Flashcards in CNS Trauma Deck (42):
What percent of head-injury deaths occur prior to hospitalization?
66% (thus, primary-prevention measures are crucial)
Trauma is the leading cause of death up to age _________.
What are the four categories of cerebral injury given in this PowerPoint?
- Contact phenomenon (getting hit with something)
- Penetrating head trauma (GSW, stabbing)
- Accelerational (falling, stopping suddenly)
Describe the four types of skull fractures.
Linear: a crack in the skull
Basilar: anything affecting the base of the skull
Growing: an indentation followed by "popping" back out and resorbing
Which kind of cranial fracture is associated with CSF leak?
Basilar – gravity pulls the CSF down, leading to leakages
Diagnosis of basilar skull fractures is done predominantly by ___________.
clinical features – the convoluted base of the skull is difficult to detect fractures on
What symptoms suggest basilar skull fractures?
CSF rhinorrhea or otorrhea
Battle's sign (a late-appearing ecchymosis posterior to the ear)
Facial nerve palsy
Bleeding from external auditory meatus
What kind of hematoma is often associated with skull fractures?
The lucid interval is characteristic of _________ hematomas.
epidural (symptoms appear later, like an EPilogue appears later in a book)
Epidurals occur when the ______________ is ruptured (blood vessel).
middle meningeal (frequently from skull fractures cutting the artery)
What blood vessels tear in subdural hematomas?
The superficial cerebral veins
What kind of injury leads to subdural hematomas?
Rapid translational injuries (e.g., stopping suddenly or being shaken); think of the reason: your brain moves suddenly and stretches the veins that connect the brain to the dura
Describe the shape of the blood (appearing on CTs) for epidural and subdural hematomas.
Epidural = lentiform, because the dura prevents it from spreading into the parenchyma
Subdural = crescent
What is one reason that subdural hematomas typically have a poorer outcome than epidural hematomas?
Subdural hematomas require a more traumatic injury that will often cause brain contusions; the increased intracranial pressure from the bleeding is added to the intracranial pressure from the bruise's inflammation.
Rotational injuries lead to damage that requires _________ to notice.
What histologic finding is characteristic of rotational injury?
Axonal spheroids (retraction balls of Cajal) 24 hours after injury
What parts of the brain are most commonly the sites of axonal spheroids?
The corpus callosum and brainstem
The brain accommodates to ________ increases in pressure.
long-lasting (that is, the brain does not compress to acute changes in pressure)
Intracranial compensation occurs by decreasing what two fluids?
Venous blood and CSF
Once the compensations of the venous blood and CSF are exhausted, __________ occurs.
rapid increase in ICP
What is the most dire sequela of uncal herniation?
The pressure put on the brainstem – the midbrain in particular
Transtentorial herniation often presents with ____________.
contralateral hemiparesis and ipsilateral mydriasis (a "blown pupil," per Dr. Ojemann) due to compression of the corticospinal tract and oculomotor nerve (which carries the parasympathetic input to the pupillary constrictor)
Central herniation can be very serious. What structure herniates in this condition and why is that a big problem?
The thalamus pushes over – into the third ventricle – and pushes down onto the brainstem.
Why does traumatic brain injury lead to increase in cerebral blood flow?
The mechanical damage (such as pressure or acceleration) leads to widespread release of neurotransmitter; the excess activity leads to astrocyte-mediated vasodilation.
Ischemia and trauma both lead to excess release of ___________.
Cerebral perfusion pressure (CPP) is equal to ______________.
MAP - ICP; the difference between blood pressure and pressure within the skull
What mnemonic did Dr. Ojemann give for the priorities of treating a traumatic brain injury?
If you're examining a patient for a Glasgow coma score and you're rating one half of a bilateral response, how do you score?
You score the best half; for instance, if they have hemiplegia then you only give the motor score for their better half.
Notably, __________ reflexes are not included in the GCS score.
What makes tearing of the bridging veins (i.e., the event that leads to a subdural) more likely?
During excitotoxicity, _________ is released by astrocytes (instead of being taken up).
What triggers cytotoxicity?
Excess potassium outside the cells (released due to excitotoxicity)
___________ is a better predictor of mortality than hypoxia in a patient with a severe TBI.
What is normal intracranial pressure?
-3 – 15 mmHg
Describe the three peak ages for incidence of TBI.
0 - 4: child abuse
24 - 35: recreation + MVAs
65 and older: falls
What are DAIs and what type of injury leads to them?
Diffuse Axonal Injuries; rotational forces
What are the four most common types of cerebral herniation?
Performing a lumbar puncture on a patient with increased intracranial pressure can induce ____________.
herniation, because you're removing some of the column of pressure that's resisting the pressure from the cranium
Describe the pathogenesis of vasogenic edema.
TBI induces widespread release of glutamate; glutamate induces depolarization and thence calcium entry into cells; excess calcium within cells activates proteases and damages the cytoskeleton, leading to damage to the blood-brain barrier and leakage of plasma into the brain.
In the context of head injuries, what is PTA?
By definition, what is a concussion?
Alteration in mental status caused by blunt trauma to the head