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100 Cards in this Set

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TRAUMATIC HEAD INJURY - MURPHY - MONDAY JAN 29
one of what four criteria must be met to constitute head injury?
1) loss of consciousness; 2) amnesia; 3) confirmed brain injury; 4) skull fracture
what % of US population experiences head injury each year, and how many cases are there?
0.2-0.3% (500,000-750,000 cases)
what % of head injuries are fatal?
10%
what % of deaths in the US is head injury responsible for?
1-2%
how much creater is the risk for head trauma, and fatal head trauma, in males compared to females?
2x greater, 4x greater for fatal head trauma
at what age is the highest incidence rate, and what is the incidence of this age group per 100,000?
15-24 years: 550/100,000
what age group has the next highest incidence, and what is it?
over 50: 200/100,000; ages 0-4 and 24-50 years old have incidence of 150 and 160 / 100,000
what are the first, second, and third most common causes of head injury, and what % does each account for?
1) motor vehicle accidents (33-50%); 2) falls (20-30%); 3) violence (7-40%)
in what location are lesions most likely to result in instant death?
brain stem
in what location were they mentioned to be asymptomatic, if a reasonably small size?
frontal lobe
what are the classifications of head injury (6)?
1) penetrating; 2) blunt; 3) open; 4) closed; 5) coup; 6) contrecoup
what does not happen in blunt injury?
direct penetration of cranial vault by object
what is an open head injury?
skull is fractured and dura is penetrated
what is a closed head injury?
skull may or may not be fractured, but dura remains intact
what is a coup head injury?
injury to head structures (skull, meninges, brain) that lie directly beneath the point of impact
what is contrecoup head injury?
injury to head structures that lie opposite to point of impact - occurs when brain is "floating" within skull
what are the types of head injury (3)?
1) skull fracture; 2) parenchymal brain injury; 3) vascular injury
SKULL FRACTURES
what parts of the skull do skull fractures typically involve?
thin parts of the skull, as opposed to thickened, bony ridges
what is the pattern of most skull fractures?
linear - they radiate in opposite directions from the point of impact
do these linear fractures cross suture lines of the skull typically, and why?
no - sutures dissipate kinetic energy that causes the fracture, thus linear fractures tend to isolate themselves within a single skull bone
what is the name for a fracture that does cross suture lines?
diastatic fracture
besides linear and diastatic fractures, what is another type of skull fracture, and what does it involve?
depressed (aka displaced) skull fracture - when a portion of the skull bone is displaced into the cranial cavity
how far into the cranial cavity must it be displaced?
by a distance greater than the thickness of the bone
what may this type of fracture cause (2)?
1) lacerations; 2) contusions
if no damage to brain or meninges occurs, what happens to skull fractures?
heals uneventfully
what complications to skull fractures may there be (3)?
1) damage to brain parenchyma (risk increased with depressed fracture); 2) trauma to intracranial blood vessels; 3) bacterial meningitis
what type of injury to blood vessels is especially likely?
epidural hematoma
what types of parenchymal brain injury are there (3)?
1) contusions; 2) concussions; 3) lacerations
CONCUSSION
what is a concussion?
a clinical syndrome brought about by head trauma
what is it characterized by?
immediate disruption of central nervous system activity - i.e. traumatic paralysis of nervous function
is concussion reversible?
yes, temporary and reversible
when does concussion occur?
when blunt injury causes change in momentum of head - moving head stops suddenly, or stationary head moves suddenly
what are the signs and symptoms of a concussion (4)?
1) loss of consciousness; 2) temporary respiratory arrest; 3) loss of reflexes; 4) loss of muscle tone (person becomes flaccid)
how long can unconsciousness last?
seconds to hours
how long does it usually take for complete recovery to occur?
within 24 hours
what almost always accompanies concussion?
amnesia
what types (2)?
1) retrograde (events before trauma); 2) post-traumatic
how long can amnesia persist?
for a long time, even forever
CONTUSION
what can be torn in contusion, and what cannot?
dura may be torn, but leptomeninges (arachnoid-pia) are intact
is it coup or contrecoup, or can it be both?
can be either or both
where do contusions of the brain occur?
at crests (tops) of gyri of cerebral cortex
what is pattern of hemorrhaging like in contusion, and how is it oriented?
wedge shaped area of hemorrhage, with base of wedge at brain surface
what is the prognosis for brain contusions?
ultimately will heal if given time
what are the clinical complications of brain contusions (4)?
1) headache; 2) dizziness; 3) mental status changes (disorientation); 4) seizures (old contusions are a focus of seizure activity)
LACERATIONS
what types of head wounds cause lacerations (2)?
penetrating head wounds: 1) depressed skull fracture (chunk of bone cuts brain); 2) missile, e.g. bullet
what are clinical symptoms dependent on?
anatomic location
how do lacerations heal?
by scar formation
what does scar serve as?
a focus of seizure activity
TRAUMATIC VASCULAR INJURY
what type of intracranial lesion is formed by an epidural hematoma?
space occupying lesion
in what % of head injuries is there an epidural hematoma?
2%
in what group of people's head injuries is epidural hematoma particularly common?
fetal head injuries (5-15%)
what is epidural hematoma oftentimes accompanied by?
skull fractures
is it normally a coup of contracoup lesion, or both?
normally a coup lesion (contrecoup is unusual)
what is mechanism of epidural hematoma?
blow to head causes tear in blood vessel within dura
what vessels (arteries or veins) are the most common site of trauma for epidural hematoma, and what % result from damage to them?
80-85% result from trauma to the dural arteries (vs. veins)
what is the most common blood vessel involved?
middle meningeal arteries
where are these located?
within the dura on either side of the head (temple regions)
what are the complications of epidural hematomas?
1) compression of adjacent brain (can be dramatic); 2) increased intracranial pressure
what can inreased intracranial pressure lead to?
brain stem herniation through formaen magnum - necrosis of brain stem leads to death
what is the clinical course of an epidural hematoma like, and why?
acute and rapidly progressive, due to high pressure (arterial) bleeding - large hematoma forms quickly - this is a neurosurgical emergency
what is typical clinical picture (3 events)?
loss of consciousness at or shortly after injury, followed by lucid interval which may last for several hours, followed by loss of consciousness again
what is the treatment?
neurosurgery whereby hole is drilled in skull and hematoma is drained
SUBDURAL HEMATOMA
what is the most common source of bleeding?
bridging veins
what type of lesion follows?
space-occupying intracranial lesion
where do bridging veins lie?
they course through subdural space - they are susceptible to tearing
what groups are at increased risk for subdural hematoma (4)?
1) battered infants; 2) alcoholics; 3) boxers; 4) elderly
why are alcoholics more susceptible?
repeated falls with head trauma
why are the elderly susceptible?
brain atrophy leads to stretching of bridgig veins, making them more susceptible to tearing, even after minor head trauma
what is the clinical course like, and why?
because trauma involves veins, subdural bleeding occurs slowly (unlike epidural bleed)
how long after injury do symptoms occur?
days, weeks, or months
what are signs and symptoms due to in subdural hematoma?
mass effect of slowly developing hematoma
what do signs and symptoms include (6)?
1) confusion; 2) loss of consciousness; 3) disorientation; 4) hemiplegia; 5) coma; 6) death
SUBARACHNOID HEMORRHAGE
what is the most common cause of SAH?
head trauma
what is the most common source of bleeding?
veins that lie within subarachnoid space
what does SAH always result in?
bloody CSF
what is the consequence of blood being in contact with the meninges?
causes aseptic, chemical meningitis
what signs does this lead to?
classical signs, such as fever and stiff neck