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
Cerebral parenchymal haemorrhage is __ (more/less) localised.
more
What is the parenchyma?
the bulk of a substance
What is a brain contusion?
Bruise- typically on the surface
Where does a brain contusion most commonly occur? 2 lobes
- Temporal
- Frontal
What are 4 features of a brain contusion?
- Focal surface (on surface) bruise- bleeding, cell death, oedema
- Crests of gyri
- Wedge shaped – broad base at surface
- Often in association with SAH (subarachnoid heaemorrhage) (extra complication)
What are the 2 pathologies in a brain contusions?
- Coup
- Contreceoup
What is a coup (for brain contusion)?
Under the site of impact due to compression forces.
What is a contreceoup (for a brain contusion)?
Opposite side of external impact due to movement of the brain relative to the skull causing a secondary internal impact.
Can you identify a coup and a contreceoup in a specimen?
No, look very similar
What is one of the measurements used clinicially to determine brain injury level?
Glasgow Coma Scale (GCS) scale
When is this test (GCS scale) done?
Lowest GVS score in the 1st 48 hours
How many parts/levels are there in the GCS score? What are the levels?
3 parts
- Eye opening
- Best verbal response
- Best motor response
Why is it important to break down the scores into 3 levels
More information is provided if you break the score down into the three areas, rather than presenting the result as a sum.
What is the score a patient with mild TBI would get?
13-15
What is the score a patient with moderate TBI would get?
9-12
What is the score a patient with severe TBI would get?
<9
The GBS is enough as an assessment for a TBI. True or false.
False
- GCS is useful, and is easy to implement and record.
- However it is better if you combine this scale with other observations to provide a comprehensive overview of the injury.
What is the imaging modality of choice in an acute head trauma?
unenhanced brain CT scan
Why is an unenhanced brain CT scan the imaging modality of choice in an acute head trauma? 6 reasons
- readily available
- fast & accurate for detecting acute intracranial hemorrhage
- on CT, acute haemorrhage is hyperdense to brain
- may display mass effect
- sensitive in distinguishing brain contusions from extra-axial haematomas (subdural and epidural)
- excellent for detecting depressed facial and calvarial fractures
Why is an MRI not preferred compared to a CT scan in acute brain trauma? 2 reasons.
- Takes longer to do an MRI
- Patient may have vital metal medical equipment attached to them that you can’t take into an MRI due to the magnetic field.
If there is significant residual neurological and behavioural deficits in patients with normal CT scans, what is the next step?
T2 MRI is superior in detecting subacute & chronic contusions especially inferior frontal & temporal regions & brainstem (not everyone with a normal CT scan is “clear”)
What is Multivoxel proton MR spectroscopy (H-MRS)?
Quantification of metabolites indicative of different processes
What are 5 features of a mild traumatic brain injury (contusion)?
- Most common type of TBI
- GCS 13 - 15
- Loss of consciousness < 30 min’s (concussion)
- Post-traumatic amnesia < 24 hours
- No macroscopic damage (had CT scan= no affect)
A mild TBI often persists difficulties with ____ and ______.
concentration; memory
With repeated concussions (midl TBI), there _____ (will/still won’t) be long lasting effects/
Will
What are 5 clinical manifestations physically in a mild TBI?
- Fatigue
- nausea
- altered equilibrium
- vision
- hearing
What are 4 clinical manifestations cognitively in a mild TBI?
- Attention
- memory
- processing
- reasoning
What are 4 clinical manifestations of mood and behaviour in a mild TBI?
- Insomnia
- irritability
- depression
- anxiety
Review of 876 patients with a mild TBI (GCS 13-15) and a skull # &/or intracranial haemorrhage on initial CT scan, how many had a ICH (intracranial haemorrhage) and how many had a skull fracture?
- 91.3% had ICH
- 33.3% had skull #
Review of 876 patients with a mild TBI (GCS 13-15) and a skull # &/or intracranial haemorrhage on initial CT scan, what are the 4 types of haemorrhages, and how many people had each one?
- Subdural 41%
- Intra-parenchymal 34.1%
- Epidural 6.7%
- Subarachnoid 2.8%**
In a severe TBI, which haemorrhages are more common?
in moderate and severe TBI, SAH & SDH most common
What percentage of patients with a mild TBI progressed on to RHCT?
13.1% (becomes more severe)
A mild GCS score (GCS 13–15) in patients with an intracranial injury does not preclude progression on repeat head CT and the need for a ______ intervention.
neurosurgical
What are 3 greatest predictors for neurosurgical intervention in patients with mild TBI and an intracranial injury?
- Base deficit >/= 4
- displaced skull fracture
- subdural or epidural haematoma >/= 10mm
What are 3 chronic effects of TBI?
- Dementia / Alzheimer’s disease
- Parkinson’s disease
- Amyotrophic lateral sclerosis
What are 3 effects that Retired athletes with history of >/= 3 concussions report?
3-fold increase in:
- significant memory impairment
- diagnosed depression
- affects life and skills after retirement
What are the 2 types of strokes?
- Ischaemic
- Haemorrhagic
What are the 2 types of ischaemic strokes?
- Thrombotic
- Embolic
What is a thrombotic ischaemic stroke? Do you want to give coagulants?
when a blood clot, called a thrombus, blocks an artery to the brain and stops blood flow. want to give antcoagulations unlike haemorrhagic stroke
Which stroke is more common: ischaemic or haemorrhagic?
Ischaemic is more common
What is an embolic ischaemic stroke?
when a piece of plaque or thrombus travels from its original site and blocks an artery downstream. The material that has moved is called an embolus (more distal site)
What are the 4 factors that cause an haemorrhagic stroke?
- hypertension
- rupture of an aneurysm
- vascular malformation
- complication of anticoagulation medications
What is an intracerebral haemorrhage (ICH)?
bleeding directly into the brain tissue, which often forms a clot within the brain.
What is a subarachnoid haemorrhage (SAH)?
bleeding fills thesubarachnoid space
Place in order from highest to lowest morbidity and mortality. Ischaemic, SAH and ICH. What about prevalence?
SAH > ICH> ischaemic stroke
Ischiaemic stroke > ICH> SAH
Is a spontaenous subarachnoid haemorrhage more or less common than ICH or ischaemic stroke? High or low morbidity and mortality?
Less; high
What are saccular cerebral aneurysms?
acquired lesions that develop at branch points of major arteries of the circle of Willis (eg. internal corotid)
In a spontaneous subarachnoid haemorrhage, there is degeneration of the __________ with secondary thinning/loss of the _____.
internal elastic lamina; tunica media
What is the average size (mm) at rupture in a spontaneous subarachnoid haemorhhage?
6-7mm at rupture
What are 3 characteristics of a spontaneous subarachnoid haemorrhage?
- Early brain injury:
- Transient global ischaemia
- Toxic effects of blood in subarachnoid space
- Delayed cerebral ischaemia
- 1/3 patients in 3-14 days after haemorrhage
- Systemic response:
- Increased sympathetic NS activity
- Angiotensin system activation
- Inflammatory cytokines
How is an early brain injury a characteristic for a spontaneous subarachnoid haemorrhage? 2 features.
- Transient global ischaemia
- Toxic effects of blood in subarachnoid space (does not normally have blood in it)
How is delayed cerebral ischaemia a characteristic for a spontaneous subarachnoid haemorrhage?
1/3 patients in 3–14 days after haemorrhage
How is a systemic response a characteristic for a spontaneous subarachnoid haemorrhage? 3 features
- Increased sympathetic NS activity
- Angiotensin system activation
- Inflammatory cytokines
What are 4 characteristics to diagnose a spontaneous subarachnoid haemorrhage?
- Most severe headache of a person’s life
- Sudden onset** - reaches maximum severity in< 1 min (“thunderclap headache- most important diagnostic indicator)
- Neck pain/ stiffness (limited Cx flexion- irritating structures)
- Non-contrast CT +/- lumbar puncture (to see if blood is present- needle in L3-4 and take a sample of CFS (not always positive and risk of infection))
What are 4 non-modifiable stroke risk factors?
- Age (increasing age)
- Gender (female- subarachnoid)
- Family history
- Previous incident
What are 3 modifiable stroke risk factors?
- High blood pressure
- Stop drink or smoking
- Stop anticoagulants
