14.4 Head Injuries

Question 1

Mechanisms of traumatic brain injury

Answer 1

Penetrating
- Direct trauma to underlying parenchyma
- GSW creates a shokwave effect with cavitation effect (brain contained in skull – significant damage)

Blunt force
- Direct blunt force can fracture skull – transmit energy to brain tissue
- Depressed segments (extreme velocity) with injury
- Compound fractures (open skin) = high infection risk
- Fractures can cause vascular injury

Coup contre-coup
- Contra-lateral side injury (eg fall from height)
- Suspension in CSV can cause meningeal attachment tear on opposite side with continuous movement in suspension during stop

Question 2

Pathophysiology of Traumatic brain injury

Answer 2

Haemorrhage
- Subgaleal haematoma.
- Extradural haematoma
- Subdural haematoma
- Subarachnoid haematoma
- Interparenchymal bleed

Contusions
- Simmilar to a bruise
- Eg accelerationdecelerationinjury,witha rotational component, they might suffer from Diffuse Axonal Injury (shearing of axons in white matter

Secondary brain insult
- Damage being done due to changes secondary to the trauma
- Hypoxia, Hypovolaemia/Hypotension (decreased cerebral perfusion)
- Hyper or Hypocapnea (abnormal CO2 levels)

Monro-Kellie doctrine
- Sum of volumes of brain, CSF and intracerebral blood are constant
- Herniation = Sub-falcine, Tonsillar, Uncal, Transtentorial or Transcalvarial.

Question 3

Injury patterns of spinal cord injuries

Answer 3

Complete chord transection
- Complete motor fallout below the level of injury
- Level = ? paraplegic vs quadriplegic
- If sensory fallout below this level, in both spinothalamic tract and corticospinal tracts
- If level above the level of the phrenic nerve (C3/C4/C5) = no longer compatible with life as the patient will not be able to breathe, with all respiratory muscles and the diaphragm being denervated

Incomplete chord transection
- Pattern not always clear (eg polytrauma pt – intubated or unconscious
- Central chord syndrome
- Brown-Sequard syndrome

Slide 8-9

Question 4

Spinal VS neurogenic shock

Answer 4

Spinal
- Spinal cord concussion - in temporary physiological disruption of the cord function
- Flaccid paralysis and loss of reflexes, sustained priapism
- 30-60min after injury and can persist for up to 6 weeks

Neurogenic
- Type of distributive shock
- Seen in spinal cord injuries above the level of T6
- Anytime up to a few weeks post injury, and is usually a diagnosis of exclusion
- Result of interruption of sympathetic input from hypothalamus to the cardiovascular centre - subsequent unoppos vagal tone in the vascular smooth muscle resulting in vasodilatation and decreased systemic vascular resistance