Head Injury and Space Occupying Lesions Flashcards
what is the head trauma death rate?
10 per 100,000
what kind of injury can head trauma be?
missile (open wound)
non-missile
Which form of head trauma leaves the dura intact?
non-missle
What are the features of missile damage?
focal damage
lacerations
haemorrhage in region of brain damage
high/low velocity
What are the features of non-missile damage?
sudden acceleration/deceleration of the head
brain moves in cranial cavity
general causes are RTAs and Assualt falls
primary injury -> evolves to secondary injury
When is injury in non-missile maximal?
at time of injury
- shear injury to axons and/or
- laceration or contusions of brain tissue
Where are surface contusions and lacerations found?
found on lateral surface of the hemispheres and undersurface of temporal and frontal lobes
What kind of injury can surface contusions and lacerations be and which is more serious??
coup or contracoup (diametrically opposite) contracoup more serious
Where may the surface contusions extend?
into the subcortical white matter
What causes contracoup injuries?
the brain moving back and forth in the skull
What are cerebral contusions?
traumatic/mechanical disruptions of small capillary vessels which are a mix of whole blood and native tissue (plasma, RBCs)
have a mottled/speckled density
What are the commonalities of intracranial haematomas?
10% extradural
56% intradural
What is an extradural haematoma?
blood is between the dura and skull and as it expands removes dura from the skull
What are the forms of intradural haematomas and their commonalities?
- 13% subdural - dura and arachnoid
- 3% subarachnoid - trauma from unusual circumstances
- 15% discrete intracerebral/intracerebellar hematomas
- 25% burst lobe - intracranial/intracerebral haematoma in continuity with a related subdural heamatoma - very serious
What increases the likelihood of serious brain injury and why?
age - as you get older the brain starts to atrophy and thus increases space between brain and skull
What is traumatic extradural hematoma?
usually a complication of a fracture in the temporoparietal region that involved the middle meningeal artery - can cause mid-line shift and herniation
minimal associated brain damage
What can traumatic extradural hematoma cause?
midline shift and herniation - life threatening
Where is traumatic extradural hematoma present?
in 10% of fatal cases
What is a subdural hematoma?
haemorrhage in between dura and arachnoid
What is subdural hematoma caused by?
tearing of the venous vessels that transverse the subdural space
What are the types of subdural hematoma?
acute
chronic
gross
How is an acute subdural hematoma classified?
sever head injury with rapid accumulation of blood
acute neurological deterioration
How is chronic subdural hematoma classified?
only in v.young and v.old
minimal trauma
slow accumulations of blood - enlarges over weeks
How is gross subdural hematoma classified?
acute layer of gelatinous blood
chronic - organised layer of dark, liquified clot surrounded by membranes -> compress the brain
When does raised intracranial pressure occur?
when the volume of brain, CSF and blood exceed the normal of 1600ml
Why is the skull a disadvantage at times?
with increased intracranial pressure it does not allow for expansion of brain parenchyma or CSF volume without a raise in pressure
What are signs of raised intracranial pressure?
- papilloedema - pressure on the optic nerve
- nausea and vomiting due to pressure in vomiting centre in pons and medulla
- headache due to distortion of the dura
- neck stiffness due to pressure on dura around cerebellum and brain stem
Where does brain herniation occur?
through the routes of weakest resistance as a result of raised intracranial pressure
What are the potential routes of herniation?
subfalcine
tentorial
tonsilar
transcalvarium
Where does the subfalcine herniation occur?
cingulate gyrus
What happens with the subfalcine herniation?
unilateral or assymetric expansion of the cerebral hemisphere displaces the cingulate gyrus under the falx cerebri
What is associated with a subfalcine herniation?
compression of anterior cerebral artery
weakness and/or sensory loss in leg
ischemic injury to parts of primary and motor cortex
Where is a tentorial herniation?
medial aspect of the temporal lobe - hippocampal uncus and parahippocampal gyrus
What is associated with tentorial herniation?
ispsilateral 3rd cranial nerve affected
pupillary dilation
impairement of occular movements on side of lesion
What is tonsilar herniation?
displacement of cerebellar tonsils through foramen magnum
Why is tonsilar herniation life threatening?
causes brainstem compression - vital respiratory centres in medulla oblongata
What is a trancalvarium herniation?
where the swollen brain will herniate through any defect in the dura or skill
What is associated with a transcalvarium herniation?
reduction in conciousness
dilation of the pupil on same side as mass lesion
bradycardia
chenye-stoke respiration
What is cheyne stoke respiration?
abnormal pattern of breathing with deeper and faster breaths followed by a gradual decrease that includes apnea - build up of CO2 in apnea -> hyperventilation-> apnea -> CO2
What is a herniation usually treated with an why?
osmotic diuretic to reduce swelling
What can be space occupying lesions?
brain tumours - primary or secondary (lungs tend to metastisize)
abscesses
heamatomas
localised brain swelling
What are the potential effects of rotational forces?
rotation as you fall can cause diffuse axonal injury
- initiates at moment of injury
- can cause a coma
- can lead to vegetative state
- non-missile injury
What occurs in rotational injuries?
widespread disruption to the axons due to shear and tensile strains - causing microglial cells throughout white matter weeks later
Diffuse Axonal Injury (DAI) caused by?
raised intracranial pressure progression of inflammatory disease progression of dementia hypoxia trauma - most common
What are the pathological features of axons from DAI at 2-4 hours?
focal axonal accumulation of APP
What are the pathological features of axons from DAI at 12-24hours?
axonal varicosity (swelling at the site)
What are the pathological features of axons from DAI at 24hours -2 months?
axonal swelling
What are the pathological features of axons from DAI at 2wks to 5 months?
glial reaction
What are the pathological features of axons from DAI at 2mnths to years?
degeneration and loss of myelinated fibres
What occurs to Nav channels in DAI?
increased expression and redistribution to demyelinated segments
expression of primitive 1.2 channel
What does adjusted expression of Nav do?
partial restoration of conductance
has increased energy requirement
increased Na influx
What happens to the calcium exhanger?
brings in calcium influx and activates calpains
causes cytoskeletal disruption and disrupted anterograde flow
What is the issue with the calcium exchanger in head trauma?
not enough energy to remove Na -> need to cool area and use medically induced coma to slow electrical activity -> protect from excitotoxicity
What is found in CTE?
Tau rather than Ab
What is found in regards to tau in CTE?
tau proteins accumulate in CSF - correlates with severity
associated with repeated trauma - key regions of brain
NFTs associated with cerebral atrophy
CTE
chronic traumatic encephalopathy
encephalopathy
disease of the brain
