Imaging Of Facial Trauma Part 3 (2) 2
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Transcript of Imaging Of Facial Trauma Part 3 (2) 2
Imaging of Facial Trauma Part 3: Pathology
(Zygomatic, Maxillary and Mandibular Fractures) Rathachai Kaewlai, MD
www.RadiologyInThai.com
Created: January 2007
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Outline
Facial and mandibular fractures Nasal fractures Naso-orbital-ethmoidal fractures Frontal sinus fractures Orbital fractures Zygomatic fractures Maxillary fractures Mandibular fractures
Imaging approach
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Zygomatic Fractures
Two types of zygomatic fractures Zygomatic complex fracture
Isolated zygomatic arch fracture
Relevant anatomy
Malar eminence = surface anatomy of the body of zygoma
Zygomatic fractures can cause limitation of mandibular motion, especially when fractures are depressed Masseter muscle arises from zygomatic arch
Coronoid process is located underneath the zygomatic arch
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Zygomatic Fractures
Zygomatic complex fractures AKA ZMC fracture, trimalar fracture, malar eminence fracture Tripod fracture is a misnomer (zygoma actually has 2 attachments
to cranium and 2 to maxilla) Principal lines involve 3 components
Orbital process of zygoma Inferior rim of orbit Zygomatic arch
Main fragment is zygoma, which is separated from its three areas of attachment
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Zygomatic Fractures
Zygomatic complex fractures Fractures almost invariably traverse the infraorbital nerve foramen
(located in the orbital floor), causing impaired sensation of the cheek and a portion of the upper lip. However in majority of cases, the nerve is usually intact
Image interpretation should pay additional attention to Alignment of zygoma (depressed, rotated) Lateral orbital wall alignment (posterior relationship of zygoma and
sphenoid bones) Angulation of the wall results in increased orbital volume and
enophthalmos
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Zygomatic Fractures
Isolated zygomatic arch fracture Etiology: direct blow by small object
Commonly consists of 3 fracture lines: One at each end and the third in the center with depression of
fracture fragment
Limited motion of mandible may occur if the fracture impinges on coronoid process or simply because the masseter muscle arises from zygomatic arch
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Zygomatic Complex Fractures
60-year-old man fell onto the left cheek. Axial and coronal reformatted CT images show typical left ZMC fractures: anterior/posterior walls of maxillary sinus including rim (red arrows), zygomatic arch (green arrow), and orbital process of zygoma (blue arrow). Left orbital floor ‘blow-out’ fracture with intraorbital fat herniation is seen in coronal image. Orbital floor fracture is commonly associated with ZMC fractures.
H = Hemosinus, = Soft tissue emphysema due to communication with fractured sinus
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Zygomatic Complex Fractures
Same patient as in the previous page
3D image shows all components of left ZMC fractures including the inferior orbital rim (red arrows), zygomatico-frontal separation (blue arrow), zygomatic arch (green arrow).
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Isolated Zygomatic Arch Fractures
23-year-old man was punched by a left-handed. Classic zygomatic arch fractures occur in three sites along the arch. The middle fracture causes fracture fragment depression.
Maxillary Fractures
Types of maxillary fractures Maxillary sagittal fracture (maxillary sinus fracture)
Palate fracture
Alveolar process fracture
LeFort fractures LeFort I fracture
LeFort II fracture
LeFort III fracture
Combination (bilateral, hemi-)
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Maxillary Fractures
Maxillary sagittal fracture AKA maxillary sinus fracture
Fracture of a maxilla in sagittal plane, involving anterior-lateral wall of a maxillary sinus (LeFort fractures represent bilateral maxillary fractures)
Due to direct blow to either right or left midface
Plain film shows opacified maxillary sinus, however it is usually inadequate for diagnosis
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Maxillary Sagittal Fracture
68-year-old man was found down.
There is a sagittal plane fracture of the left maxillary sinus (red arrow) with hemosinus (H)
Maxillary Fractures
Isolated alveolar process fracture Fracture of any portion of the alveolar process
Clinically evident by malalignment and displacement of teeth contained within fractured segment
Even on CT, fracture may be subtle and easily overlooked
Further imaging may be needed when the diagnosis is made X-ray of the teeth or a panoramic view (look for dental injuries)
Chest radiograph (look for aspirated teeth)
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Maxillary Alveolar Process Fractures
Middle age women fell onto her mouth. Red arrows show the comminuted fractures of the maxillary alveolar process on the right side. These fractures are considered ‘open’ as they are connected to the oral cavity.
LeFort Fractures
Among the most severe fractures seen in face and associated with high-energy trauma
Named after René LeFort, a French physician, who studied facial fractures in cadavers. Result was published in 1901
Key facts In each type, there is a partial or complete separation of maxilla from
the remainder of the facial skeleton All LeFort fractures must extend through posterior face, transects the
pterygoid processes Any combination of LeFort I, II, and III patterns can occur
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LeFort Fractures
LeFort I fracture Definition: transmaxillary fracture
Transverse (horizontal) fracture of inferior maxillae, involving maxillary sinuses (all except superior walls), lateral margin of nasal fossa, nasal septum and pterygoid plates
Clinical: free floating and movable hard palate with maxillary teeth
Imaging findings Opacified bilateral maxillary sinuses
Transverse fracture through the inferior maxillae above hard palate
Best shown and confirmed by coronal and sagittal reformatted CT images
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LeFort I Fracture
48-year-old man was kicked by a horse. LeFort I fracture line along bilateral maxillary sinuses (red arrows). Pterygoid plate fractures are not shown H = Hemosinus, Blue arrow = Mandibular fracture
LeFort Fractures
LeFort II fracture Pyramid-shaped maxillary fracture, involving maxillary sinuses
(anterior-lateral walls), inferior orbital rim, orbital floor and nasofrontal suture
Clinical: free floating, movable midface including maxillary teeth, hard palate and nose
Imaging findings: Opacified bilateral maxillary sinuses and orbital emphysema
Fractures of anterior/lateral walls of maxillary sinuses, inferior orbital rims/floors and disruption of nasofrontal suture
Best seen and confirmed by coronal reformatted CT images
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LeFort II Fracture
Middle age man in motor vehicle accident. Fracture lines are demonstrated in red arrows. Fracture of pterygoid plates are present in all type of LeFort fractures.
H = Hemosinus
LeFort Fractures
LeFort III fracture AKA craniofacial disjunction This fracture separates calvaria (skull) from the facial bones. Most severe
of all LeFort fractures Definition: separation of facial bones from the skull
Zygomas separated from sphenoid at zygomatico-sphenoid sutures
Nasal bones and medial orbital walls separated from frontal bone at nasofrontal sutures
Best seen in coronal images
Clinical: movement of face relative to the skull Imaging findings:
Plain film will underestimate degree of injury due to severe soft tissue swelling obscuring the bony details. CT is recommended
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Combined LeFort II and III Fractures
32-year-old man, unrestrained driver in a motor vehicle accident.
Blue arrows define LeFort II fracture. Red arrows define the LeFort III fracture.
Mandibular Fractures
Motor vehicle collisions and assaults together account for more than 80% of mandible fractures
Incidence Ratio of mandibular to facial fractures = 2:1 Co-existence of mandibular and facial fractures = 6-10% Rare in children
If occurs, condyle is the most common location Condyle is the growth center of mandible. Trauma to this area can retard
growth and cause facial asymmetry
Clinical Laceration under chin (common) Pain, malocclusion, deviation of mandible on opening mouth
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Mandibular Fractures
Mandible is divided into region for purpose of describing location of fractures
Symphysis (= within the boundaries of central incisors) Parasymphysis (within the boundaries of vertical lines distal to canine
teeth) Body (include the region of third molar) Angle (distal to the third molar) Ramus Condylar process (has separate classification system) Coronoid process Alveolar process (region normally contains teeth)
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Mandibular Fractures
Relevant anatomy Mandible is a ring or arc bone which is usually difficult to break in
one location. Approximately half of mandible fractures occur in multiple locations. Search for a second fracture after initial fracture is identified!
(usually at contralateral side) In angle fracture: 3 muscles attaching to the ramus of mandible
(masseter, temporalis and medial pterygoid) pull the proximal fragment upward and medially
In symphyseal, parasymphyseal fractures: Digastric, geniohyoid and genioglossus muscles pull the symphysis downward posteriorly
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Mandibular Fractures
Imaging recommendation Plain film mandible series (PA, lateral, Towne’s and bilateral obliques)
show nearly all fractures BUT may be difficult to obtain in multi-trauma patients
Panoramic radiography (orthopantography) Need patient in upright position Better to look for subtle tooth fracture
CT Show all mandibular fractures AND other facial fractures (co-existence
6-10%), as well as position and alignment of fragments Display associated soft tissue injuries
Easy to perform in multi-trauma patient
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Bilateral Mandibular Fractures/Dislocations
Red arrows = Mandibular condyles which are located ‘too anterior’ than usual
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Bilateral Mandibular Fractures/Dislocations
Same patient as in previous page. CT shows left symphyseal/ parasymphyseal fracture extending to the tooth (green arrows), and bilateral mandibular condyle fractures (red arrows). The findings represent ‘Flail mandible’. Limitation of plain films in previous page is likely due to 1. Inadequate coverage (PA projection does not include the inferior part of mandible) 2. Suboptimal technique (Oblique views are not true oblique)
If plain film is to be used, make sure to have all projections, adequate coverage and optimal technique. If in doubt, CT is the solution
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Mandibular Fractures
43-year-old man, fell from height, presented with malocclusion Orthopantogram demonstrates a fracture of the right ramus of mandible (red arrows). Subtle ‘second’ site of fracture is at the left body (green arrows) which is confirmed in CT scan (next page).
Search for second site of fracture is warranted
when one sees mandibular fracture
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Right Sagittal
Mandibular Fractures
Same patient as in previous page. CT confirms the fractures of the right angle of mandible (red arrows) and left body (green arrows). Axial image shows extension of fracture into the root of the left mandibular tooth, indicating an open fracture
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Mandibular Fractures
21-year-old man was punched at his left face by the right-handed person. Orthopantogram shows a nondisplaced fracture of the left angle of mandible (red arrows), extending to the root of unerupted ADA #18.
Where is the second site of fracture?
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Mandibular Fractures
Same patient as previous page. CT Orthopantogram (post-processing images from axial CT) shows an additional nondisplaced fracture of the left parasymphysis (blue arrows).
Plain orthopantogram should not be used as a single imaging to look for mandibular fractures. It is useful for tooth fracture, not for mandible.
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Mandibular Fractures with TMJ Dislocation
19-year-old woman in a rollover motor vehicle accident. Axial CT image (A) shows ‘empty glenoid sign’ (red line) indicating right temporomandibular joint dislocation. Image B in a more inferior slice reveals a fracture of the right mandibular condyle (red arrow) with anterior medial displacement of the condyle due to the pull of lateral pterygoid muscle. The left glenoid fossa is normal.
C = Left condyle of mandible
A B
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Mandibular Fractures with TMJ
Dislocation
Same patient as in previous page.
3D image on right lateral view makes it easier to understand the fracture site, dislocation and orientation of the fragment.
Red arrows = fracture of the base of right condyle of mandible
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Mandibular Fractures with Tooth Fracture
Young man in a motor vehicle accident. Tooth fracture of ADA #29 is apparent (blue arrow) in this orthopantogram. However, fracture of the right body of mandible is very subtle (red arrow) and may be detected only retrospectively. This confirms that orthopantogram is not an appropriate imaging technique to rule out or characterize mandible fractures.
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Mandibular Fractures with Tooth Fracture
Same patient as in previous page. In this case, CT demonstrates comminuted fracture of the right body of mandible (red arrow) and tooth fracture (blue arrow).
Imaging Approach - Plain Film
Friendly line (anterolateral antral wall of maxillary sinus) Both intact
NO ZMC or LeFort fractures
Blowout fracture
Isolated fractures of lateral orbital wall, zygomatic arch
One disrupted ZMC fractures
Maxillary sagittal fracture (isolated sinus fracture)
Both disrupted LeFort fractures
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Imaging Approach - CT
Clear sinus sign (= all sinuses and mastoid are clear of fluid), there are three possible facial fractures: Nasal bone fractures
Isolated zygomatic arch fractures
Mandible fractures
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Imaging Approach - CT
Bloody sinuses Pterygoid plate fracture present - probable LeFort fracture
With fracture of lateral margin of nasal fossa = LeFort I
With fracture of inferior orbital rim = LeFort II
With fracture of zygomatic arch = LeFort III
Maxillary wall fractures
Orbital floors, NOE region fractures
ZMC fractures
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Checklist for Facial Radiograph/CT
Treat life-threatening injury first (ABC of trauma)
CT is more accurate, faster to do than plain films and can be performed at the same time as trauma head CT
Facial structures are quite symmetrical
Do not stop searching when see one abnormality
If suspect for more than simple nasal fracture, do CT
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Checklist for Facial Radiograph/CT
Significant (but can be subtle) fractures Fracture involves the optic foramen which can cause permanent
visual loss if not treated promptly
Fracture of the posterior wall of frontal sinus requires neurosurgical evaluation and may require antibiotics prophylaxis
Fracture/dislocation of the TMJ usually missed on initial survey. It can cause significant disability if left untreated
Look for significant soft tissue injuries Globe rupture, hemorrhage
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Checklist for Facial Radiograph/CT
Emergency in face injury Airway compromise due to severe soft tissue swelling, fracture
or obstructed foreign body
Life threatening hemorrhage can be from nasal injury
Facial fractures that compromise vision Orbital apex fracture may injure optic nerve, requiring urgent Rx
Entrapment of intraocular muscle requires urgent Rx
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The information provided in this presentation… Is intended to be used as educational purposes only.
Is designed to assist emergency practitioners in providing appropriate radiologic care for patients.
Is flexible and not intended, nor should they be used to establish a legal standard of care.
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