10 - Acute Head Trauma Flashcards
what are the risk factors for acute head trauma?
- male
- young (15-30) and old (65+) due to fraility
- urban areas
- substance misuse inc alcohol
what is the main way to reduce risk of head injury?
primary prevention:
* seat belts
* helmets alcohol prevention/limits
* health and safety
why is it important to ask medication history with head injury pts?
are they on anticoagulants? - increases damage of bleed
what is the primary survey for head injuries?
C - catastrophic haemorrhage
A - patency, managed vs unsupported and C spne
B - other injuries, apnoea, hypoxia
C - other injuries, hypo/hypertension, heart rate
D - GCS, pupils, C-spine, lateralising signs
E - primary survey (entire body)
alongside CABCDE protocol for head injuries, what two things should you measure?
glucose
temp
why is temperature important in pts with acute head trauma?
coagulopathy is altered quickly when hypothermic
what are 3 clinical signs of a base of skull fracture?
- racoon eyes
- battles sign
- haemotympanum
how can you tell the difference between racoon eyes and black eyes?
in racoon eyes, the tarsal plates are usually spared from bruising
when does a battles sign appear?
24 hours after injury
if CSF is leaking from the tympanic membrane, what does this indicate/
skull fracture
what is haemotympanum?
blood build-up behind the tympanic membrane
according to the NICE guidelines, when should a CT be performed within 1 hour?
- GCS less than 13 on initial assessment in ED
- GCS less than 15 at 2 hours after injury
- suspected open or depressed skull fracture
- any sign of basal skull fracture
- post-traumatic seizures
- focal neuro deficit
- more than 1 episode of vomiting
according to NICE guidelines when should a CT be performed within 8 hours of inury?
- pt aged 65 or over
- history of bleeding or clotting disorders
- dangerour mechanism of injury
- more than 30 mins retrograde amnesia of events before head injury
how can primary brain injury be treated?
it cant - it can only be prevented
what is the primary brain injury?
the original insult
what is the secondary brain injury?
the damage caused after injury b:
* hypoxia
* hypotension/hypertension
* raised ICP
what is the most common and detrimental forms of TBI?
diffuse axonal injury
what is the basic pathophysiology of diffuse axonal injury?
resistant inertia that occurs to brain at time of injury, causes shearing of axonal tracts of the white matter
how does diffuse axonal injury appear on CT?
- relatively normal CT imaging even for severe cases
what is the neuroimaging hallmark of diffuse axonal injury?
diffuse white matter tract lesions
what is an extra-dural haematoma?
extra-axial bleed between the dura and skull bone
what is the most common source of injury in extradural haemotomas?
middle meningeal artery
what is the pathophysiology of extradural haemotoma?
- blunt force trauma resulting in linear skull fracture, with no or minimal displacement
- middle meningeal artery is most common source of bleeding
what does CT imaging show for extradural haematomas?
hyperdense biconves lesions, potentially with associated skull fractures
what is a subdural haematoma?
collection of blood that forms in the subdural space (between dura mater and arachnoid mater)
what is the pathophysiology of subdural haematomas?
tearing of the bridging veins that cross from cortex to dural sinuses
what is one of the main risk factors for subdural haematomas?
increasing risk with increasing age
how do subdural haematomas appear on CT?
cresenteric bleed over the brain
what are the clinical features of subdural haematoma?
- LOC/altered conciousness
- headache + confusion
- raised ICP
- focal neurology
what are the clinical features of extradural haematoma?
- initial LOC, followed by lucid period, furthe drop in drowsiness
- headache
- nausea + vomiting
what are the clinical features of a traumatic subarachnoid haemaorrhage?
tSAH
- LOC
- severe headache
- vomiting
- photophobia
- neck stiffness
- seizures
- neurology
what significantly reduces favourable outcomes in secondary brain injury?
hypoxia + hypotension
what does the Monro-Kellie doctrine describe?
the relationship between the contents of the cranium and intracranial pressure
what are the normal values for intracranial pressure?
5-15mmHg
explain the mumro kellie principle?
- the skull is a fixed volume that cannot expand
- normally, 3 components exist in equilibrium to maintain normal ICP - brain tissue, blood, CSF
- new components (like bleed/mass) can disrupt equilibrium
- compensatory mechanisms (drainage of venous volume and CSF can compensate for a while)
- after that, pt begins to decompensate and ICP rises
how is mean arterial pressure calculated?
CO x SVR
what is MAP?
mean arterial pressure - the pressure pushing blood to the brain
what is ICP?
intracranial pressure - the pressure that MAP has to overcome to get into the brain
what is CPP?
cerebral perfusion performance - pressure of blood going through the brain
in healthy individuals, CPP can fluctuate between what?
50-150
in head injury pts, CPP should not fall below what?
70
what is the initial mechanism of oedema?
CYTOTOXIC
* fluid retained in cytoplasm
* loss of NaK ATPase
* glutamate gated Ca channels open
* Ca draws water in
initial mechanism of oedema
what is the delayed mechanism of oedema?
VASOGENIC
* breakdown of BBB
* fluid and protein extravasation into parenchyma
name 3 herniation syndromes?
- subfalcine
- transtentorial
- tonsillar
what is a subfalcine herniation?
midline shift on CT
what is a transtentorial herniation?
pressure on brainstem and oculomotor nerve
what is a tonsillar herniation?
- through the foramen magnum
- effects medulla - cardiorespiratory centre
what are the 4 main points of medical management for head trauma?
- maintain physiology
- improved venous drainage
- reverse coagulopathy
- anti-epileptics if indicated
what levels show that physiology is maintained in head trauma?
- MAP >90 or CPP > 60
- normocapnia
- normothermia
- normoglycaemia
- avoid hypoxia
how do you improve venous drainage in head trauma?
- head up
- no restrictions
what are 3 further medical management steps for managing head trauma?
- sedaation and paralysis
- hyperventilation (CO2 4-4.5)
- osmotherapy (hypertonic sodium chloride, mannitol)
what are 3 surgical management techniques for head trauma?
- remove mass - burr hole
- remove CSF - external ventricular drain
- remove skull - decompressive craniectomy
