Acquired brain injury

Question 1

What is Acquired Brain Injury (ABI)?

Answer 1

all types of brain injury that occured after birth

Question 2

The brain can be injured as a result of:

Answer 2

• traumatic brain injury (TBI)
• stroke
• brain tumour
• poisoning
• infection and disease
• near drowning or other anoxic episodes
• alcohol and drug abuse

Question 3

Traumatic brain injuries

Answer 3

“a traumatically induced structural injury and/or physiologic disruption of brain function as a result of an external force”

• > 2/3 due to motor vehicle accidents
• > 2/3 involve young people aged 16 - 24 years
• 2/3 of those injured will be males.

Question 4

Traumatic brain injuries

Clinical signs:

Answer 4

• Any period of loss, or a decreased level, of consciousness
• Any loss of memory for events immediately before or after the injury
• Any alteration in mental state at the time of injury (confusion, slowed thinking etc)
• Neurologic deficits (weakness, balance, visual, speech, general sensory)

Question 5

TBI

Classification Schemes

Answer 5

Physical mechanism
Symptoms / severity
Pathoanatomy
Focal or diffuse
Primary or secondary

Question 6

Pathologic features of traumatic brain injury

- Primary TBI

Answer 6

Focal, multifocal or diffuse
1. Axonal injury
2. Vascular injury
o Subarachnoid haemorrhage
o Subdural haemorrhage
o Epidural haemorrhage
o Intracerebral / Parenchymal haemorrhage
3. Contusion - rupture of blood capillaries
4. Laceration - cut or tear

Question 7

Pathologic features of traumatic brain injury

Secondary TBI

Answer 7

Focal, multifocal or diffuse
• Ischaemic – hypoxic damage
• Brain swelling – congestion / oedema
• Raised intracranial pressure
• Neuroinflammation
• Infection

Question 8

Diffuse Axonal Injury (DAI)

Answer 8

Diffuse white matter damage is associated with a large proportion of patients with poor neurological outcome

Axons vulnerable due to their:
• Viscoelasticity: rapid deformation > brittle response
• High degree of alignment in tracts

unrestricted head movement after impact > rotational acceleration
> tissue deformation
> axonal tension (oblique)

rapid strain rate increases brittle behaviour -6/7% before fail

Question 9

Diffuse Axonal Injury (DAI) - 2

Answer 9

• Rapid (< 50 ms) tensile stretch of axons
> Damage axonal cytoskeleton
> Loss of elasticity > axonal undulation & misalignment
* Mechanical damage to sodium channels
> massive sodium influx
> axonal swelling
> triggers Calcium influx
> Calcium activates proteolysis further damaging cytoskeleton

• breakage of axons > secondary damage to cytoskeleton

Question 10

Diffuse Axonal Injury (DAI) - 3

Answer 10

> Impaired axonal transport mechanisms

> Accumulation of proteins in axonal swellings > secondary axotomy

Question 11

Haemorrhages & haematomas

Answer 11

Result from tearing of blood vessels at the time of injury

Question 12

Epidural haemorrhage

Answer 12

related to linear impact on side of skull > fracture > artery - blood loss>
pressure strips dura of brain

1. arterial injury, usually in middle meningeal artery
2. associated with temporal bone or other skull fractures
3. biconvex, lenticular shape; blood is contained by dural sutures
4. surgical emergency

push of cerebral hemisphere across
- put drill in and drain it

Question 13

Subdural haemorrhage

Answer 13

trauma, child abuse/shaken baby syndrome

1. venous injury to bridging cortical veins
2. skull fracture may not be present
3. usually crescentic in shape and not contained by sutures; it does not cross falx or tentorium
4. is found in trauma patients, older patients, and child abuse victims.

Question 14

subarachnoid haemorrhage

Answer 14

1. blood is in subarachnoid, hyperdensity is in CSF spaces
2. Aneurysm rupture or post-taumatic superficial cortical contusions are the cause
3. Vasospasm several days afterward may lead to secondary infraction.

Question 15

Cerebral parenchymal haemorrhage

Answer 15

Haemorrhage of small arterioles & capillaries in brain parenchyma
“parenchyma” = the bulk of a substance