Traumatic Brain Injury

Question 1

What is a primary brain injury?

Answer 1

Injury that occurs at moment of impact. They are not treatable.

Question 2

What is a secondary brain injury?

Answer 2

Injury that occurs due to secondary processes which occur at the cell and molecular level to exacerbate neurological damage. Can be due to neurotransmitter release, free radicle generation, calcium mediated damage, inflammatory response, mitochondrial dysfunction or early gene activation

Question 3

Describe ways primary brain injuries can turn into secondary brain injuries?

Answer 3

• Activation of biomolecular mediators of injury, which leads to neuronal damage and then cytotoxic oedema. Can also occur when there is cerebral vessel damage resulting in the opening of the BBB and increased interstitial fluid and tissue pressure and vasogenic oedema

Question 4

What is the early management of head injuries?

Answer 4

Assess and identify if patient is at risk of secondary brain injury. Then do pre-emptive CT scan.

Question 5

Using the monro-kellie doctrine for intracranial compensation for expanding mass

Answer 5

Where there is the introduction of a mass into the brain, compensatory mechanism occurs to prevent an increase in intracranial pressure, this occurs by loosing CSF and venous blood. However if the mass becomes too big then the compensatory mechanism can become exhausted leading to a rise in intracranial pressure

Question 6

What is herniation and what are the clinical signs?

Answer 6

If the intracranial pressure continues to rise to the point where the brain parenchyma will shift in position and become displaced. Signs are - dilated or unreactive pupils, extensor posturing or a decrease of 2 or more GCS points

Question 7

When should you think about sending a patient with a head injury to hospital?

Answer 7

If they are of extreme ages (under 5 or over 65.) if there is amnesia for events before or after injury, if there has been any loss of consciousness, if it was a high energy injury, if they have vomited (3 times in a child before hospitalization), seizure or previous neurosurgery or a bleeding/clotting disorder.

Question 8

Describe the different sections of the Glasgow coma scale

Answer 8

4 Eyes response - Score 4 if eyes open spontaneously, 3 if open to speech, 2 if open to pain, 1 if eyes do not open and NT if patient is unable to open eyes due to swelling or bandages.
5 (V) Verbal response - 5 if orientated, 4 if confused, 3 if inappropriate words, 2 if incomprehensible sounds, 1 if no response despite verbal and physical stimuli. NT if dysphasic, T if intubated.
M6 Motor response - 6 if obeys commands, 5 if localizes pain, 4 normal flexion towards stimuli, 3 if abnormal flexion, 2 extension to pain and 1 if no response to stimuli.

Question 9

Describe how the GCS indicated the degree of head injury

Answer 9

15 - minimal (no history of loss of consciousness),
13-15 -mild,
9-12 - moderate,
8 or less - severe, need to intubate.

Question 10

When should you request a CT scan?

Answer 10

If GCS <13 on initial assessment in A&E. If GCS is <15 2 hours after injury, if suspected open of depressed skull fracture, any sign of basal skull fracture, post traumatic seizure, 1 or more episodes of vomiting (3 in kids) and amnesia for evens 30mins before impact

Question 11

What are some red flags of traumatic head injuries?

Answer 11

• Loss of consciousness, drowsiness, confusion or fits.
• Painful headache which doesn’t settle, vomiting or visual disturbance.
• Clear fluid from ear or nose, bleeding from ears or new deafness.
• Problems understanding or speaking, loss of balance, difficulty walking or weakness in arms or legs.

Question 12

Describe the affects of oxygen on cerebral blood flow?

Answer 12

Cerebral blood flow remains steady until the PaO2 drops below 50mmHg/7kPa of oxygen. Then it will exponentially increase.

Question 13

Describe the effects of carbon dioxide on cerebral blood flow.

Answer 13

Increase in PaC02 causes an increase in CBF. So aim to keep PaC02 between 4.5-5.0kPa

Question 14

What can you use to treat convulsions?

Answer 14

Phenytoin

Question 15

How can you reduce the oxygen demand of the brain?

Answer 15

Treat pyrexia, as an increase in temp causes and increase in brain metabolic rate. Also think about sedating patient using propofol/midazolam as this will reduce oxygen demands.

Question 16

How is cerebral perfusion pressure calculated?

Answer 16

Mean arterial BP (Diastolic pressure - 1/3 of pulse pressure) - Intracranial BP

Question 17

Normal cerebral autoregulation maintains a constant blood flow of what?

Answer 17

50mmHg and 150mmHg

Question 18

After a severe brain injury, what pressure do you want to maintain the; cerebral perfusion pressure, the systolic blood pressure and the intracranial pressure?

Answer 18

CPP - above 60-70mmHg.
Systolic BP - Higher than 90mmHG but preferably higher than 120mmHG.
ICP less than 20mmHG

Question 19

What should you do if patient is hypotensive?

Answer 19

Look for another cause because head injuries are likely to cause such an increase in blood loss that would cause a patient to be hypotensive. Therefore look for chest trauma or pelvic fracture. Stop the bleeding and give fluids!

Question 20

How can you encourage venous drainage from head?

Answer 20

Nurse tilt up between 15 and 30 degrees.

Question 21

What factors can suggest a risk on an intracranial mass?

Answer 21

• High intensity injury, significant retrograde amnesia, history of coagulopathy, post traumatic seizure. GCS of 12 or less. GCS of 14/13 and failing to improve within 2 hours or clinical signs of skull fracture

Question 22

What are the following signs?

Answer 22

peri-orbital brusing (anterior cranial fossa fracture) and battle’s sign (petrous temporal bone fracture)

Question 23

What does this head CT show? INSERT IMAGE

Answer 23

Extradural haematoma. These are relatively uncommon and are strongly associated with skull fracture. Can have good outcome if treated

Question 24

What does this head CT show? INSERT IMAGE

Answer 24

Subdural haematoma. Cresent shape. Common and occurs if there is rupture of the veins from the brain surface to the sagittal sinus. Worse prognosis

Question 25

What does this head CT show?

Answer 25

Subarachnoid haemorrhage. Associated with ruptured aneurysm. It is more commonly caused by head injury

Question 26

What does this head CT show?

Answer 26

Intracerebral haemorrhage. This occurs due to a stretching and shearing injury. Impact on side of the skull

Question 27

What is important information to discuss with neurosurgeons?

Answer 27

Mechanism of injury, age, respiratory and CV status, GCS and pupil response, alcohol/drugs, associated injury and results of CT scan

Question 28

What can temporaily reduce the CBF and ‘buy time’?

Answer 28

Temporary hyperventilation as this can decrease ICP

Question 29

How can you reduce oedema in the brain?

Answer 29

Drug such as mannitol as it decreases blood viscosity. hypertonic saline and tranexamic acid.