10. Head trauma & acute intracranial events

Question 1

What is the difference between primary and secondary brain injury?

Answer 1

Primary: induced by mechanical force and occurs at moment of injury, e.g. axonal shearing.

Secondary: occurs some time after primary impact, not as a result of the trauma but of complications, e.g. hypoxia. intracranial hypertension. Can be attenuated or prevented by appropriate treatment.

Question 2

What are the 2 main types of primary brain trauma?

Answer 2

1. FOCAL
   
   • haematoma (extradural, subdural, intracerebral)
   • contusion (coup and countre-coup)
2. DIFFUSE
   
   • concussion
   • diffuse axonal injury

Question 3

What is cerebral contusion - how does it occur?

Answer 3

• “Bruising” of the brain (blood mixes with cortical tissue) due to microhaemorrhages caused by trauma.
• Often involve coup/contre-coup trauma where brain is injured directly under area of impact as well as opposite side (due to rebound against opposite cranial wall).

Question 4

Which parts of the brain are at particular risk of contusion?

Answer 4

Inferior frontal and temporal lobes due to collision with bony protuberances in middle cranial fossa and roof of ocular orbit - can cause attention, emotional and memory problems.

Question 5

What is concussion? What are the symptoms?

Answer 5

Head injury involving temporary loss of brain function due to stretching and injury to neuronal axons (mild form of DAI). Results in:

1. impaired neurotransmission
2. loss of ion regulation
3. reduction in cerebral blood flow

Symptoms usually appear mins-hrs post trauma:

1. persistent headache
2. dizziness
3. nausea and vomiting
4. confusion, loss of memory
5. vision problems
6. irritability, anxiety

Question 6

Describe a possible complication of concussion.

Answer 6

Post-concussion syndrome - set of symptoms that persist from weeks to a year or more after a concussion.

• Cognitive: difficulty thinking, concentrating and memorising
• Physical: headache, balance problems, dizziness, fatigue, vision problems
• Emotional: irritability, anxiety
• Sleep disturbance

Question 7

What is diffuse axonal injury? Why is this serious?

Answer 7

Shearing of interface between grey and white matter following traumatic acceleration/deceleration or rotational injuries to the brain, damaging the intra-cerebral axons and dendritic connections.

Frequently associated with cerebral oedema and RICP… risk of herniation… progression to coma and death.

Question 8

Name 4 signs of basilar skull fractures.

Answer 8

1. racoon eyes
2. CSF rhinorrhea or otorrhea
3. Battle sign
4. haemotympanum