Craniofacial trauma Flashcards
superior in the detection of acute epidural and subdural hematomas and non-hemorrhagic brain injury
MRI
more sensitive modality in brainstem injury and to subacute to chronic hemorrhage
MRI, especially with FLAIR, GRE and SWI
particularly sensitive in detection of blood products and can identify small areas of hemorrhage undetectable on GRE sequences or even CT
SWI
provides improved detection of both acute and chronic neuronal injury
DWI and DTI
most common manifestation of scalp injury and can be recognized on CT or MR as focal soft tissue swelling of scalp, located beneath the subcutaneous fibrofatty tissue and above the temporalis muscle and calvarium
subgaleal hematoma
isolated linear skull fractures are managed
do not require tx
management of depressed and compound skull fractures
surgical management
fractures of the temporal bone can be classified either according to the following
orientation relative to the long axis of petrous bone or according to their involvement of the otic capsule
if a temporal bone fracture parallels the long axis of the petrous pyramid, it is termed
“longitudinal” fracture
temporal fractures perpendicular to the long axis of the petrous bone are termed
transverse fractures
represents 70 to 90% of temporal bone fractures. it results from blow to the side of the head
longitudinal temporal bone fx
complications in longitudinal temporal bone fx
conductive hearing loss, dislocation or fx of the ossicels and CSF otorhinorrhea, delayed or incomplete facial nerve palsy
results from a blow to the occiput or frontal region
transverse temporal bone fracture
complications of transverse temporal bone fx
sensorineural hearing loss, severe vertigo, nystagmus and perilymphatic fistula, facial palsy in 30 to 50%, injury to carotid artery or jugular vein
fx that run anterolateral to the otic capsule and are usually caused by direct blows to the temporoparietal region
otic capsule- sparing fractures
fx wherein the cochlea and semicircular canals are damaged. these fx are the result of direct impacts to the occipital region
otic capsule- violating fx
complications of otic capsule-violating fx
facial nerve injury, CSF leak, hearing loss, intracranial injuries such as epidural hematoma and SAH
vessel origin of epidural hematomas
arterial, middle meningeal artery
skull fractures are seen in 85 - 95% of what extra-axial hemorrhage
epidural hge
common location of epidural hematomas
temporal or temporoparietal location
venous epidural hematomas are less common, tends to occur at what areas
vertex, posterior fossa, or anterior aspect of the middle cranial fossa
what collection can cross the falx cerebri
epidural
shape of epidural collection
lenticular or biconvex
extra-axial collection that does not cross cranial sutures, where the periosteal layer of the dura is firmly attached. Near the vertex however, the periosteum forms the outer wall of the sagittal sinus and is less tightly adherent to the sagittal suture. therefore, in this region, this extra-axial collection can cross midline
epidural
subdural hemorrhages are typically what vessel of origin
venous, cortical veins, may also result form disruption of penetrating branches of superficial cerebral arteries
subdural hematoma typically extends over a much larger area that epidural hematoma because
the inner dural layer and arachnoid are not as firmly attached as the structures that make up the epidural space
subdural hematomas commonly present after what type of injury
acute deceleration injury from MVA or fall
brain injury freq seen with acute subdural hematomas
cortical contusions and DAI
shape of subdural collection
crescent shaped
common location of subdural hematomas
supratentorial, located along the convexity. freq seen along the falx and tentorium
subdural collections will not cross the falx cerebri and tentorium due to
dural reflections form falx cerebri and tentorium
subdural hematomas can cross sutures or not
can cross sutures
acute hemorrhage may appear isodense or hypodense on ct, in patients with what comorbidities
severe anemia or active extravasation (hyperacute subdural hematoma)
sediment level in extra-axial hematoma called _____ may be seen either from rebleeding or in patients with clotting disorders
hematocrit effect
contrast study may help distinguish chronic subdural hematoma from atrophy by the demonstration of
an enhancing capsule or displaced cortical veins
transition from acute to chronic subdural hematomas called isodense phase occurs usually between how many days to weeks after the acute event
several days and 3 weeks
indirect signs of subdural hemorrhage in isodense phase
effacement of sulci, effacement or distortion of the white matter (“white matter buckling”), abnormal separation of the gray-white matter junction from the inner table of the skull (“thick gray matter mantle”), distortion fo ventricles and midline shift
dependent layering of the acute, denser blood products within the chronic, hypodense collections is often referred to as the
“hematocrit sign”
acute subdural hematomas appearance on MRI
isointense to brain on T1, hypointense on T2
subacute subdural hematoma appearance on MRI
high signal on T1, due to presence of methemoglobin
as hemorrhage ages in chronic subdural hematomas, they appear what on MRI
T2 signal increases and T1 signal gradually decreases as the hge ages
shape of subacute subdural hematomas frequently have a ____ appearance when seen in the coronal plane
lentiform or biconvex appearance, rather than the crescent-shaped appearance that is characteristic on axial CT scans
extra-axial hemorrhage that is common in head injury but is rarely large enough to cause a significant mass effect. it results from the disruption of small subarachnoid vessels or direct extension into the subarachnoid space by a contusion or hematoma
subarachnoid hemorrhage
sensitive MR sequence in detecting hyperacute SAH
FLAIR and SWI
mechanisms of intraventricular hemorrhage
can result from rotationally induced tearing of subependymal veins on the surface of the ventricles, direct extension of a parenchymal hematoma into the ventricular system, intraventricula blood can result from retrograde flow of SAH into the ventricular system thru the fourth ventricular outflow foramina
patients with IVH are at risk for
subsequent hydrocephalus by obstruction either at the level of aqueduct or arachnoid villi
MC type of primary neuronal injuries in patients with severe head trauma
DAI
characterized by widespread disruption of axons that occurs at the time of an acceleration or deceleration injury. direct impact is not necessary to cause this type of injury
DAI
patients with this type of brain injury are most commonly due to high-speed motor vehicle crashes. these lesions have not been seen as a consequence of simple falls
DAI
loss of consciousness is typically seen in what brain injury that immediately occurs after this injury
DAI
DAI presents as
small petechial hges at the gray-white junction of the cerebral hemispheres or corpus callosum
On MR, nonhemorrhagic DAI lesions appear as
small foci of T2 prolongation (increased signal) on FLAIR images or low ADC on DWI within the white matter
hemorrhagic DAI appears as
low signal on GRE or SWI
characteristic locations of DAI in terms of severity
Mild- frontal and temporal white matter, near the gray-white junction, parasagittal regions of frontal lobes and periventricular regions of temporal lobes
More severe- lobar white matter as well as corpus callosum, esp posterior body and splenium
Most severe- dorsolateral aspect of midbrain and upper pons , in addition to lobar white matter and corpus callosum
part of brain that is affected by DAI in 20% of cases
corpus callosum
manner of injury in DAI of corpus callosum
rotational shear forces
corpus callosum is particularly susceptible to DAI because
the falx prevents displacement of the cerebral hemispheres
areas of focal brain injury primarily involving the superficial gray matter. this lesions are much less likely to have loss of consciousness at the time of injury than are the patients with DAI
cortical contusions
common sites for cortical contusions
temporal lobes above the petrous bone or posterior to the greater wing of sphenoid, frontal lobes above the cribriform plate, planum sphenoidale, lesser sphenoid wing, less than 10% involve the cerebellum, margins of depressed skull fractures
cause of markedly decreased signal on GRE or SWI as a sign of prior hemorrhage
hemosiderin deposit
these hematomas tend to have less surrounding edema than cortical contusions because they represent bleeding into areas of relatively normal brain. they are not necessarily associated with cortical contusion but rather represents shear-induced hemorrhage from rupture of small intraparenchymal blood vessels
intracerebral hematoma
most intracerebral hematomas are located in the
frontotemporal white matter
active extravasation of contrast into the hematoma is called ___. it predicts future expansion of hematoma and worsens clinical outcime
spot sign
uncommon manifestation of primary intra-axial injury and is seen as multiple, petechial hemorrhages primarily affecting the basal ganglia and thalamus. these represent microscopic perivascular collections of blood that may result from disruption of multiple small perforating vessels
subcortical gray matter injury
arterial injury commonly accompanies fractures of the
base of the skull
most frequently injured artery, especially at sites of fixation
ICA, entrance to carotid canal at base of petrous bone and at its exit from the cavernous sinus below the anterior clinoid process
MR findings of vascular injury include
presence of an intramural hematoma (best seen on T1 with fat sat), or intimal flap with dissection, absence of normal vascular flow void with occlusion
imaging that are often needed to confirm and delineate dissections and may also show spasm or pseudoaneurysm formation in injuries to the vessel wall
conventional angiograms
communication between the cavernous portion of ICA and surrounding venous plexus. the lesion typically follows a full-thickness arterial injury, resulting in venous engorgement of cavernous sinus and its draining tributaries
carotid cavernous fistula
on CTA or MR, this lesion may manifest as enlarged superior ophthalmic vein, cavernous sinus, and petrosal sinus flow voids
carotid cavernous fistula
may be caused by laceration of middle meningeal artery with resultant meningeal artery to meningeal vein fistula formation
dural fistulas
cortical contusions and intracranial hemorrhages are more severe when
the period of acceleration or deceleration is very short, such as falls
DAI and gliding contusions are associated with what type of injuries
longer acceleration or deceleration injury, such as in MVA
refers to an increase in blood volume
hyperemia
refers to an increase in tissue fluid
edema
cerebral swelling from hyperemia is most commonly seen in what age group due to loss of normal cerebral autoregulation
children and adolescents
diffuse cerebral edema occurs secondary to
tissue hypoxia
herniation in which the cingulate gyrus is displaced across the midline under the falx cerebri. it is the most common of brain herniation
subfalcine herniation
enlargement of the contralateral ventricle in subfalcine herniation is secondary to obstruction of what foramen
foramen of Monro
this herniation are at risk for ACA infarction in the distribution of callosomarginal branch of ACA, where it becomes trapped against the falx
subfalcine herniation
type of herniation in which the medial aspect of the temporal lobe is displaced medially over the free margin of tentorium. causes effacement of ambient cistern and the lateral aspect of suprasellar cistern
uncal herniation
focal impression on the cerebral peduncle is known as
“Kernohan notch”
type of herniation at risk for mass effect on 3rd cranial nerve and compression of contralateral cerebral peduncle causing a recognizable clinical syndrome characterized by a blown pupil with ipsilateral hemiparesis
Uncal herniation
type of herniation that can be either downward or upward across the tentorium
transtentorial herniation
recognized by effacement of the suprasellar and perimesencephalic cisterns
descending transtentorial herniation
type of herniation in which the pineal calcifications which are about the same level as calcified choroid plexus in the trigones of lateral ventricles, is displaced inferiorly
descending transtentorial herniation
type of herniation in which the vermis and portions of cerebellar hemispheres can herniate through the tentorial incisura
ascending transtentorial herniation
type of herniation that can occur in which swelling or mass effects causes the brain to herniate thru a calvarial defect
external herniation
can occur after subarachnoid or intraventricular hemorrhage as a result of either impaired CSF reabsorption at the level of the arachnoid granulations or obstruction at the level of aqueduct or fourth ventricular outflow foramina
hydrocephalus
posttraumatic ischemia or infarction can result from
raised ICP, embolization from a vascular dissection or direct mass effect on cerebral vasculature from brain herniation or an overlying extra-axial collection
ischemia or infarction secondary to globally reduced cerebral perfusion tends to occur in characteristic ____ zones and is not specific for trauma
“watershed zones”
CSF leak requires a ___ and can occur after calvarial or skull base fractures
dural tear
occurs subsequent to fractures in which communication develops between the subarachnoid space and the paranasal sinuses or middle ear cavity
CSF rhinorrrhea
occurs when communication between the subarachnoid space and middle ear occurs in association with disruption of tympanic membrane
CSF otorrhea
highly sensitive for presence of CSF extravasation
radionuclide cisternography
aka “growing fracture” is caused by a traumatic tear in the dura, which allows an outpouching of arachnoid to occur at the site of a suture or skull fracture. this leads to progressive, slow widening of the skull defect or suture, presumably as a result of CSF pulsation
leptomeningeal cyst
consists of tissue loss with surrounding gliosis and is a frequent manifestation of remote head injury. it may be asymptomatic or serve as a potential seizure focus
encephalomalacia
gliosis appears what on both FLAIR and T2
high SI
appearance of encephalomalacia is not specific for posttraumatic injury, but the locations are characteristic:
anteroinferior frontal and temporal lobes
focal volume loss along the white matter tracts associated with cell death is known as
Wallerian degeneration
most common form of primary brainstem injury is, which affecs the dorsolateral aspect of midbrain and upper pons
DAI
particularly vulnerable areas in primary brainstem injury
superior cerebellar peduncles and medial lemnisci
extreme rare form of indirect primary brainstem injury is the ___. this represents a tear in the ventral surface of the brainstem at the junction of the pons and medulla
pontomedullary separation or rent
secondary brainstem lesions that occur as a result of downward herniation or hypoxia or ischemia, usually involve what part of brainstem
ventral or ventrolateral aspect of the brainstem
this is a midline hematoma in the tegmentum of the rostral pons and midbrain seen in association with descending transtentorial herniation. it is believed to result from stretching or tearing of penetrating arteries as the brainstem is caudally displaced
Duret hemorrhage
another type of secondary brainstem injury that typically occurs in the central tegmentum of the pons and midbrain
brainstem infarct
Mild head injury GCS score
13 to 15
Moderate head injury GCS score
9 to 12
Severe head injury GCS score
8 and below
accounts for at least 80% of deaths from head trauma in children younger than 2 years of age
nonaccidental trauma
represent the second most common skeletal injury in child abuse after long bone fracture
skull fractures
most commonly recognized intracranial complications from child abuse
subdural hemorrhages
described as “whiplash shaken injury” by Caffey
subdural hematomas, retinal hemorrhages in children with metaphyseal long bone fractures
subdural hematomas in child abuse often are found in the
posterior interhemispheric fissure
this can mimic chronic subdural hematomas in neurologically intact infants 3 to 6 months old who present with enlarging head circumference. usually regress by age of 2
benign enlargement of the subarachnoid space of infancy
true or false: epidural hematomas are not frequently seen in child abuse
true
most common intra-axial manifestation of head injury related to child abuse is
diffuse brain swelling
four plain film views for evaluation of facial trauma
caldwell view, shallow waters view, crosstable lateral view and submental vertex view
orbital emphysema is most commonly caused by fracture of the
thin medial orbital wall
most common fractures of the facial skeleton
nasal bone fractures
nasal fractures that can be confused with the nasomaxillary suture and nasociliary grooves, which have the same orientation
longitudinal fx
nasal bone fractures that are more common and are easily detected because they are are oriented perpendicular to the normal suture line
transverse fracture
trauma to this nasal area may lead to hematoma formation between the perichondrium and cartilage, which can cause cartilage necrosis by disrupting the vascular supply
septal cartilage
most common isolated maxillary fx. frequently results from blow to the chin that drives the teeth of the mandible into the maxillary dental arch
fracture of the maxillary alveolus
most common isolated sinus fracture involves the
anterolateral wall of maxillary antrum
isolated orbital wall fractures involve what walls
medial wall or orbital floor
what type or orbital fracture is rarely associated with entrapment
orbital floor fx
fragments from an orbital floor fracture buckle upward into the orbit, an injury referred to as a
“blow-in” fracture
appear as biconve high-density collections along the posterior aspect of the globe, bounded by the optic nerve
subretinal hemorrhage
may occur as a result of decelertion strain, causing damage to the delicate meningeal vessels or direct neural disruption of optic nerve
primary optic nerve injury
type of optic nerve injury that may occur as a result of swelling of the optic nerve within the rigid bony canal with subsequent mechanical compression and vascular compromise
secondary optic nerve injury
one of the most common sites of injury in fractures that involbe multiple facial bones
fractures of the zygoma
on plain films, zygomatic arch is best evaluated on what view
submental vertex view
zygoma articulates with
frontal, maxillary, sphenoid and temporal bones
zygomaticomaxillary complex fractures typically involves the
zygomatic arch, zygomaticofrontal suture, infraorbital rim, orbital floor, lateral wall of maxillary sinus, lateral wall of orbit
injury to this nerve is common in zygomaticomaxillary complex fractures, secondary to fracture of the infraorbital rim at the infarorbital foramen
infraorbital nerve injury
all Le Fort fractures involve the ____, which helps anchor the facial bones to the skull
pterygoid plates
type of Le Fort: “floating palate”, horizontal fracture through the maxillary sinuses. etends thru the nasal septum and walls of the maxillary sinuses into the inferior aspect of the pterygoid plates. recognized by fracture of all walls of both maxillary sinuses
Le Fort I
type of Le Fort: “pyramidal” fracture. fracture thru the medial orbital and lateral maxillary walls. begins at the bridge of the nose and extends in a pyramidal fashion thru the nasal septum, frontal process of maxilla, medial wall of orbit, inferior orbital rim, superior, lateral and posterior walls of the maxillary antrum, midportion of pterygoid plates. zygomatic arch and lateral orbital walls are left intact. usually associated with postrior displacement of the facial bones, resulting in a “dish-face” deformity and malocclusion. infraorbital nerve is freq injured
Le Fort II
type of Le Fort: “craniofacial disjunction”, is a horizontally oriented fx thru the orbits. It begins near the nasofrontal suture and extends posteriorly to involve the nasal seputm, medial and lateral orbital walls, zygomatic arch, base of pterygoid plates. also have dish-face deformtiy and malocclusion. infraorbital nerve injury is less common. elongated appearnce of the orbits on Waters and Caldwell views
Le Fort III
describes the constellation of findings seen as a result of a blow to the midface between the eyes. this may include fx of lamina papyracea, inferior, medial and supraorbital rims, frontal or ethmoid sinuses, orbital roofs, nasal bone and frontal process of maxilla, sphenoid bone
nasoethmoidal complex injuries/orbitoethmoid or nasoethmoid-orbital fractures
on plain films, this fracture shows posterior displacement of the nasion in lateral view
nasoethmoidal fractures
nerve that is frequently injured when nasoethmoidal complex fractures injure this structure
cribriform plate
mandibular series includes
PA lateral, Towne and bilateral oblique projections
simple mandibular fx are most common in the ______ and do not communicate externally or with the mouth
ramus and condyle
compound mandibular fractures are those that communicate internally thru
a tooth socket or externally through a laceration
fractures of the body of the mandible are almost always a
compound fx
subcondylar mandibular fx are often recognized on plain films by _____ sign, a well corticated density seen abive the condylar neck on lateral views because of the horizontal axis of the fragment
cortical ring sign
common pattern of mandibular injury
unilateal condylar fx with contralateral fx of the mandibular angle
most common site of isolated mandibular injury
mandibular angle
