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Head and Neck Trauma: An Overview of Radiologic Findings

Overview of the CT and MR findings of various neurologic emergencies

Justin Skweres

on 1 March 2017

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Transcript of Head and Neck Trauma: An Overview of Radiologic Findings

Head and Neck Trauma
An Overview of Radiologic Findings in Cranial and Spinal Trauma
Imaging In Head Trauma
Learning Objectives
To describe the typical radiologic findings in head and neck trauma
To provide an overview of the epidemiology of and the mechanism involved in the various conditions described
To present relevant guidelines and recommendations relating to appropriate imaging and management
CT is the indisputable modality of choice and compliments what may be difficult physical exam due to altered consciousness

Noncontrast CT often the first choice to evaluate for hemorrhage

MR may be helpful in situations where clinical findings exceed expectations - to check for DAI or cerebral contusions
Classifying the Mechanisms of Head Trauma
Type of Injury
Most damage due to change in brain shape +/-deformation of the skull without a change in volume
MECHANISMS - (1) Direct Blow, (2) Acceleration
Superficial injuries are most common and result in CEREBRAL CONTUSIONS - often associated with skull fractures
Coup vs Coutrecoup
Projectile (bullet) vs nonprojectile (knife)
For projectiles - a cavity is created, often with missile and other foreign contents, shockwave damages surrounding tissues
superficial, tangential, penetrating (still in calvarium), perforating (exits calvarium)
Velocity - high vs low velocity
low velocity (non military) projectiles exhibit fragmentation because they are not usually jacketed
Penetrating injuries - infections, CSF leaks, delayed hemorrhage, migration of bullets
Head Trauma
Imaging Modalities
CT - better in the acute setting to detect
treatable conditions before secondary neurologic
damage occurs
MR - longer exams, issues with life support
equipment, inferior bone detail; best in subacute
to chronic traumatic injuries, better predictor
of prognosis
Mechanics of Neuronal Injury
Experiments in primate models have shown all forms of major intra-axial head injuries and subdural hematomas can be produced by purely rotational acceleration (no head impact

Only epidural hematomas and skull fractures require impact!
Calvarial Fractures
Intra-axial injuries
Non-displaced, linear most common
CT imaging of choice - bone algorithm
Treatment required with depressed
or complex fractures
Longitudinal Temporal Bone Fracture (red arrow)
Extra-axial Injuries
Epidural Hematoma
Subdural Hematoma
Subarachnoid hemorrhage
Intraventricular hemorrhage
Diffuse Axonal Injury
Cerebral contusions
Fracture of skullbase (A) with cisternogram (B) showing small encephalocele and CSF leak
Diastasis of the right lambdoid suture
(white circle)
Contrast administered via lumbar puncture
Encephalocele and CSF leak
Underlying injuries
Cortical contusions, or thrombosis/infarction
tearing of dural sinuses, cortical veins, and arteries - classically the middle meningeal
extra-axial hemorrhage
intra-axial injury
Overall, trauma most common cause of SAH; incidence reported to be 33-60%
Acute bleed in sulci bilaterally
Characteristic CT appearance -
hyperattenuating sulci / cisterns
Blood along tentorium - SDH vs SAH?
if extension into the sulci, there
is subarachnoid involvement
FLAIR images show
hyperintense signal
MR imaging shows hyperintensity on FLAIR sequences
Postcontrast FLAIR has even higher sensitivity for acute SAH
Warning: Limited evaluation of posterior fossa due to flow artifacts
Complications of SAH -
Communicating hydrocephalus
Vasospasm and infarction
Right occipital bone fracture at area of impact and resulting countre-coup injury of with hemorrhagic contusions of left frontal lobe with associated extra-axial hemorrhage
Vascular Injuries
Primary Injuries
Primary vs Secondary
Extra-axial vs Intra-axial
Secondary Injuries
Two axial CTs with SAH
T2*GRE image
Other Examples SAH
Subdural vs Epidural
Epidural - above periosteum - does not cross the cranial sutures
Subdural - potential space between dura and arachnoid, freely crosses sutures
convex inward
Overview Spinal Trauma
Stability vs Instability
Arterial laceration along the inner table of the skull
Generally do not cross the tough attachments of dura at cranial sutures
EXCEPTION - arterial EDH can cross the sagittal suture at the vertex, dura less well attached here
90% associated with calvarial fractures - classically middle meningeal
Complications - increased ICP --> herniation
Mixed hyper/hypoattenuation - sign of active bleed
(A) shows small mixed
attenuation bleed of the middle cranial fossa. (B) CT a few
hours later shows marked increase in size.
EDH, right middle cranial fossa
Venous Epidural Hematoma
Slower bleeding from lacerations of the dural venous sinuses. Notice extension of EDH from supra- to infratentorial regions suggesting laceration of the venous sinus as the cause
Due to rupture of the bridging cortical veins
Predisposed - brain atrophy (age, alcoholism), anticoagulated patients, rapid decompression/shunting of hydrocephalus
Often contrecoup
Acute SDH in patient stabbed with knife
Classically crescent shaped, crosses suture lines, tracks along dural reflections
May be delayed, as in this patient s/p fall on Coumadin therapy
Acute Vs. Chronic SDH
Imaging Characteristics
These findings CANNOT be reliably extrapolated to extraaxial blood!
Possibly increased time of evolution due to higher oxygen tension, dependent on hematocrit and field strength
Chronic SDH at CT
SDH is hypodense, but remains hyperdense to CSF
Normal CSF
Same patient's MR...
Axial T2 FLAIR
Note the signal of the fluid DOES NOT suppress and the varying intensities of the areas withing the SDH
Treatment may require decompression if impending herniation
Higher risk in anticoagulated patients, suspect delayed hemorrhage
Acute on Chronic SDH -
Acute blood seen as hyperdensity in hypodense chronic subdural hematoma. Notice the HEMATOCRIT EFFECT!
Hematocrit effect
Axial CT and T2 weighted images showing hematocrit effect in two different patients
Usually associated with other types of intra or extra-axial hemorrhage

Usually seen as blood pooling in the dependent portions of the lateral ventricles
At risk for obstructive hydrocephalus

Check the occipital horns!
Associated with tearing of subependymal veins
Hemorrhage in the occipital horns of the lateral ventricles
Is My Patient Going to Die?
Justin Skweres, MD
Maxillofacial Injury
Injuries to the capillaries and associated edema
Anterior and inferior surfaces of the frontal lobes and occipital and temporal poles
Often contrecoup
More likely to be hemorrhagic than DAI
Subsequent imaging shows enlarging or new hemorrhage
Contusion Progression and Prognosis
Hemorrhagic contusions represent areas of focal ischemia
Larger contusions --> increased chance of enlargement on subsequent imaging
Size of contusion and associated SDH (burst lobe phenomenon) were predictive of hemorrhage progression
The Burst Lobe
Burst lobe phenomenon - related to rupture of a large contusion into the subdural space
This is a poor prognostic sign
Large contusions, associated SDH, low GCS - associated with delayed clinical deterioration
"Spot sign" - sign of active bleeding and was predictive in a study of nontraumatic patients of continuing hemorrhage
Due to differential acceleration of parenchyma of varying density (ie grey white junction)
Can occur without direct blow to the head
Often less hemorrhagic than more superficial cortical contusions
Occurs most often in the grey-white matter junction, next most common deep white matter
DAI Grading Based on Location
Grade 1 - lesions in the grey-white matter junction or deep white matter
Grade 2 - lesions in the corpus callosum, most often the splenium
Grade 3 - lesions in the dorsolateral midbrain and upper pons
Hemorrhagic grade I DAI of the grey-white matter junction seen due to signal loss on T2*GRE
MR is superior to CT to demonstrate extent of DAI
CT is relatively insensitive for DAI when the lesions are non-hemorrhagic
One study found that only 19% of DAI lesions were hemorrhagic - many missed at initial NCCT
MR is very sensitive for DAI lesions, hemorrhagic or non-hemorrhagic, particularly with newer sequences
DAI findings at MR
Blood-sensitive sequences are particularly useful - T2*GRE, susceptibility-weighted imaging
Diffusion weighted imaging and apparent diffusion coefficient mapping
DWI and ADC map showing DAI of the splenium of the corpus callosum (grade II DAI). One small retrospective study showed DWI to be more sensitive than T2/FLAIR or T2*GRE for DAI lesions
Restricted Diffusion
Axial T2*GRE image showing signal loss due to susceptibility effect
T2*GRE (left) and SWI (right) images. Notice the more conspicous lesions on the SWI sequence
Findings at CT
CT less sensitive and only useful for visualizing hemorrhagic lesions
Axial CT images showing hemorrhagic DAI - Grade II lesions involving deep white matter and splenium of corpus callosum
Chronic DAI findings persist as hemosiderin deposits
Chronic DAI seen as T2 hypointensity corpus callosum and upper midbrain
CTA after nail to the head!
Vascular Injury Mechanisms
Subintimal versus Subadventitial Dissection
Subintimal dissection
Results in the narrowing of the true lumen and eventually OCCLUSION resulting in downstream ischemia
T1 hyperintensity representing intramural hematoma
Subadventitial dissection
Results in pseudoaneurysm formation and possibly traumatic arterovenous fistula
Carotid-cavernous fistula
Dissection of right ICA
Resulting from head trauma (or ruptured aneurysm - symptoms include chemosis and pulsating exophthalmos
Subintimal dissection can lead to occlusion, thrombosis and embolization, and downstream ischemia
Delayed Contusions and DAI are always possible...
Always need short term follow up!
Secondary vascular injuries
Can result from damage to adjacent vascular structures during calvarial fracture
Thrombosis of the right internal jugular vein due to right temporal bone fracture
Entrapment of the basilar artery due to fracture of the clivus
Secondary / Delayed Injuries and Long Term Sequelae
Herniation Syndromes
Subfalcine Herniation
Seen as shift of the midline indicating herniation of the cingulate gyrus under the falx to the contralateral side
Many secondary injuries are preventable with apporpriate intervention
Uncal Herniation
Herniation of the medial-most temporal lobe inferiorly through the incisura.
Note compression of left PCA and peduncle, compression of left ambient cistern, and dilated lateral ventricles indicating obstructive hydrocephalus
Cerebral Edema
Blunting of the sulci bilaterally
Decreased attenuation of the cerebrum and loss of grey-white matter differentiation
Sparing of the infratentorial structures (cerebellum) in this case make them appear relatively hyperintense
Note SDH of the tentorium
Axial CT image of infant following strangulation
Tonsilar Herniation
Herniation of the cerebellar tonsils inferiorly with compression of the cervical spine
Spinal injury distribution - 55% cervical, 15% thoracic, 15% lumbar, and 15% lumbosacral (systematic review by Sekhon and Fehlings); HOWEVER - spinal fractures more common in thoracic/lumbar
Risk of spinal cord injury is much higher in the cervical spine than thoracic or lumbar
Cervical spine fractures - mostly in upper and lower ends (C1, C2 and C6, C7) - C2 fractures are more common in elderly
Most thoracolumbar fractures occur in the lower thoracic and upper lumbar spine - and the majority of these do not have spinal cord injury
Indications for Imaging
High NEGATIVE PREDICTIVE VALUE for abscence of a cervical spine fracture (sensitivity 99.6% reported)
If all of the following are ABSENT, imaging is not indicated:
1. No midline cervical tenderness on exam

2. No focal neurologic deficit

3. No alteration in consciousness

4. No intoxication

5. No painful, distracting injuries
Canadian Cervical Spine Group
Low risk of cervical spine fracture when the following criteria are met:
Sensitivity 100% reported and specificity of 42.5% - also a high NPV
1. Normal GCS of 15

3. Presence of low risk factors **
2. Absence of high risk factors *

4. The ability to actively rotate the neck 45 degrees left and right
*High Risk Factors:
age >65 years, high risk mechanism (fall >3m or 5 stairs, high speed MVC, axial loading, bicycle or motorcycle crash, parasthesias in extremities)
**Low Risk Factors
simple MVC, sitting position in ER, ambulatory at any time, no midline tenderness
Both the NEXUS and CCSG studies showed a high NPV for cervical fracture, neither shown to be superior to the other
These guidelines are for adults and cannot be extrapolated to children
Use the "Three Column Theory" of Denis
Line 1 - The soft tissues posterior to the airway
Line 2 - The line connecting anterior aspect of vertebral bodies
Line 3 - The line connecting the posterior aspect of the vertebral bodies
Line 4 - Spinolaminar line
Normal distance of dens to anterior arch is <2.5mm in adults; if more, suspect rupture of transverse ligament
C1-C2 dislocation with rupture of the transverse ligament
Jefferson fracture on radiography (A) and at CT (B). Notice the displaced lateral bodies of C1 on dens in the open-mouth view and the asymmetry of the two sides
"Hangman's fracture" - hyperflexion/distraction injury of C2 (ie. head vs. dashboard). Notice the SPINOLAMINAR LINE is displaced posteriorly at C2
Two or more columns involved = UNSTABLE
Stable vs Unstable
Radiologic Signs of Mechanical Instability
1. Displacement/Translation > 2mm (ligamentous disruption

2. Widening of interpedicular distance, the facet joints, or the interspinous spaces

3. Disruption of the posterior vertebral body line

4. Loss of height of vertebral body > 50%

5. Kyphosis > 20 degrees
Increased basion to dens distance indicating atlanto-occipital dislocation. There is increased lateral distance from lateral masses of C1 to occipital condyles seen on coronal view
Fracture through the anterior arch bilaterally of C1 at junction of arch and lateral masses. Mechanism - axial loading
Classic Jefferson Fracture
Atlanto-Occipital Dislocation
Atypical Jefferson Fracture
(A) Lateral radiograph, no evidence of fracture
(B) Open mouth view and (C) axial CT show unilateral fracture through the anterior arch of C1. NOTE: can be difficult to distinguish from congenital nonunion
Hangman's Fracture
Internal Carotid Artery Injury
Seen best at CTA of the head
At left, there is a traumatic pseudoaneurysm of the left ICA with an associated fracture of the left sphenoid sinus wall
One small series found carotid canal fractures identified at CT had sensitivity/specificity of 60%/67% for ICA injury
Sphenoid sinus air/fluid level had a higher sensitivity (98%), but low specificity for ICA injury
Pseudoaneurysms are prone to rupture and can cause local compression
Spinal Trauma
Cervical Spine Trauma
Plain Radiography
Evaluation of the cervical spine should always begin by inspecting alignment as follows
Think Mechanism!
Found One Lesion, Intensify the Search For Another, Don't Relax!
Results from a noose, or the dashboard (sudden deceleration, hyperextension/distraction injury to the pars interarticularis)
Fracture is through the weakest part of the axis - the articular portions of the pedicles (PARS INTERARTICULARIS)
This results in traumatic spondylolisthesis
Unstable lesions are more likely to progress to neurologic injury, major deformaty, or incapacitating pain
Axial loading
Lateral Flexion
(Atlantoaxial dissociation, flexion teardrop)
(Hangman fxr, Extension teardrop)
(Burst fxr, Jefferson fxr)
(Occipital condyle, transverse process fxr)
70-90% are "longitudinal," or parallel to the long axis of the petrous bone, the remainder are "transverse" or "mixed"
Temporal Bone Fracture
Results from blow to side of head - generally less severe, may have facial palsy
Blow to occiput or frontal region and is generally more severe. May have hearing loss, facial palsy, carotid canal or jugular foramen fxr
Longitudinal vs Transverse Classification
CSF Leak Due to Skullbase FXR
Otic Capsule Classification
Otic Capsule Sparing:
Anterolateral to the otic capsule, less risk of complications
Otic Capsule Violating:
Involvement of the cochlea or semicircular canals - higher risk of CSF leaks, hearing loss, and facial nerve injury

Depressed Fractures
Occipital Condyle Fractures
Three types - Type I is a comminuted fracture of the condyle (uncommon) due to axial loading, Type II is fracture extending into condyle, Type III (most common and most severe) is avulsion of inferomedial fragment into foramen magnum (unstable)
Odontoid Injuries
Type I injuries involve avulsion of the tip, which must be differentiated from os odontoideum - a well corticated ossification center above a rudimentary dens
Type II is a transverse fracture at the base of the dens - this is the MOST COMMON and MOST LIKELY TO GO ON TO NONHEALING
Type III is a fracture that extends into the lateral body of the axis and must be distinguished from isolated lateral body fracture (rare)
Type II fracture of the dens with posterior displacement
T2, T1, and STIR images showing type II fracture with intact posterior longitudinal ligament and no cord damage
C2 Fractures and The Elderly
Type II fracture of the dens in an elderly patient. C2 Fractures are more common in elderly patients due to osteopenia and degenerative changes
Type III axis injury. Plain radiograph demonstrates mild subluxation of C2 on C3 only. CT shows C2 body fracture extending into the dens
Type II
Type III
The Cervicocranium
Subaxial Injury
Gunshot Wounds
Bullet path can be seen as a hemorrhage streak on CT. Bullets that cross the midline or those that fragment have the worst prognosis
Beveled appearance is characteristic of the entry site.
Bone and scalp debris also forced into lesion results in increased risk of infection
Depressed skull fracture
With associated epidural hematoma
Regular Old MR in Acute DAI
Proton density (left) and T2-weighted (right) images of acute DAI are HYPERINTENSE
Within 3-4 hours - short term follow up needed!
Sagittal T1 image showing contusions of the frontal and temporal lobes
Clay Shoveler Fracture
Historically heavy lifting, now often with trauma. This is a STABLE fracture of the spinous process of C6-T1 due to avulsion during hyperflexion
Anterior Subluxation
(A) Lateral radiograph shows anterior subluxation of C4 on C5. (B,C) Flexion/extension images do not show increased subluxation or kyphosis.
Anterior subluxation involves damage to the posterior longitudinal ligament with a normal anterior longitudinal ligament - IMPORTANT to recognize as FAILED LIGAMENTOUS HEALING can lead to INSTABILITY
Bilateral Interfacetal Dislocation
AV Fistula
Flexion Teardrop Fracture
The most severe of flexion injuries - most often in the lower C-spine (C5). Disruption of ALL, IVD, and PLL. Retropulsed fragments lead to anterior cord syndrome. UNSTABLE!
A more severe hyperflexion injury in which the facet joints dislocate - often associated with anterior compression fractures, UNSTABLE
Double Vertebral Body Sign
Predisposed to Ext Injuries:
Ankylosing Spondylitis
Diffuse Idiopathic Skeletal Hyperostosis
Acquired or congenital spinal stenosis
Articular Pillar Fracture
Extension/rotation injury involving the lateral masses and often extending into the transverse process - these are usually STABLE (posterior column only)
Extension Dislocation
Distraction of Ant & Mid Columns
Hyperextension Fracture / Dislocation
Note the calcification of the anterior and posterior longitudinal ligaments and syndesmophytes in this patient with ankylosing spondylitis
AS patients are predisposed to hyperext/fracture - here there is fracture of the calcified ant longitudinal ligament and widening of C5-C6 disk space
Bamboo Spine
Extension Teardrop Fracture
Commonly involves the C2 vertebral body. Usually only involves the anterior column and are thus STABLE IN FLEXION, UNSTABLE IN EXT. Mechanism - avulsion due to hyperextension
Cervical Burst Fractures
While normally seen in the thoracolumbar spine, burst fractures can occur in the C-spine with significant axial loading - UNSTABLE, RETROPULSION!
Anatomy of the Viscerocranium
Buttresses of the Face
The face is divided into 5 anatomic regions:
(1) Nasal
(2) Orbital
(3) Zygomatic
(4) Maxillary
(5) Mandibular
Forces delivered to the face are transmitted through the natural buttresses - thus, typical fracture patterns arise
A Tour of Facial Trauma
Nasal and NOE Fractures
NOE = Naso-orbital-ethmoid complex - includes the nasal bone, the ethmoid bone, and the medial orbital rim and medial canthal tendon
Isolated Nasal Fractures - MOST COMMON
Comminuted bilateral nasal fracture
Right Maxillary fracture
Vomer Fracture
Type III Nasal Fracture
Large central fragment that contains the attachment of the MCT
Comminuted central fragment, but MCT attaches at a piece large enough for stabilization
Severely comminuted NOE fracture that extends beneath MCT insertion - repair required
Bilateral NOEC Fxr
comminuted nasal fracture
Ethmoid sinus fractures and fracture of the lamina papyracea (medial orbital lamina)
Orbital Fractures
NOEC Fxrs are associated with increased Interpupillary distance, flattening of nasal dorsum, and telescoping!
Subacute SDH Can Hide on CT
Isodense to brain in the subacute phase, can be difficult to see. Look for the THICK GREY MATTER MANTLE and DISTORTION OF THE VENTRICLES
Subacute SDH Can't Hide on MR
HYPERINTENSE signal on T1 weighted imaging due to the presence of methemoglobin
Intracerebral Hematoma
Isolated hemorrage in the parenchyma without associated cortical contusion
Shear stress injury resulting in tearing of small parenchymal vessels
Less common
Biconvex Bleed
Midline Shift
Assoc Hemorrhagic Contusions
Epidural Hematoma
Check underneath!
(Methemaglobin again)
Brain Stem Injuries
Primary -
Secondary -
Most common DAI, dorsolateral midbrain
Herniation; classically Duret Hemorrhage from DESCENDING TRANSTENTORIAL herniation
Brainstem DAI at CT (left) and T2W MR (right) typically involves the dorsolateral aspect of the midbrain/upper pons
Central hemorrhage in the pons classically seen with descending transtenorial herniation thought to be due to stretching of penetrating arteries as brainstem is displaced
CSF Leaks
Leptomeningeal Cysts
2 Weeks
6 Weeks
(seen previously)
Classified the same as extracranial arterial injury - subintimal and subadventitial dissection
Subadventitial dissection causes pseudoaneurysm and arteriovenous fistulas
Blow-In Fractures
Result from fracture of the superior orbital rim from direct trauma, or fracture of the frontal bone only from transmitted force. Both result in DOWNWARD displacement and DECREASE in orbital volume
Complex Supraorbital fracture involving the sphenoid bone. Involvement of the APEX of the orbital space by fragments can damage nerves (II, III, IV, V1, VI) and vessels
Fragments involving orbital apex
Fragment in Optic Canal
Blow-Out Fractures
IMPORTANT - No fracture of the infraorbital rim!
Medial Blow-Out Fracture of the right orbit. Involve the ORBITAL FLOOR (MOST COMMON) or MEDIAL wall.
Herniated medial rectus
Inferior Blow-Outs Most Common
Worry about inferior rectus entrapment!
Enophthalmos and Entrapment - repair
If extends into posterior maxillary sinus wall --> difficult repair
Inferior Orbital Blowout
Inferior Orbital Rim Fracture must be noted as it has implications for surgery (Different from Blow-Out)

If you find an isolated orbital rim fracture - look for other injuries
Blood (yellow)
Intraorbital fat (white)
Fragment (short white)
Inferior Rectus
Zygoma Fractures
Direct blow to lateral midface
May involve orbital floor through zygomaticomaxillary connection
Fracture of arch may compress temporalis tendon --> trismus
Arch fracture, compression of temporalis
Indications for operation - important to note:
Significant displacement
Orbital entrapment
Orbital apex involvement (from zygoma-sphenoid connection)
V2 (infraorbital nerve) parasthesia
Zygoma Complex Fracture
Zygo-Frontal suture diastasis; orbital floor fxr
Zygo-maxillary suture fxr
Maxillary Fractures
Common feature - all involve pterygoid plates
Lefort I -
Lefort II -
Lefort III -
Fracture through the alveolar processes of the maxilla; the maxilla and hard palate are distinctly mobile
The pyramidal fracture - from pterygoid plates to inferior and medial orbital walls and terminates in nasal fracture or nasofrontal diastasis; mobile maxilla/nasal region
"Craniofacial disjunction" - pterygoids to zygoma to lateral and medial orbital wall to nasal bone; midface mobile relative to supraorbital regions
Lefort I
Fracture of pterygoids and maxilla just above the alveolar process
Lefort II
Fxr both infraorbital rims and just above the nasofrontal suture
Midface Smash
Severe comminution of the midface that does not conform to any one pattern
Pay attention to soft tissue structures!
Mandibular Fractures
coup-contre coup injuries are common
Right parasymphyseal and left ramus fracture
Another Example CSF Leak
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