L20 - Traumatic Brain Injury Flashcards
- Risk factors for head injury and markers of severity - Difference between primary and secondary brain injury. - Delivery of medical intervention affects latter - Understand complications of head injury - Importance of rehabilitation
State some examples of causes of Brain injury?
RTC (road traffic collisions) Falls Assaults Sports Injuries Firearms
What are risk factors for brain injury?
Alcohol. Recreational drugs. Young adults. Elderly. Younger children.
Define a primary brain injury?
The initial insult to the brain at the time of injury.
State some examples of primary brain injury?
- Bleeding within skull
- Contusions (bruising) of the brain tissue
- Contracoup injury
- Diffuse axonal injury
- Penetrating injury
What is a contracoup injury?
Coup injury
- occurs under site of impact with an object
Contracoup
- occurs on the side opposite the area that was hit
What is a diffuse axonal injury?
Result of traumatic shearing forces that occur when head is rapidly accelerated or decelerated.
- Immediate disconnection of axons
Describe an extradural haematoma
Convex, inwards.
Spread limited by dural adhesion to skull.
LIP LIKE
Describe a subdural haematoma
Area of increased density spreading around surface of cerebral hemisphere.
BANANA LIKE
Describe a secondary brain injury?
Occurs from insults to the brain after the initial injury.
- Hypoxia, hypovolaemia and cerebral oedema.
Define hypovolaemia?
Volume depletion.
Can be due to a loss of both salt and water or just a decrease in BV.
Describe what may occur in the presence of a brain oedema?
- Raise in ICP
- Cerebral herniation
- raised ICP may lead to hypoperfusion (inadequate delivery oxygen and nutrients) of brain
- may cause cerebral ischaemia
What causes an extradural haematoma?
Middle meningeal artery bleeds into extradural space.
Describe diffuse axonal injury?
- Results from widespread axonal shearing
- often no signs on inital CT head
- can result in raised ICP from swelling
Briefly state the different types of skull fractures?
Simple
Depressed
Basal fractures
- more difficult to see on X-ray
What particular physical signs are associated with Basal skull fractures?
Battle's sign, periorbital bruising. Produce bleeding into middle ear. CSF rhinorrhoea (clear fluid coming out of nose, contains glucose unlike mucus)
Describe penetrating trauma?
Damage occuring directly from object piercing skull and disrupting brain tissue.
State some causes that may lead to secondary brain injury?
Hypoxaemia
Hypotension
Raised ICP
During the pre-hospital care of a patient suffering a suspected brain injury it is important too…
Ensure adequate oxygenation and blood pressure to prevent hypoxic-ischaemic brain injury.
Describe what may occur during the pre-hospital care of a brain injury patient?
ABCDE assessment
Sedation, tracheal intubation with ventilation if GCS < 8
Control of bleeding
IV access and IV fluids / blood to maintain BP and cerebral perfusion.
Describe the Monro-Kellie
hypothesis
Sum of volumes of brain, CSF, and intracranial blood is constant.
Once skull reaches critical volume - any further expansion in the size of space-occupying lesions will result in a dramatic rise in ICP.
The pressure gradient driving blood flow to the brain is known as the…
Cerebral perfusion pressure CPP.
- often tightly controlled through autoregulation, despite variations in arterial BP.
Significant increases in ICP may result in…
Reduced CPP
- potentially causing further hypoxic-ischaemic damage
What is the formula for calculating cerebral perfusion pressure?
Mean arterial pressure - ICP
What are some signs of raised ICP?
Reduced conscious level.
Pupillary abnormalities e.g. dilation, bilateral ptosis.
Cushing’s triad
- late sign, often pre-terminal
What is Cushing’s triad?
- High BP
- Bradycardia
- Irregular breathing pattern
What two component’s can adapt most easily to accommodate an increase in the volume of intracranial contents?
Intracranial blood
- esp in the venous compartment
- CSF
Once these compensatory mechanisms are exhausted. further increases in vol result in large rises in ICP.
What are simple measures to help prevent / treat raised ICP?
Elevation of head of bed to 30 degrees
- improves jugular venous outflow, lowers ICP.
What is CVP?
- Central Venous Pressure
Circulating blood flows into the RA via inferior and superior vena cava.
Pressure in the right atrium is known as the central venous pressure.
Give an example of how Diuretics can be used to decrease ICP?
e. g. Mannitol
- intravascular osmotic agent, can draw fluid fro both normal and abnormal brain.
- decreased ICP through cerebral autoregulation,
Give examples of further treatment for raised ICP?
- Osmotic therapy
- Hyperventilation
- Sedation
- Craniectomy
How may Mannitol aid in decreasing a raised ICP?
Decreased blood viscosity
- resulting in reflex vasoconstriction and decreased cerebrovascular volume.
How may hyperventilation lead to a decreased ICP?
Reduced PaCO2
- vasoconstriction
- reduced ICP
Give problem with using hyperventilation to treat raised ICP?
Vasoconstriction can cause cerebral ischaemia therefore this is not generally recommended.
Once ICP of patient has stabilised what are the next steps?
Begin to withdraw sedation. Assess ventilatory needs. Assess neurological deficits. Other less acute injures via tertiary survey (e.g. broken fingers) Rehab
What are the categories of traumatic brain injury?
Mild / moderate / severe
What are the measures for severity of traumatic brain injury?
- Post traumatic amnesia
- Glasgow coma score
- <8 is very severe - Loss of consciousness
Describe post traumatic amnesia?
Reduced ability to lay down new memory.
Confusion, agitation, wandering of patient.
Requires supportive care.
Lasts from hours to months.
GOAT assessment helps identify improvements.
Frontal Lobe
Problem solving Emotional traits Reasoning (judgement) Speaking Voluntary motor activity
Temporal lobe
Understanding language
Behaviour
Memory
Hearing
Brainstem
Breathing Body temp Digestion Alertness / sleep Swallowing
Cerebellum
Balance
Coordination and control of voluntary movement
Fine muscle control
Occiptal lobe
Vision
Colour perception
Parietal lobe
involved in sensory Knowing right from left Sensation Reading Body orientation
How may the brain recover after injury?
Neurons do not regenerate. Neuroplasticity - brain can reorganise itself - new pathways develop - undamaged areas of brain take over from damaged areas
