Head injuries

Question 1

why aren’t more adults susceptible to damage similar to shaken baby syndrome?

Answer 1

babies have a large head relative to their body, weak cervical musculature, poor control of their head/neck, the cervical cord is different, babies have a higher brain water content, and babies only have a minor degree of myelination

Question 2

what characterizes a subgaleal hematoma?

Answer 2

this hemorrhage is found beneath the galea aponeurotica (directly below the scalp) and is not obvious externally

Question 3

what characterizes terminal fall injuries?

Answer 3

these are often due to loss of consciousness and consist of injuries to the bony prominences of the face - often in *linear distribution. terminal fall injuries may include abrasions, contusions, and lacerations

Question 4

what characterizes cerebral contusions

Answer 4

these appear as a linear streak-like hemorrhage of the cortex and may be due to: coup (stationary head, moving object = wound at impact), contra coup (moving head, stationary object = wound opposite impact), intermediary coup (rotational movement due to battering of head = brain damage due to its own uneven movement), fracture or herniation (w/brain swelling around a falx)

Question 5

what does a series of oval to round contusions on a pt raise suspicion of?

Answer 5

punch

Question 6

what characterizes transtentorial/uncal herniation?

Answer 6

the medial aspect of the temporal lobe becomes compressed against the tentorium, compressing the 3rd nerve = pupillary dilation on the ipsilateral side of the lesion.

Question 7

what is a bite mark to the tongue indicative (but not diagnostic) of?

Answer 7

seizure

Question 8

what characterizes subarachnoid hemorrhage (SAH)?

Answer 8

this hemorrhage occurs between the arachnoid layer and the cerebral cortex. this may occur due to trauma (vertebral artery trauma = basal SAH) or naturally (berry aneurysm, AVM, cocaine, meth). they are not easily wiped off the cortical surface

Question 9

what characterizes diffuse axonal injury?

Answer 9

this due to rapid brain acceleration/deceleration is seen in white matter tracts (corpus callosum, internal capsule, cerebral peduncles) which have a high density of axons. this is most severe in midline and paramidline structures (prone to shearing force). microscopically DAI consists of axonal swelling, disruption of cytoarchitecture/neurofilaments (axonal bulbs), and can be stained for w/beta amyloid precursor protein in as little as 2-3 hours.

Question 10

what can cause periorbital contusions (racoon’s eyes/spectacle hematomas)?

Answer 10

gunshot wound to the head (may generate enough force to fracture the orbital plates)

Question 11

what are the 2 kinds of cerebral edema? what morphology is associated w/it?

Answer 11

1) vasogenic: integrity of the BBB is disrupted, causing *interstitial edema.
2) cytotoxic edema: increase in *intracellular fluid from hypoxic-ischemic insult. morphology: gyri flattened, sulci narrowed

Question 12

what are the categories of soft tissue injury to the head?

Answer 12

subgaleal hematoma
epidural
subdural
subarachnoid hemorrhage

Question 13

What is epidural hematoma?

Answer 13

above dura - typically associated w/a fracture of the temporal bone = middle meningeal artery damage

Question 14

What is subdural hematoma?

Answer 14

below dura - not usually associated w/a fracture, due to tearing of bridging veins - may not require tx

Question 15

Causes of subarachnoid hemorrhage?

Answer 15

ruptured berry aneurysm
cerebral contusion (coup and countercoup injuries)

Question 16

what is a lefort I fracture?

Answer 16

a transverse fracture of the maxilla, above the apices of the teeth and through the nasal septum, maxillary sinuses, and palantine bone of the sphenoid bone

Question 17

what characterizes subdural hematoma?

Answer 17

this is due to tears of bridging veins which link superficial cortical veins to the superior sagittal sinus (though occasionally arteries are involved) and result in compression of gyri and sulci = undulating surface of the cortex (unlike the flattened surface seen in EDH). skull fractures may or may not be present (damage is simply due to movement of the brain inside the skull). SDH’s are good tox specimens. over time chronic SDH may produce a flattened cortex similar to EDH, initially w/an inner arachnoid side membrane + outer dural side membrane - eventually becoming a single fibrous membrane.

Question 18

what is the worst result of cerebral edema?

Answer 18

herniation, which is due to increased ICP

Question 19

are skull fractures common in children?

Answer 19

no - their skulls tend to be more pliable

Question 20

what is the spectrum of diffuse traumatic brain injury?

Answer 20

concussion (functional damage w/o structural damage) and diffuse axonal injury (aka DAI = structural damage)

Question 21

what is shaken baby syndrome?

Answer 21

this is due to rapid acceleration/deceleration of the brain and may not involve distinct impact sites. sub dural hematoma (torn veins), brain swelling, cervical cord injury (RAS etc), retinal/optical nerve injury (retinal hemorrhages are red flags for abuse), possible gripping injury are all associated w/shaken baby syndrome. “respirator brain” is commonly seen in shaken baby syndrome as the brain swelling causes diffuse ischemia, which leads to further swelling, etc = brain starts to fall apart

Question 22

what characterizes tonsillar herniation?

Answer 22

the posterior medial portion of the cerebellum is forced through the foramen magnum

Question 23

what is a gliding contusion?

Answer 23

this is when gliding of the brain under the dura leads to diffuse axonal injury (DAI)

Question 24

what are the different types of skull fracture?

Answer 24

linear (usually due to a simple fall), depressed (fragments into brain), diastatic (sawtooth appearance, younger person - brain swells and pushes out sutures), basilar (battle sign - contusion behind the ear), orbital roof (periorbital ecchymosis - either due to direct or penetrating injury), hinge (usually fatal - fracture going through one side of the skull to the other), and ring (around foramen magnum - spine is pushed up through by upward force from below)

Question 25

what characterizes the morphology of hypoxia/ischemia in the brain?

Answer 25

immediately after insult, the brain may appear normal - but w/in 24-48 hrs, the brain becomes swollen and necrosis may develop = respirator brain?

Question 26

what is a lefort II fracture?

Answer 26

a *pyramidal fracture w/a similar posterior path as a lefort I - however, lefort II fractures also curve anteriorly near the zygomatic-maxillary structure and pass through the inferior orbital rim into the orbital floor and through the medial orbital wall and across the nasal bones and septum.

Question 27

what is a laceration?

Answer 27

a wound due to a blunt object tearing soft tissue (not a cut wound)

Question 28

what characterizes an epidural hematoma (EDH)?

Answer 28

these often involve the lateral temporal and sphenoid bones which the *meningeal arteries are near and present on the surface of the dura. epidural hematomas cause a *linear flattening of the cortex (shelf-like). artifactual EDH may occur in cases like a fire where increased vapor pressure fractures the skull and heated bone marrow moves to the superior surface of the brain. posterior fossa EDH is rare. EDH can be an important tox specimen (b/c it has been sequestered)

Question 29

what is a lefort III fracture?

Answer 29

this is a high transverse fracture involving the maxilla. lefort III fractures pass through the nasofrontal suture, through the medial orbital wall and frontozygomatic suture before passing through the sphenoid bone.

Question 30

what characterizes cingulate gyrus herniation?

Answer 30

unilateral asymmetric expansion of the cerebral hemisphere displaces the cingulate gyrus under the falx cerebri

Question 31

what is a dentoalveolar fracture?

Answer 31

separation of a fragment of the mandible due to anterior or lateral direct force. the fragment often contains a number of fractures

Question 32

what are the categories of facial fracture?

Answer 32

dentoalveolar, lefort I-III and sagittal - all of which require a lot of force (not generally produced in a simple fall).

Question 33

what is a sagittal fracture?

Answer 33

a fracture running in the sagittal plane which passes through the maxilla