CNS Injury I Flashcards
Translational acceleration from high velocity–> rupture of the bridging veins that connect the cortical brain surface to the sagittal sinus–> hemorrhage into the subdural space–> _______ and _______.
elevated intracranial pressure, distant secondary cerebral injury
What causes “retraction balls?”
shearing of axons
This is bradycardia and HTN in the setting of high ICP.
Cushing’s reflex
What do free radical mediators do?
break down of the BBB–> interstitial (vasogenic) edema–> brain swelling –> increased ICP —> further hypoxia –> dysautoregulation –> herniation
Epidural hematomas typically result from ______.
intracranial, extradural arterial bleeding
What is Cushing’s reflex?
bradycardia and HTN in the setting of high ICP
What is a cerebral contusion?
contusions on the brain caused by an impact or high velocity translational injury
What is a subdural hematoma?
hemorrhage into the subdural space because of rupture of bridging veins that connect the cortical surface of the brain to the sagittal sinus
The principal mechanisms involved in head injuries are either _____ or _____.
- contact
- acceleration/deceleration
This injury occurs at the moment of impact and is largely irreversible.
primary injury
What is a Kernohan’s notch?
when a transtentoral (uncal) herniation compresses the opposite cerebral peduncle against the tentorial edge, causing hemiparesis that is ipsilateral to the mass lesion
This causes break down of the BBB–> interstitial (vasogenic) edema–> brain swelling –> increased ICP —> further hypoxia –> dysautoregulation –> herniation
free radical mediators
What causes subdural hematomas?
translational acceleration from high velocity
What are some consequences of a cerebral contusion?
hemorrhage into areas of damaged brain –> mass effect –> herniation with 2a brain injury
____ in its mild form is thought to underlie the phenomenon of concussion.
Diffuse axonal injury (DAI)
What is the tx for an epidural hematoma?
surgical removal
The highest incidence of head injury occurs in what social class, age, and gender?
- economically disadvantaged
- age 24-35
- males
This is death due to 2nd concussion while still suffering from the 1st one.
second impact syndrome
How is elevated ICP treated?
endotracheal intubation controlled ventilation to a pCO2 of 35mmHg elevation of the head IV osmotic diuretics (mannitol) ventricular catheters drug induced coma w/ barbs
A transtentorial (uncal) herniation compresses the _____ and its ______, usually producing an ipsilateral 3rd nerve palsy and contralateral hemiparesis or hemiplegia.
midbrain; ipsilateral cerebral peduncle
Contact phenomena result from _____.
an object striking the head
This is neuron damage and death by overreaction of receptors for glutamate (NMDA and AMPA).
excitotoxicity
What is the end result of elevated ICP?
reduction and cessation of cerebral blood flow
A ____ compresses the midbrain and its ipsilateral cerebral peduncle, usually producing an ipsilateral 3rd nerve palsy and contralateral hemiparesis or hemiplegia.
transtentorial (uncal) herniation
In _____, the cingulate gyrus is pushed away from the expanding mass and herniates beneath the falx cerebri
subfalcine herniations
This is when the cerebellar tonsils are herniated downward into the foramen magnum (coning) due to mass lesion in the posterior fossa.
tonsillar herniation
These are traumatic separations of the skull at suture lines.
diastatic fractures
What other lesion is a subdural hematoma often associated with?
underlying cerebral contusions
What is a secondary injury?
injury from inadequate resuscitation
This is astrocyte swelling due to K+ influx.
cytotoxic edema
What is the Glascow-Coma Score (GCS)?
an assessment of the head injured pt that correlates w/ the likelihood that the pt has an intracranial mass lesion and the outcome
What is a Duret hemorrhage?
hemorrhage in the brainstem characteristic of uncal herniation –> disruption of ascending RAS
In _____, the uncus herniates across the tentorial edge and downward into the posterior fossa.
transtentorial (uncal) herniation
What is the mortality rate for cerebral contusions?
less than 20%
Name 5 types of skull fractures.
- linear
- depressed
- basilar
- diastatic
- growing
What is the tx for a subdural hematoma?
- surgical removal of the blood clot
- control of intracranial pressure
- restoration of cerebral blood flow
In conditions of extremely elevated extracellular K+, ______.
the glutamate transporter reverses
What is excitotoxicity?
neuron damage and death by overreaction of receptors for glutamate (NMDA and AMPA)
Name the 3 largest causes of brain injury.
- Motor vehicles
- recreation
- violence
What are the steps in the concussion grading scale?
- grade 1 = confusion w/o amnesia or LOC
- grade 2 = confusion and amnesia
- grade 3 = LOC
_____ injuries result from rapid head movement that can create shear, tensile, and compressive strains.
Acceleration/deceleration
What does translational acceleration from high velocity cause?
subdural hematomas
______ typically result from intracranial, extradural arterial bleeding.
Epidural hematomas
What does the Monroe-Kelly doctrine state?
the volume of the CSF + volume of blood in the cerebral systems + the volume of brain + volume of any mass lesion MUST = the volume of the intracranial compartment (constant)
This is a fracture in an infant resulting from dural tears and herniation of the arachnoid into the fracture site–> CSF pulsations –> bone loss.
a growing fracture
What are the common symptoms of brain herniation syndromes?
- progressive lethargy
- poor responsiveness (obtundation)
- headache
- nausea
- vomiting
What causes second impact syndrome?
loss of autoregulation of CNS vasculature–> cerebral vessels lose tone–> congested with blood –> increased ICP –> widespread ischemia and vasogenic edema
This is a hemorrhage in the brainstem characteristic of uncal herniation –> disruption of ascending RAS,
a Duret hemorrhage
What is the tx for a cerebral contusion?
- med mgmt. to prevent brain swelling
- possible surgical evac
DX?
- headache
- dizziness
- poor attention
- inability to concentrate
- memory problems
- fatigue
- irritability
- depressed mood
- intolerance of bright light or loud noise
- sleep disturbance
concussion
A transtentorial (uncal) herniation compresses the midbrain and its ipsilateral cerebral peduncle, usually producing ______ and ______.
an ipsilateral 3rd nerve palsy; contralateral hemiparesis or hemiplegia
Name 2 characteristic locations of cerebral contusions.
- anterior cranial fossa (frontal lobe)
- greater wing of the sphenoid (temporal lobe)
What is a basilar skull fracture?
high velocity blunt injury causes cribiform plate or petrous bone fractures, resulting in CSF leaks
This results from high velocity rotational acceleration/deceleration.
diffuse axonal injury (DAI)
In _____, the pt is always unconscious at time of injury.
Diffuse axonal injury (DAI)
This is a high velocity blunt injury that causes cribiform plate or petrous bone fractures, resulting in CSF leaks and possible meningitis.
a basilar skull fracture
Acceleration/deceleration injuries result from rapid head movement that can create _______.
shear, tensile, and compressive strains
What causes an epidural hematoma?
skull fractures in the distribution of the middle meningeal artery
Acceleration/deceleration injuries result from ______ that can create shear, tensile, and compressive strains.
rapid head movement
What is a depressed skull fracture?
comminuted bone fragments that may be driven into the brain
What is a diastatic fracture?
traumatic separations of the skull at suture lines
This is downward central pressure that causes bilateral uncal herniation.
central herniation
This is when a transtentoral (uncal) herniation compresses the opposite cerebral peduncle against the tentorial edge, causing hemiparesis that is ipsilateral to the mass lesion.
a Kernohan’s notch
This is hemorrhage into the subdural space because of rupture of bridging veins that connect the cortical surface of the brain to the sagittal sinus.
a subdural hematoma
What is a growing fracture?
fracture in an infant resulting from dural tears and herniation of the arachnoid into the fracture site–> CSF pulsations –> bone loss
What is the mortality rate for an epidural hematoma?
less than 20% (if evacuation wi 1 hour)
What is the classic presentation of an epidural hematoma?
- post impact injury
- lucid interval prior to progressive obtundation and coma
In diffuse axonal injury (DAI), MRI shows _____ in large white matter tracts and near the gray-white junction bc of its density difference.
punctuate hemorrhages
What causes a diffuse axonal injury (DAI)?
high velocity rotational acceleration/deceleration
DX?
- mild traumatic brain injury
- alteration of mental status caused by biomechanical forces
- may or may not have lost consciousness
- confusion and amnesia
concussion
In diffuse axonal injury (DAI), MRI shows punctuate hemorrhages in ______ and near the gray-white junction bc of its density difference.
large white matter tracts
Why is second impact syndrome fatal?
once the course begins it’s nearly impossible to stop
What is a linear skull fracture?
high impact injury causing fracture of the calvarium
_____ phenomena result from an object striking the head.
Contact
How does vasogenic edema occur?
excitotoxicity causes BBB compromise –> increased permeability –> brain swelling
What physiological process does progressive lethargy and poor responsiveness (obtundation) indicate?
an acute rise in ICP
What is tonsillar herniation?
the cerebellar tonsils are herniated downward into the foramen magnum (coning) due to mass lesion in the posterior fossa
In ____, the anterior cerebral artery is often kinked and a stroke frequently occurs.
subfalcine herniations
In subfalcine herniations, the ______ is pushed away from the expanding mass and herniates beneath the _____.
cingulate gyrus; falx cerebri
What happens with widespread simultaneous neuronal depolarization?
an immediate spike in extracellular K+
How does secondary brain injury occur?
- hypoxia
- altered blood flow
- release of free radical mediators
What do skull fractures in the distribution of the middle meningeal artery cause?
an epidural hematoma
What is second impact syndrome?
death due to 2nd concussion while still suffering from the 1st one
Name 4 distinct herniation syndromes.
- subfalcine herniation
- central herniation
- uncal herniation
- tonsillar herniation
What can arise from a basilar skull fracture?
meningitis bc of the CSF leaks
What can precipitate a herniation syndrome and why?
a lumbar puncture in the setting of an intracranial mass lesion due to the differential pressure this creates btw the cranial and subarachnoid space
In _____, MRI shows punctuate hemorrhages in large white matter tracts and near the gray-white junction bc of its density difference.
Diffuse axonal injury (DAI)
What is central herniation?
downward central pressure that causes bilateral uncal herniation
What causes cytotoxic edema?
astrocyte swelling due to K+ influx
What is the mortality rate from a subdural hematoma?
40-60%
At what anatomical locations can brain herniations occur?
- across the falx
- across the tentorium
- the foramen magnum
This is when excitotoxicity causes BBB compromise –> increased permeability –> brain swelling.
vasogenic edema
What are the most common s/s of concussion?
- headache
- dizziness
- poor attention
- inability to concentrate
- memory problems
- fatigue
- irritability
- depressed mood
- intolerance of bright light or loud noise
- sleep disturbance
Pathologically high levels of glutamate can cause excitotoxicity by _____.
allowing high levels of Ca++ into the cell
This fracture is diagnosed when comminuted bone fragments are seen that may be driven into the brain.
a depressed skull fracture
What is a primary brain injury?
one that occurs at the moment of impact and is largely irrversible
Anyone with a witnessed LOC needs ____.
a CT scan
This states that the volume of the CSF + volume of blood in the cerebral systems + the volume of brain + volume of any mass lesion MUST = the volume of the intracranial compartment (constant).
the Monroe-Kelly doctrine
This is injury from inadequate resuscitation.
secondary injury
In transtentorial (uncal) herniation, the _____ herniates across the tentorial edge and downward into the _____.
uncus; posterior fossa
What is a concussion?
- mild traumatic brain injury
- alteration of mental status caused by biomechanical forces
- may or may not have lost consciousness
- confusion and amnesia
Name 5 causes of brain herniation syndromes.
- trauma
- ischemia
- neoplasm
- infection
- hydrocephalus
This is a high impact injury causing fracture of the calvarium.
a linear skull fracture
What does tonsillar herniation result in?
medulla compression –> abnormal cardiac and respiratory responses