Trauma Flashcards
What is a penetrating (missile) injury
When an object travels through the head to cause injury
Can be at high or low velocity
What are the effects of a penetrating (missile) injury
Focal damage - affects region the object strikes
Lacerations in the brain
Haemorrhage
What is cavitation
Where a high velocity object causes low pressure
Leads to short term cavity forming which then collapses causing damage
Describe high vs low velocity penetrating head injury’s
The speed an missile is travelling when it hits the head often determines the extent of the damage
Fast moving projectiles often cause more damage
Important in gun shot wounds
What is a non-missile (blunt) injury
When there is a sudden acceleration/deceleration of the head
Brain moves within the cranial cavity and makes contact with the inside of the skull
What are the common causes of blunt/ non-missile injury
RTAs
Falls
Assault
Alcohol
What is the primary head injury
The injury that occurs on impact/trauma
Includes the injury to the neurons
Irreversible - brain tissue has limited repair capacity
What is the secondary brain injury
Haemorrhage, oedema, infection, hypoxia etc
Occurs as a result of the primary one
Usually leads to a lack of oxygenation of the brain
Potentially treatable
What are the main effects of scalp lesions
Bruising
Can cause extensive bleeding
Route of infection
What are the types of skull fracture
Linear - straight fracture line that may cross sutures
Compound - open fracture with scalp laceration
Depressed - bones displace inwards (often also compound)
Why should base of skull fractures be considered open fractures
Because they usually create an opening into the paranasal sinuses which gives a route for infection
What is the difference between coup and contra-coup injury
Coup injury occurs at the point of impact – brain will impact the skull at the point the head has been struck
Contra-coup occurs at the opposite point oof the skull
What tends to be the worse injury - coup or contra-coup
Contra-coup
Could either be due to movement of CSF which gives it higher impact
OR
Cavitation - bubbles of low pressure damage the tissue
What is diffuse axonal injury
Widespread disruption of axons due to tearing force
Mainly affects central structures
Occurs at the moment of injury
Can lead to a vegetative state, coma and reduced consciousness
What causes diffuse axonal injury
Blunt force trauma to the head
What causes cytotoxic oedema
Intoxication
Severe hypothermia
What causes ionic oedema
Hyponatremia
Excessive water intake - SIADH
What causes vasogenic oedema
Trauma, tumours, inflammation, infection
What is more common, intradural or extradural haemorrhage
Intradural
Includes subdural and subarachnoids
What causes a traumatic extradural haematoma
Occurs when middle meningeal artery is damaged usually after fracture of squamous part of temporal bone
Minimal immediate damage but if untreated can cause midline shift, compression and herniation
What causes a subdural haemorrhage
Disruption of the bridging veins that extend into the subdural space
Occurs after trauma
Common in the elderly
What happens in an acute subdural haematoma
Clear trauma history
Brain swells and the haematoma has a mass effect
Can cause shifts and herniations
What happens in a chronic subdural haematoma
Very subtle presentation
Often present to GP or very late to hospital
older haemorrhage so will have a yellow appearance
Associated with brain atrophy
What is the definition of a traumatic brain injury
A non-degenerative, non-congenital insult to the brain from an external mechanical force, possibly leading to temporary or permanent impairment of cognitive, physical and psychosocial functions
Head injury is the commonest cause of death and disability in people age 1-40 in UK - true or false
TRUE
Who is at high risk of traumatic brain injuries
Young men and the elderly
Those with previous head injuries
Alcohol and drug abuse
Low income
What situations have high risk of traumatic brain injury
Alcohol - cause of almost half Assault Falls RTCs Sports
When do the majority of deaths from traumatic brain injury occur
Within the first hour
After that there is a second peak as the secondary complications start
How do you immediately manage a TBI
ABC - intubate to secure airway and use C-spine control
GCS and pupil check
Secondary survey for other injuries
What might be relevant in the drug history for a TBI
Anticoagulants
What are the 3 sections of the GCS
Eye opening - out of 4
Verbal - out of 5
Motor - most significant and out of 6
Minimum score is 3, max is 15
The lower the GCS the better the outcome - true or false
FALSE!
Lower the GCS the worse the outcome
Who needs a CT scan
GCS<13 on initial assessment in the ED GCS <15 at 2 hours after injury Suspected open or depressed skull fracture Any sign of basal skull fracture Post traumatic seizure Focal Neurological Deficit More than one episode of vomiting Suspicion of NAI Over 65 Coagulopathy
What are the signs of a base of skull fracture
Racoon eyes - bruising around orbit Battle's sign - bruise behind ears Blood or CSF leaking from ears or nose Haemotympanum Bump
How does an extradural haematoma present on CT
Occurs outside the dura and pushes inward - pressure
Gives a bi-convex/lens shape
How does a extradural haematoma present clinically
Usually due to an injury and they have loss of consciousness
Recovery with a lucid interval
They will then have a rapid deterioration - lowering GCS, possible hemiparesis, unilateral fixed and dilated pupil
Will then go into apnoea and death
What is an intracerebral haematoma
Blood clot within the brain itself
What is the goal of treatment after a head injury
Cant undo the primary insult so focus is on preventing the secondary issues
Avoid hypoxia – give oxygen
Mass lesions – can these be removed so that ICP is reduced
To get a good cerebral perfusion pressure you need to keep MAP up and ICP down
What is the monro-kellie principle
Skull is a closed box, and increased pressure means one component of the contents gets pushed out
CSF will get pushed out into spine first
Once this is exhausted, the brain and blood vessels get pressed on
Which type of herniation can be life threatening
Central
Brain gets pushed out of the foramen magnum which compresses the brain stem
Why do you sedate someone with a brain injury
It reduces the metabolic demand on the brain
Why should you intubate someone with a brain injury
You need to avoid hypoxia as this will cause further brain injury
How can you monitor ICP
Can place a wire inside the head to give a pressure reading
It sits in the ventricles to give accurate reading
How can you manage raised ICP medically
Sedation - benzos etc
Maximise venous drainage - head of bed tilt, cervical collars etc
Osmotic diuretics - mannitol
CSF release - can put in drains
What position should you put the head in to reduce ICP
30’ position
Adjust the head of the bed to achieve this
What is a decompressive craniotomy
Surgical procedure to remove part of the skull to reduce pressure
Risky operation – high infection risk
Need to put an artificial plate in – cosmetic procedure
Should you give prophylactic anti-epileptics to those with head injury
Can cause secondary insult but little evidence that prophylaxis helps
Describe the process of excitotoxicity
Occurs after injury
Excitatory amino acids (Glutamate) released
Activates NMDA receptors
Calcium mediated activation of proteases and lipases
Further cell death
What is needed to confirm a brainstem death
No pupil response No Corneal reflex No Gag reflex No Vestibulo-ocular reflex No motor response No respiration No severe metabolic or endocrine disturbance No hypothermia No drugs
2 doctors must carry out all test
Basically a lack of all brain stem function/reflexes
How do you test vestibulo-ocular reflex
Inject ice cold water into ear and look for eye response
Would normally induce nystagmus
How do you confirm lack of respiration
Pre-oxygenate and then turn off the respirator – look for the CO2 to rise to at least 6Kpa
If there is no attempt at spontaneous respiration then they are brain stem dead
What is a subarachnoid haemorrhage
When there is bleeding into the subarachnoid space - into the CSF
Can be fatal
What usually causes a subarachnoid haemorrhage
Usually a berry aneurysm rupturing
Sometimes AVM
Sometimes its spontaneous
Rarely trauma
How does a SAH present
Sudden onset severe headache - explosive/thunder-clap, worst they've ever had Collapse Vomiting Neck pain Photophobia May have a reduce consciousness
What are the differentials for a sudden onset headache
SAH
Migraine - usually people know what this is but could be their first presentation
Benign coital cephalgia - severe sudden headache after exertion (often during sex)
What is the gold standard test for a SAH
CT scan of the brain
May be negative in some though- follow up LP in case
When is it safe to do an LP
Safe in alert patient with no focal neurological deficit and no papilloedema, or after normal CT scan
What should you do if someone with a suspected subarachnoid haemorrhage has a normal CT
Lumbar puncture
Look for bloodstained or xanthochromatic (yellow) CSF
What is the gold standard for looking for brain vessel abnormalities
Cerebral angiography
Travel up via femoral artery
What are the potential complications of a SAH
Can be immediately fatal or lead to brain damage
Can re-bleed - often the cause of death as missed
Delayed ischaemic deficit
Hydrocephalus
Hyponatraemia
Seizures
How can you prevent re bleeding after a SAH
Endovascular techniques - can place coils into the aneurysm so that blood cannot feel
Surgical clipping - place metal clip across aneurysm to occlude it
How can you treat the delayed ischaemia associated with SAH
Nimodipine - CCB
High fluid intake
How can you treat the hydrocephalus associated with SAH
CSF drainage
Can be done LP or EVD (shunt into brain)
How does SAH cause hydrocephalus
Blood can clog the CSF pathways – either block its reabsorption in the sinuses or block its movement through the ventricles
This increased the pressure in the brain
Causes headache or altered consciousness
How do you treat hyponatremia caused by SAH
Supplement the sodium intake
Fludrocortisone
DO NOT fluid restrict as this can lead to cerebral ischaemia which is worse
SAH lowers your seizure threshold - true or false
TRUE
10% 5 year risk
What commonly causes a intracerebral haemorrhage
Hypertension - 50% of cases
Aneurysm or AVM
How does an intracranial haemorrhage present
Headache
Focal neurological deficit - feature dependant on location of bleed
Decreased consciousness level
How do you investigate an intracerebral haemorrhage
CT - urgent if decreased consciousness
Angiography if there is a suspected vascular anomaly
How do you treat and intracerebral haemorrhage
Surgical evacuation of the haematoma
Treatment of underlying anomaly if needed
What areas have a poor prognosis for intracerebral haemorrhage
Large basal ganglia or thalamic clots
Can lead to major focal deficits or deep coma
What causes an intraventricular haemorrhage
Occurs after rupture of a subarachnoid haemorrhage or if there is an intracerebral bleed into a ventricle
How can you treat AVM
Surgery
Endovascular embolization
Stereotactic radiotherapy
Conservative - have to weigh up risk/benefit
How do you open someones airway if they have a head/neck injury/trauma
You should only do a jaw thrust to open the airway in order to keep C-spine still
Head tilt chin lift cause too much movement
What is the main contraindication to using a Guedel airway (oropharygeal)
Conscious patient as it will make them gag
Otherwise pretty safe to use
What is the main contraindication to using a nasopharygeal airway
Base of skull fracture
The tube can pass through the fracture into the brain
When can you use a full anaesthetic airway
Only if patient is unconscious under GA or in cardiac arrest
What is the definition of unconscious
Not awake and aware of/responding to environment
What is the definition of coma
A state of unarousable unconsciousness
GCS of 8 or less is a definition of coma
At which GCS should you consider intubation
8 or less
This suggests a loss of protective airway reflexes
What is the usual cause of a subdural haematoma
Tearing of the bridging veins under the dura
Usually due to trauma
What is the normal cerebral perfusion pressure
around 70-100
Why is raised ICP an issue
No where for it to go
The heart has to overcome this pressure in order to perfuse the brain (nutrients, oxygen etc.) - maintain CPP
What is the Cushing’s reflex
High BP and low HR in context of brain injury
BP rises to try and overcome the raised ICP and perfuse the brain
Heart rate is lowered - reflex bradycardia triggered by baroreceptors in the neck
How do you calculate CPP
CPP = MAP-ICP
