Neuroanatomy L3: Acquired brain injury Flashcards
What is an acquired brain injury (ABI)?
all types of brain injury that occured after (or during) birth
What are 7 causes of a brain injury?
- traumatic brain injury (TBI)
- stroke
- brain tumour
- poisoning
- infection and disease
- near drowning or other anoxic episodes
- alcohol and drug abuse
Based on traumatic brain injuries, > 2/3 due to ___________ (mechaism of injury).
motor vehicle accidents
Based on traumatic brain injuries, > 2/3 involve ______ (old/young) people, aged ______.
young people; aged 16 - 24 years
Based on traumatic brain injuries, 2/3 of those injured will be ______ (males/females).
males
What is a traumatic brain injury?
“a traumatically induced structural injury and/or physiologic disruption of brain function as a result of an external force”
What are 3 examples of external forces?
- Contact forces
- between the brain and the skull or dural partitions.
- Movement forces
- rapid acceleration/deceleration forces (especially in a rotational direction).
- Blast forces
- the wind from an explosion causing movement of the brain tissue within the skull (has more of an effect than the sound waves from an explosion).
What are 4 clinical signs of a TBI?
- Any period of loss or a decreased level of consciousness
- Any loss of memory for events immediately before or after the injury
- Any alteration in mental state at the time of injury (confusion, slowed thinking etc also includes frustration associated with difficulty trying to think of things.)
- Neurologic deficits (weakness, balance, visual, speech, general sensory)
What are the 5 TBI classification schemes?
- Physical mechanism
- Primary or secondary
- Focal or diffuse
- Pathoanatomy
- Symptoms/severity
What is physical mechanisms in TBI classification schemes?
Blunt trauma, rapid deceleration or blast.
What is primary or secondary in TBI classification schemes?
- Primary = intial symptoms
- secondary = ongoing.
What is focal or diffuse in TBI classification schemes?
Focal = confined. Diffuse/multifocal = widespread.
What is pathoanatomy in TBI classification schemes?
What happened
What is symptoms/severity mechanisms in TBI classification schemes?
GCS = severity
Give idea of diagnosis
What are the 2 pathologic features of traumatic brain injury?
- Primary TBI
- Secondary TBI
What are 4 features of a primary TBI (Focal, multifocal or diffuse)?
occur at the time of the event
- Axonal injury (Diffuse axonal injury (DAI) causes the most problems)
- Vascular injury
- Subarachnoid haemorrhage
- Subdural haemorrhage
- Epidural haemorrhage
- Intracerebral/Parenchymal haemorrhage
- Contusion
- Laceration
What are 5 features of a secondary TBI (Focal, multifocal or diffuse)?
Could be classed as mild/moderate initially, but secondary injury could due to ongoing effects.
- Ischaemic – hypoxic damage
- Brain swelling – congestion (due to molecules, chemicals) /oedema (Increase in fluid in the neural tissue - this increases pressure)
- Raised intracranial pressure
- Neuroinflammation
- Infection
What are 2 factors that makes axons vulnerable?
- Viscoelasticity: rapid deformation “brittle response
- High degree of alignment in tracts
- High axonal alignment is present in the brainstem, internal capsule and corpus callosum (ie. highly homogenous).
- More random alignment is present in the corona radiata (ie. hetrogenous). The response of white matter to injury is based on the alignment of the axons relative to the forces. Viscoelasticity: rapid deformation–> brittle response
- High degree of alignment in tracts
The more peripheral cortex moves at a differential rate (due to the greater moment arm).
Shearing occurs at different regions of the brain.
Tensile forces through the right internal capsule, and compression in the left internal capsule.
What is restricted head movement after impact? What is the effect?
rotational acceleration
tissue deformation
In diffuse axonal injury (DAI), what are 5 features?
- Damage axonal cytoskeleton
- Loss of elasticity (Ability to return to original shape) –> axonal undulation & misalignment (Strained but not broken) -
- Mechanical damage to sodium channels (This occurs as the membrane stretches)
- massive sodium influx
- axonal swelling
- trigger Calcium influx (This activates enzymes to break down proteins of the neuron (ie. proteolysis).
- Calcium activates proteolysis (breaks down protein) further damaging cytoskeleton
- massive sodium influx
- Impaired axonal transport mechanisms (from cell body)
- Accumulation of proteins in axonal swellings
- Secondary axotomy (break down of axons)
What does this imaging show?
- Shouldn’t be able to see the lines or bulbs.
- Lines are swelling of the axon.
- Bulbs are swelling due to accumulation of axon transport materials that have been blocked due to a lesion in the axon.
What are haemorrhages & haematomas?
Result from tearing of blood vessels at the time of injury
What is the middle meningeal artery?
Supplies the dura - if this ruptures and bleeds it can strip the dura off the skull and cause a pathological space (epidural space). Arteries are high pressure, veins are low pressure.
What are bridging veins?
Bridging veins - connection from cerebral veins to the venous sinus. If they bleed, they can split the arachnoid from the meningeal dura (subdural space).
What is this?
What is an epidural haemorrhage? 4 characteristics.
- This is an arterial injury, usually the middle meningeal artery
- It is associated with temporal bone or other skull fractures
- It has a biconvex, lenticular shape; blood is contained by dural sutures
- This is a surgical emergency
For an epidural haemorrhage, especially associated with impact around the pterion. The high blood pressure in the arteries can strip _____ off the skull if the arteries are compromised. It takes awhile for this to develop. The dura is more firmly ____ at the sutures, and will not separate form the skull. Thus the blood ____ (will/won’t) pass the sutures and is contained to some extent.
dura; adhered; won’t
What is a good assessment for a epidural haemorrhage?
CT scan left epidural haematoma
There will be a ___ prognosis for epidural haemorrhage if treated. What does treatment involve?
Good
Treatment involves drilling to release the pressure, and cauterising the artery.
What are 4 features of a subdural haemorrhage?
- This is a venous injury to bridging cortical veins (between dura and arachnoid)
- Skull fracture may not be present
- It is usually crescentic in shape and not contained by sutures; it does not cross falx or tentorium
- This is found in trauma patients (eg. motor vehicles), older patients (tissue is not as strong), and child abuse victims (eg. shaken baby syndrome)
For a subdural haemorrhage, low pressure vessel results in a ___ (slow/fast) bleed, and takes ____ (more/less) time for the low pressure vein to create enough force to separate the dura and ______layers. Injury can occur when the veins move at a different rate to the skull, resulting in ______ forces. Also common in juveniles - called shaken baby syndrome. Brain _____ is present in the elderly, which ______ (increases/decreases) tension on the bridging veins, causing _____ (increased/decreases) susceptibility to failure from shear forces YES!.
slow; more; arachnoid; shear; shrinkage; increases; increases
A subdural haemorrhage is due to _____ trauma. It ___ (is/isn’t) confined like the epidural haemorrhage.
deceleration; isn’t
What are the 3 features of subarachnoid haemorrhage?
- Blood is in subarachnoid spaces; hyperdensity is in CDF spaces
- Aneurysm rupture or post-traumatic superficial cortical contusion are the cause
- Vasospasm several days afterward may lead to secondary infarction (severe-high mortality)
For subarachnoid haemorrhage, blood is free to flow through the whole ______ space - including into the _____fissure. More common in ____ and _____ traumatic brain injury than in the mild injuries. Causes large _____ pain - common form of stroke - also related to ____ (bruises) of the brain.
subarachnoid; longitudinal; moderate; severe; headache; contusions
With a subarachnoid haemorrhage, what does the blood do?
Mingles with the CFS
What is a cerebral parenchymal haemorrhage?
Haemorrhage of small arterioles & capillaries in brain parenchyma