Clinical Management of TBI

Question 1

Define primary brain injury and its treatment

Answer 1

refers to the sudden and profound injury that is complete at the time of impact

no treatment

Question 2

Define secondary brain injury and treatment

Answer 2

refers to the changes that evolve over a period of hours-days after the primary brain injury that contribute to further destruction of brain tissue. It is treated with medical intervention to minimise brain injury.

• optimise oxygenation
• optimise cerebral perfusion
• blood glucose
• hypo/hypercapnia (CO2)
• body temperature
• monitor ABGs

Question 3

What are the processes that occur during the stages of secondary brain injury?

Answer 3

• neurotransmitter release (glutamate)
• free radical generation
• calcium mediated damage
• inflammatory response
• mitochondrial dysfunction
• early gene activation

Question 4

Explain the Monroe-Kellie Doctrine

Answer 4

Describes the relationship between contents of the cranium and ICP.

Normally there are 3 volumes that exist in the cranium in equilibrium: blood, brain parenchyma and CSF. Due to the fixed nature of the skull this means an increase in any of these volumes results in an increase in ICP.

Pathology can cause this equilibrium to be disrupted eg. tumour. Initially when the tumour is small the volume of the new component can be small enough for the brain to compensate and compensatory mechanisms can be used to maintain a normal ICP (increased drainage of blood/CSF from the cranial cavity to create space).

Question 5

What is the early management of a head injury?

Answer 5

Assess GCS and identify if the patient is at risk of a secondary brain injury.

Do a CT scan if:

• GCS <13 on initial assessment in A and E
• GCS <15 2 hours after injury
• Suspected open/depressed skull or basal skull fracture
• Seizure
• 1 or more episodes of vomiting (3 in children)
• Amnesia for events more than 30mins before impact

Question 6

Describe the components of the Glasgow Coma Scale

Answer 6

Eye opening: 4- spontaneous, 3- to speech, 2- to pain, 1- don’t open, NT - unable to (eg. bandages/swelling)

Verbal: 5- orientated, 4- confused, 3- inappropriate, 2- incomprehensible, 1-no response, NT- dysphasic, T - intubated

Motor: 6- obeys commands, 5- localises to central pain, 4- normal flexion, 3-abnormal flexion, 2-extension, 1-no response

Question 7

Explain the scoring of the Glasgow Coma Scale in the context of a head injury

Answer 7

• Minimal injury: 15 (and no LOC)
• Mild: 13-15
• Moderate: 9-12
• Severe: 8 or less (requires intubation)

Question 8

What are the red flags for a head injury?

Answer 8

• LOC, drowsiness, confusion, fits
• painful headaches that don’t settle, vomiting, visual disturbance
• clear fluid from ear/nose, bleeding from ears, new deafness
• problems understanding or speaking, loss of balance, difficulty walking/weakness in limbs

Question 9

Describe some of the possible consequences of a brain injury

Answer 9

• convulsions
• increase in brain metabolic rate to increased temperature
• peri-orbital bruising
• Battle’s sign
• extra-dural haematoma
• sub-dural haematoma
• intracerebral haemorrhage

Question 10

How is CPP calculated?

Answer 10

MAP (diastolic pressure + 1/3 pulse pressure) - ICP

Question 11

What are the clinical signs of herniation of the brain?

Answer 11

• dilated or unreactive pupils
• extensor posturing (involuntary extensor positioning of the arms, flexions of hands, knee extension and plantar extension)
• decrease in GCS of 2 points or more

Question 12

What drugs treat hypercapnia?

Answer 12

• mannitol
• hypertonic saline
• tranexamic acid