Term
| burden of illness of head injury |
|
Definition
high!
80& mild, 10% moderate, 10% severe
enormous cost to society; $billions
prevention is far superior to treatment |
|
|
Term
| epidemiology of head injury |
|
Definition
M>F
young (teens, 20's) more often injurted
elderly mosre often killed
vehicular accidents most common causes (age dependent) |
|
|
Term
| classifications of injury |
|
Definition
primary vs. secondary
focal vs. diffuse
linear vs, angular |
|
|
Term
| overview of primary vs. secondary injury |
|
Definition
Primary:
-occurs at time of trauma
-poorly reversible (prevention is best)
Secondary:
-tissue response to primary insult
-occurs minutes to days following injury
-reversible/preventable |
|
|
Term
| injuriousness of focal vs. diffuse |
|
Definition
| diffuse injuries more injurious |
|
|
Term
layers of the head
(out-->in) |
|
Definition
scalp
skull
dura (dura mater, arachnoid, pia)
brain (gray, white, gray, white, ventricles) |
|
|
Term
list of primary injuries
by layer |
|
Definition
scalp
-subgaleal hematoma
skull
-depressed skull fracture
dura
-epi-/sub-dural hematoma
brain
-focal contusion
ventricles
-intraventricular hemorrhage |
|
|
Term
|
Definition
primary head injury
depressed fractures can tear the dura or lacerate the brain's cortex
basilar skull fractures can damage the vasculature and cranial nerves, and can lead to a CSF leak and meningitis |
|
|
Term
|
Definition
primary head injury
can occur with a skull fracture that lacerates an artery in the richly vascularized dura - often the middle meningeal artery
bleeding expands potential epidural space compressing brain |
|
|
Term
| epidural hematoma presentation |
|
Definition
| blow to temple, brief loss of consciousness lucid interval, appear neurologically well rapid decline in level of consciousness (from mass of growing hematoma) ipsilateral CN III palsy and contralateral hemiparesis |
|
|
Term
epidural hematoma
radiology |
|
Definition
lens-shaped appearance fro dural attachments
can evaluate degree of midline shift or compression of adjacent structures |
|
|
Term
|
Definition
blood between dura and arachnoid from rupture of veins over the surface of the brain
torn bridging veins as a result of shearing force
mass effect from brain injury and hematoma
>50% mortality |
|
|
Term
acute subdural hematoma
radiology |
|
Definition
crescent shaped on CT
often can also see associated brain injury and herniation on CT |
|
|
Term
acute subdural hematoma
presentation |
|
Definition
most present with significantly depressed level of consciousness
may have other findings related to the location of the hematoma (localization) |
|
|
Term
subdural hematoma
intertial injury mechanism |
|
Definition
differential change in velocity, rotation
tearing, shearing forces because brain substance/density is different from that of the skull
tends to be diffuse
more devastation than direct injury |
|
|
Term
| chronic subdural hematoma |
|
Definition
atrophy of the brain places the veins under stretch and injury can occur with much less force in the elderly
more fluid over time from osmotic forces
can present much later that time of injury
much better prognosis that acute |
|
|
Term
chronic subdural hematoma
presentation |
|
Definition
headache, subtle mental status changes
not very ill |
|
|
Term
focal brain contusions
intraparenchymal contusions |
|
Definition
hemorrhage mixed with brain
occur at site of direct blow or a point exactly opposite the point of impact (contra-coup) |
|
|
Term
focal brain contusion
common areas of injury |
|
Definition
often occur in anterior lobes after frontal impact
occur in base of frontal and temporal lobes from brain moving over bony surface of frontal and middle fossa |
|
|
Term
focal brain contusion
presentation |
|
Definition
specific to location in brain
can produce widespread symptoms through mass effect |
|
|
Term
|
Definition
a transient (will get better) and immediate (occur soon after injury) loss of consciousness or normal mentation after head trauma, often associated with a period of amnesia
generally a self-limiting process
duration of confusion/amnesia and +/- loss of consciousness are used to determine a 3-tiered scale of severity |
|
|
Term
|
Definition
observatoin
hydration
supportive care |
|
|
Term
| translation vs. angular motion |
|
Definition
| angular/rotational motion causes much more injury than translational motion and more widespread damage |
|
|
Term
| anatomical considerations for diffuse injury patterns |
|
Definition
based on gray/white matter organization
gray - less dense cell bodies
white - more dense axons
these tissues decelerate at different rates
see injuries at the borderline of gray/white |
|
|
Term
|
Definition
primary injury when axons become sheared off at the boundary between gray and white matter during rapid brain acceleration or deceleration
worse prognosis with shift in midline and effacement of the basal cisterns |
|
|
Term
diffuse axonal injury
radiology |
|
Definition
multiple small, usually <1cm hemorrhages scattered throughout the brain at the junction of the gray and white matter
if bad, may see effacement of basal cisterns and midline shift |
|
|
Term
diffuse axonal injury
presentation |
|
Definition
mild: prolonged mildly concussive state of confusion and memory loss might occur
severe: depressed level of consciousness
focal findings if there are DIA hemorrhages in specific locations such as the internal capsule or brainstem |
|
|
Term
| intracranial compartments |
|
Definition
-venous blood
-arterial blood
-brain
-CSF
the 3 fluid components move in constant flux; pulse of blood into brain causes CSF to be pushed out
compensatory mechanisms of the brain take advantage of this during trauma |
|
|
Term
|
Definition
| given a fixed intracranial volume, any additional material must be accommodated by a decline in the amounts of the others, or a rise in pressure due to the increase in total intracranial material |
|
|
Term
cerebral perfusion pressure
CPP |
|
Definition
CPP = MAP - ICP
an estimate of perfusion pressure to the brain
as ICP increases, less perfusion pressure to get to brain tissue |
|
|
Term
| diagnosis of head injuries |
|
Definition
determining that a head injury has occurred is usually not difficult
assessing the severity is important, more involved
*Glasgow Coma Scale*
-initial CT scan |
|
|
Term
|
Definition
3 component scoring system for assessing head injury severity
-eye-verbal-motor-
earn points for what you CAN do
high score - less injury
low score - more injury |
|
|
Term
|
Definition
ask patient, "What happened?"
1 = no speech
2 = sounds
3 = garbled; non-intelligible speech
4 = disoriented; recognizable speech
5 = oriented |
|
|
Term
|
Definition
1 = eyes closed
2 = eyes open to pain
3 = eyes open to voice (call name repeatedly)
4 = eyes open spontaneously
(pupillary exam is NOT part of GCS score) |
|
|
Term
|
Definition
1 = flaccid, no response
2 = extensor posturing to pain
3 = flexor posturing to pain
4 = withdrawal to pain
5 = localizing to pain; identify/try to prevent noxious stimuli
6 = following commands without any hesitation |
|
|
Term
| severity of head injury based on GCS |
|
Definition
GCS 13 - 15 = mild
GCS 9 - 12 = moderate
GCS 3 - 8 = severe
good prognostic validity |
|
|
Term
|
Definition
indicated in anyone with a GCS less than 15
evaluate for degree of secondary injury (brain edema)
much preferred to skull XR films
currently preferred to MRI in most situations |
|
|
Term
| radiographic markers for cerebral edema, increased ICP |
|
Definition
displacement of spinal fluid --> no black spaces
midline shift
presence of mass effect
loss of the evident pattern of sulci and gyri from CSF displacement
loss of distinction of gray/white matter junction
effacement of basal cisterns |
|
|
Term
|
Definition
result of secondary injury pathways
-hypoxia
-ischemia-acidosis, excitotoxicity
when there are extra things in the brain (edema, increased blood volume, mass lesions) the brain needs to move our of the way |
|
|
Term
| types of herniation syndromes |
|
Definition
|
|
Term
|
Definition
"midline shift"
part of cerebrum is forced from left to right under the falx cerebri (or vice versa) |
|
|
Term
|
Definition
uncus of the temporal lobe shifted medially by a mass or swelling in the ipsilateral hemisphere
compression of CN III - get pupil dilation in ipsilateral eye
may also lose extraocular function - eye turned down and out
compression of cerebral peduncle - contralateral hemiparesis
slight risk of PCA compression/stroke |
|
|
Term
| *clinical syndrome of uncal herniation* |
|
Definition
initial restlessness
somnolence
dilated ipsilateral pupil
contralateral hemiparesis from compression of corticospinal tract |
|
|
Term
|
Definition
intracranial contents forced out the foramen magnum at the base of the skull
tonsils of cerebellum pushed downward, compressing the medulla oblongata
respiratory depression and death |
|
|
Term
|
Definition
constellation of bradycardia, HTN, respiratory irregularity resulting from brainstem compression in herniation event
often a "too late" syndrome |
|
|
Term
|
Definition
ABC - airway, breathing (early intubation), circulation
rapid neuro assessment - GCS
imaging - as soon as ABC's stable; done for ALL patients with GCS < 15 or abnormal neuro exam |
|
|
Term
| conditions warranting emergent surgical therapy |
|
Definition
epi/sb dural hematomas
- >1cm midline shift + declining level of consciousness
intraparencymal hemorrhage
- >25cc volume, mass effect, herniation
debridement of open or penetrating injuries |
|
|
Term
|
Definition
| patient with declining level op consciousness from a surgically treatable lesion has surgical priority over everything except stabilization of ABC's |
|
|
Term
| elevated intracranial pressure |
|
Definition
manifestation of secondary rain injury
-independent predictor of mortatily
detected clinically (low GCS) and with radiographic clues |
|
|
Term
| *indications for monitoring of intracranial pressure* |
|
Definition
GCS 3 - 8
no followable neuro exam
how?
intracranial catheter or transducer into the brain |
|
|
Term
| *intracranial pressure monitoring parameters* |
|
Definition
normal ICP = 5 - 15 mmHg
ICP treatment threshold > 20 mmHg (lower in kids)
measuring ICP allows for calculation of cerebral perfusion pressure |
|
|
Term
| treatment options for intracranial hypertension and cerebral edema |
|
Definition
manage compartments
venous: improve venous drainage
brain: diuretics, barbiturates, hypothermia
arterial: diuretics, adequate oxygenation/ventilation, hyperventilation, barbiturates
CSF: CSF drainage |
|
|
Term
|
Definition
if blood is restricted from exiting the CNS, ICP will increase as the venous compartment size with will larger
loosening cervical collars, elevating head of bed to 30 degrees, and minimizing ventilator pressures all improve venous drainage
very little risk |
|
|
Term
|
Definition
makes more room for brain and edema (and lowering ICP) by reducing size of CSF space
drain from same catheter used to measure ICP
risk of infection and hemorrhage |
|
|
Term
|
Definition
decrease excessive brain metabolism from agitation and pain (metabolism can be toxic, obligates for blood volume to supply the tissue with nutrients)
reduce fighting against the ventilator, reducing venous congestion
limit ability to perform neuro exam; potential for hypotension |
|
|
Term
| osmotic agents and diuretics |
|
Definition
removal of excessive brain water by establishing a favorable osmotic gradient for diffusion of fluid back into blood stream
mannitol - doesn't cross BBB (as long as it's intact!), draws out water, reduce overall brain volume
reduce viscosity of blood = delivery of more blood though a smaller blood vessel |
|
|
Term
| potential adverse effects from different hyperosmolar agents |
|
Definition
mannitol: dehydration
mannitol/hypertonic saline:
-nephrotoxicity from hyperosmolar state
-transit of osmoles to injured brain-->rebound intracranial HTN
-wean slowly |
|
|
Term
|
Definition
nigh metabolic state--> increased CO2 production and acidosis; natural response is vasodilation
increasing respiratory rate decreases intracranial blood volume by vasoconstriction
avoiding elevated CO2 levels (and reduced O2 levels) avoids unnecessary vasodilation and resulting ICP increase
*therapy targets: CO2-35mmHg, O2-100mmHg*
risk of ischemia if go too far |
|
|
Term
|
Definition
high dose barbiturates
hypothermia
surgical decompression
(are they really helpful?) |
|
|
Term
|
Definition
high doses reduce cerebral metabolism
risk of hypotension |
|
|
Term
|
Definition
reduce metabolism
risk of infection and electrolyte risks |
|
|
Term
|
Definition
enlarge the space available for swelling by removing a portion of the top of the skull
possible risk of injury to brain from stretch |
|
|
Term
| stepwise approach to ICP management |
|
Definition
employ less risky strategies first and escalate as needed
apply methods directed at each of the compartments before applying multiple methods to the same compartment
relative order: physiology (ABC), drain CSF, sedation/paralysis, osmotic agents, hyperventilation, barbiturates, surgical decompression, hypothermia |
|
|
