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