severe: Over 24hrs
What periods of post-traumatic amnesia correspond to what severity of TBI?
Mild: Less than a day
Moderate: Days to a week
Severe: More than a week
Chronically, what pathologies is TBI associated with?
- Seizures
- Sleep disorders
- Neurodegenerative diseases
- Psychiatric disorders
Differentiate between focal vs diffuse TBI
Focal: one area of the brain
Diffuse: more than one area of the brain
Are primary/secondary TBI pathologies treatable?
- Primary can only be prevented by preventing the trauma in the first place
- Secondary can be treated, since it is occurring after the initial insult itself
What are some potential secondary consequences of traumatic brain injury?
- Neuroinflammation
- Cerebral oedema
- Oxidative stress
Summarise the pathology of penetrating TBIs
Laceration of brain tissue, crushing of brain tissue, intracerebral haematoma and ischaemia secondary to clotting.
Summarise the pathology of blast TBIs
Blast wave induces sudden increase in intracranial pressure, particularly at interfaces between CSF and brain. Results in penetration/cavitation of brain tissue, damage to blood vessels, and disruption of axonal pathways.
What causes focal brain injuries?
Object striking the head, or brain coming into contact with skull
Coup vs contrecoup injuries
Coup: At site of impact
Contrecopu: directly opposite
What are some downstream pathologies of focal TBI?
- Cranial fracture
- Intracranial haemorrhage
- Bruising
What is unique about TBIs at the base of the skull?
- Can cause tearing of meninges and leaking of CSF
- Can damage foramen of blood vessels/nerves
Describe the appearance of extradural haemorrhage on CT imaging
- Biconvex in shape (curve away from the skull)
- Limited by cranial sutures
Where is the most common site of an extradural haemorrhage?
- Pterion (pteron; Hermes)
- Point at which temporal, parietal, frontal, and sphenoid bones meet
Which of a subdural vs extradural haemorrhage worsens faster? Why?
- Extradural worsens faster
- Subdural is usually venous, so progresses slower than extradural, which is usually arterial
Which veins are commonly torn in subdural haemorrhage?
Bridging veins
Describe the imaging presentation of a subdural haemorrhage
Run with curvature of the brain.
Which has worse prognosis: subdural haemorrhage or extradural haemorrhage?
Subdural; associated with more brain injury
Cerebral contusions mech
- Brain comes into contact with irregular bony protuberances of skull
- Damages small blood vessels and other components of brain parenchyma
- Causes bruising (“contusions”); creating toxic environment that damages surrounding tissue
True or false: diffuse brain injury requires the brain to come into contact with the skull
False. It’s more likely to be axonal/vascular damage in response to acceleration/deceleration
Why is the brain particularly vulnerable to traumatic injury?
- Large weight relative to body
-High white:grey ratio (white is more vulnerable to damage) - Large size
What is the biggest cause of widespread axonal damage?
Secondary injury processes. Axotomy is actually quite rare.
