Traumatic Brain Injury Flashcards
What is a primary brain injury?
Injury that occurs at moment of impact. They are not treatable.
What is a secondary brain injury?
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
Describe ways primary brain injuries can turn into secondary brain injuries?
- 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
What is the early management of head injuries?
Assess and identify if patient is at risk of secondary brain injury. Then do pre-emptive CT scan.
Using the monro-kellie doctrine for intracranial compensation for expanding mass
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
What is herniation and what are the clinical signs?
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
When should you think about sending a patient with a head injury to hospital?
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.
Describe the different sections of the Glasgow coma scale
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.
Describe how the GCS indicated the degree of head injury
15 - minimal (no history of loss of consciousness),
13-15 -mild,
9-12 - moderate,
8 or less - severe, need to intubate.
When should you request a CT scan?
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
What are some red flags of traumatic head injuries?
- 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.
Describe the affects of oxygen on cerebral blood flow?
Cerebral blood flow remains steady until the PaO2 drops below 50mmHg/7kPa of oxygen. Then it will exponentially increase.
Describe the effects of carbon dioxide on cerebral blood flow.
Increase in PaC02 causes an increase in CBF. So aim to keep PaC02 between 4.5-5.0kPa
What can you use to treat convulsions?
Phenytoin
How can you reduce the oxygen demand of the brain?
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.
How is cerebral perfusion pressure calculated?
Mean arterial BP (Diastolic pressure - 1/3 of pulse pressure) - Intracranial BP
Normal cerebral autoregulation maintains a constant blood flow of what?
50mmHg and 150mmHg
After a severe brain injury, what pressure do you want to maintain the; cerebral perfusion pressure, the systolic blood pressure and the intracranial pressure?
CPP - above 60-70mmHg.
Systolic BP - Higher than 90mmHG but preferably higher than 120mmHG.
ICP less than 20mmHG
What should you do if patient is hypotensive?
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!
How can you encourage venous drainage from head?
Nurse tilt up between 15 and 30 degrees.
What factors can suggest a risk on an intracranial mass?
- 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
What are the following signs?
peri-orbital brusing (anterior cranial fossa fracture) and battle’s sign (petrous temporal bone fracture)
What does this head CT show? INSERT IMAGE
Extradural haematoma. These are relatively uncommon and are strongly associated with skull fracture. Can have good outcome if treated
What does this head CT show? INSERT IMAGE
Subdural haematoma. Cresent shape. Common and occurs if there is rupture of the veins from the brain surface to the sagittal sinus. Worse prognosis
What does this head CT show?
Subarachnoid haemorrhage. Associated with ruptured aneurysm. It is more commonly caused by head injury
What does this head CT show?
Intracerebral haemorrhage. This occurs due to a stretching and shearing injury. Impact on side of the skull
What is important information to discuss with neurosurgeons?
Mechanism of injury, age, respiratory and CV status, GCS and pupil response, alcohol/drugs, associated injury and results of CT scan
What can temporaily reduce the CBF and ‘buy time’?
Temporary hyperventilation as this can decrease ICP
How can you reduce oedema in the brain?
Drug such as mannitol as it decreases blood viscosity. hypertonic saline and tranexamic acid.
