imaging of facial trauma

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Imaging of Facial Trauma

Rathachai Kaewlai, MD Division of Emergency Radiology, Ramathibodi Hospital, Mahidol University, Bangkok Emergency Radiology Minicourse 2014

Updated May 2014


Before We Start…

•  Facial x-ray is overrated •  CT is the current standard for most facial fracture imaging beyond

nasal bone •  Still, we need to learn both XR and CT •  Key for XR: Hazy sinuses, Lines of Dolan •  Key for CT: urgent findings, significant soft tissue injuries, fracture

pattern recognition


Facial Bones http://encyclopedia.lubopitko-bg.com/Axial_Skeleton.html


Facial Buttresses: 4 Vertical


Facial Buttresses: 5 Transverse

1 superior orbital rim

2 inferior orbital rim

3 maxillary alveolar rim

4 mandibular alveolar rim

5 inferior border of mandible


Facial Segments

Upper Face: frontal, superior orbit (part of skull)

Lower Face : mandible

Mid Face: other orbit, nasal, zygoma, Le Fort, maxillary sinus, dentoalveolar, NOE, ZMC

11%

70%

19%

% indicate distribution of facial fractures Ref: Mundinger et al. J Craniomaxillofac Surg 2014


About Facial Trauma

•  Mundinger J Craniomaxillofac Surg 2014 (n = 8127) –  Male 77.6% –  Right 28%, midline 36%, left 36% –  One fracture pattern 52% (most common = nasal #) –  Panfacial injury 1.1% –  Bilateral fractures 18.9% –  Association:

•  C-spine fracture 6.6% •  Skull base fracture 7.6% (greatest in Le Fort II, III or any Le Fort

combinations)


Role of Imaging

•  Detection of soft tissue and bony injuries •  Characterization of soft tissue and bony injuries •  Surgical planning •  CT preferred over x-ray

–  Much more accurate than x-ray –  Easier to perform in multi-trauma, non-cooperative patients –  If patients going to have CT for other indications –  If you think of injury other than simple nasal fracture


Wisconsin Criteria

•  For obtaining facial CT in multi-trauma patient •  Any 1 of 5 criteria

–  98% sensitive for presence of fracture –  88% NPV for all fractures –  Reduce CT use by 9%

•  Bony stepoff or instability •  Periorbital swelling or contusion •  GCS <14 •  Malocclusion •  Tooth absence Sitzman et al. Plast Reconstr Surg 2011


Standard X-ray Projections

•  Facial trauma series –  AP/PA –  Caldwell’s –  Water’s –  Towne’s –  Lateral –  (+/- base)

a

5-6 views


Standard X-ray Projections

•  Mandible trauma series –  AP –  Lateral –  Towne’s –  Both obliques

5 views


Interpreting Facial X-rays

•  Hazy PNS •  Lines of Dolan

–  AKA: Elephant head (Lee Rogers) –  Water’s view

Water view is the cornerstone


Don’t Rely on X-rays Too Much, Use CT Liberally

Unilateral NOE fracture ZMC fracture


CT Techniques: Facial CT Extended Brain CT

•  Smaller FOV •  Frontal sinus to mandible •  Nose to mandibular condyles •  Thinner collimation

–  1 mm bone –  2 mm soft tissue

•  2D (coronal and sagittal) reformats, and 3D shaded surface display -- routine


Imaging Approach: CT Specifically search for urgent findings

Fracture No fracture

Nasal Zygomatic arch

Mandible Dento-alveolar

Le Fort I, II, III ZMC, frontal

Maxillary Orbit NOE

Airway Vision

No Yes

Clear paranasal sinus?

Pterygoid plates?


Airway Compromise: Nasal Septal Hematoma

•  Usually clinically apparent •  Must be identified quickly

–  Epistaxis can be life threatening –  May lead to compromised nasal

airway –  Late complications: infection,

abscess, necrosis -> saddle nose deformity


Airway Compromise: Flail Mandible

•  Fractures of symphysis + bilateral condyles, rami or angles

•  Airway may be occluded 2/2 –  Large pharyngeal hematoma –  Inability to maintain tongue in anterior

position in supine patient


Vision Compromise: Globe Rupture •  Full-thickness scleral or

corneal wound •  Common at anterior surface of

eye but can be clinically occult in posterior

•  CT to assist in diagnosis* –  Sensitivity 60-75% –  Specificity 76-100%

•  CT to identify foreign bodies and concomitant injuries

*Romaniuk Emerg Med Clin N Am 2013 Intraocular air and foreign body

Extruded vitreous and intraocular air


Vision Compromise: Globe Rupture •  Change of globe contour with

loss of volume “Flat-tire” sign •  Scleral discontinuity •  Intraocular air •  Intraocular foreign body •  Indirect signs: lens

displacement into vitreous

Narrow anterior chamber

Contour abnormality “Flat-tire” sign. Green arrows = trapped extraocular air


Vision Compromise: Orbital Apex Fracture

•  Optic canal can be fractured causing traumatic optic neuropathy and vision loss

•  True emergency if there is radiological and clinical evidence of optic nerve impingement

Image from medscape.com

Orbital apex fracture


Vision Compromise: Lens Injuries •  Tear of zonular fibers that hold

lens to ciliary muscles •  Luxation •  Dislocation •  Traumatic cataract •  If bilateral, think collagen

vascular disease or homocysteinuria

Diagram: getsomenbeo.wordpress.com Rt: Lens subluxation. Lt: Lens dislocation


Vision Compromise: Ocular Detachments •  Laceration of 3 layers of globe

leading to fluid collections •  Retinal detachment

–  Retinal separated from choroid –  Vitreous in subretinal space –  Possibility of non-accidental

trauma in children –  V-form with apex at optic disk and

anterior part at ora serrata

•  Choroidal detachment –  Collection in suprachoroidal space

between choroid and sclera –  Biconvex lens shape

Choroidal detachment

Retinal detachment


Vision Compromise: Retrobulbar Hemorrhage

•  Increased IOP transmits to optic nerve and globe compression of retinal vessels retinal ischemia loss of vision in 60-100 min

•  “Orbital compartment syndrome” •  Arterial bleeding from infraorbital

or ethmoidal arteries •  Severe proptosis, tented

posterior sclera and stretched optic nerve

•  Discrete hematoma rarely seen •  Common associated orbital/

facial/cranial injuries

Retrobulbar hemorrhage with medial orbital wall fracture


Nasal Fracture

•  Most common site of facial # •  Frontal blow, lateral blow, blow from below •  Clinical diagnosis

–  X-ray misses up to half –  When isolated, XR may be adequate –  X-ray views: laterals and Water

•  CT when concern more than mere nasal fracture


Nasal Fracture

•  What are features of #? –  Unilateral or bilateral –  Simple vs. comminuted

•  If comminuted, is there telescoping or depression?

•  Is nasal septum involved? –  Fracture or hematoma or both

•  What other fractures does the patient have? –  Frontal process of maxilla –  ZMC –  NOE

Patel et al. Semin Ultrasound CT MRI 2012

Bilateral nasal bone fractures with comminution and depression on the right side. No telescoping or

septal involvement


Zygomatic Arch Fracture

•  Three fracture lines: one at each end and third in the center

•  Limited motion of mandible (trismus) by –  Impinged coronoid process –  Masseter origins


Mandible Fracture

•  Typical bilateral injury pattern –  Force transmitting on U-shaped mandible,

producing bilateral # –  Must always search for 2nd fracture –  42% unifocal*

•  7 anatomic regions –  Symphysis/parasymphysis –  Alveolar process –  Body –  Angle –  Ramus –  Coronoid –  Condyle: head, neck, subcondyle

*Murray et al. Emerg Med Clin N Am 2013

http://dermatologic.com.ar/7.htm


Mandible Fracture

•  Forced occlusion: TMJ or condylar area •  Blow from lateral or frontolateral: body or angle # •  # often displaced because of traction of attached muscles

Gray’s Anatomy


Mandible Fracture

•  X-ray –  PA view: rami, body –  Towne view: condyles, rami, TMJ –  Lateral & oblique views: body, angle

•  Panoramic x-ray –  Rami and condyles –  Tooth –  Not always available in emergency

setting


Mandible Fracture

•  CT is the imaging modality of choice •  Suggested approach:

–  Cooperative patient screening XR + panoramic UNLESS 1) suspected other injuries, 2) will get CT for other indications

–  Un-cooperative patient CT


Dentoalveolar Fracture

•  Universal Numbering System (American Dental Association: ADA) for secondary teeth 1-32

•  Crown (above gingiva) + root (in alveolar bone) •  Tooth injuries

–  Luxation •  Complete (avulsion) vs. partial

–  Subluxation –  Fracture

http://www.simplestepsdental.com/i/D/DNTKnowUnivNumSys.gif


Dentoalveolar Fracture

•  Any portion of alveolar process •  Maligned and displaced teeth •  Further imaging:

–  Tooth x-ray (?fracture) –  CXR (?aspirated teeth)

Maxillary dentoalveolar process fracture





Mandible

Le Fort I, II, III ZMC, frontal

Maxillary Orbit NOE

Airway Vision

No Yes


Pterygoid plates?


Pterygoid Plate Fracture

•  90-100% Le Fort # •  Isolated pterygoid plate

fracture very rare

•  Absence of pterygoid plate # rules out Le Fort


Le Fort Fractures

•  Among the most severe facial fractures •  Progressively severe category from I III •  Separation (partial or complete) of maxilla from remainder face •  All extend through posterior face transecting pterygoid plates •  I, II, III and combined

Hopper RA, et al. Radiographics 2006


Le Fort I Fracture

•  Transverse fracture of inferior maxillae (involving all walls of maxillary sinus except superior walls), nasal septum and pterygoid plates

•  Free-floating hard palate


Le Fort I Fracture

Diagram from Hopper RA, et al. Radiographics 2006


Le Fort II Fracture

•  Pyramid-shaped •  Fractures of

–  Maxillary sinuses anterolateral wall

–  Inferior orbital rim –  Orbital floor –  Nasofrontal suture

•  Free-floating midface


Le Fort II Fracture



Le Fort III Fracture

•  Most severe of all Le Fort •  Separation of facial bones from

skull “craniofacial separation” –  Zygoma separates from

sphenoid –  Nasal bones and medial orbits

separated from frontal bone

Combined Le Fort II and III


Le Fort III Fracture (with I & II)






Mandible

Le Fort I, II, III Frontal NOE Orbit ZMC

Maxillary

Airway Vision

No Yes


Pterygoid plates?


Hazy Sinus + Intact Pterygoid Plates: DDx •  Frontal sinus fractures •  Naso-orbital-ethmoidal (NOE) fractures •  Orbital fractures •  Zygomaticomaxillary complex (ZMC) fractures •  Maxillary sinus fractures


Frontal Sinus Fracture

•  Anterior table –  Thicker, require strong force to break –  Cosmetic

•  Posterior table –  Dural tear – CSF leak –  Brain injury

•  Floor: superior orbital rim & medial orbital roof –  Nasofrontal duct or frontal recess

www2.aofoundation.org

NFD or frontal recess (dotted lines), a = Agger nasi http://www.asnr.org/neurographics/Smith/2.shtml


Frontal Sinus Fracture

•  Strong suspicion for NFD injury if: –  # fragments in nasofrontal outflow tract –  Frontal sinus floor # –  # medial wall of anterior table

•  Checklist –  Which tables are involved? –  Is there significant displacement or

comminution of either table? –  Are there signs of NFD occlusion? –  Are there associated intracranial

abnormality to suggest dural violation?


Naso-orbital-ethmoidal (NOE) Fracture

•  Fracture disrupting: Medial orbit + nose + ethmoid sinuses

Hazy maxillary and ethmoid sinuses


Naso-orbital-ethmoidal (NOE) Fracture

•  Medial canthal tendon slings globe to medial orbital wall

•  In NOE fracture, the tendon pulls fragment laterally causing telecanthus

•  Simple vs. comminuted •  Disrupted vs. non-disrupted medial canthal

tendon

Medial canthal tendon

Gray’s Anatomy


Orbital Fracture

•  Can be isolated or with other facial fractures (NOE, ZMC, Le Fort)

•  Blow out vs. blow in –  Blow out: bone displaced away from orbit due

to sudden pressure changes in orbit –  Blow in: bone displaced into orbit from direct

PNS injury

Rad.washington.edu

Blow in fracture

Blow out fracture


Orbital Fracture: EOM Entrapment

Normal Hooked Entrapped

Shape of IOM Flat Oval Round

Location of IOM Not in defect Portion lies within defect

Whole muscle beneath/within defect

Clinical eye exam required Easily missed entrapped inferior rectus in children because fragment springs back into place “trapdoor”


Orbital Fractures

•  X-ray false negative 7%-30% •  Up to 30% have ocular injury


Orbital Fracture: Medial Wall

•  Entrapment of medial rectus results in horizontal motility restriction

•  Loss of normal posteromedial bulge of orbit

•  Check for NOE # and nasofrontal duct disruption


Orbital Fracture: Checklist

•  Is the fracture large (> 1 cm2 of floor)? •  Are orbital contents displaced? •  Are there signs of EOM entrapment? •  Are there associated ocular injuries? •  Are there associated intracranial injuries?


Zygomaticomaxillary Complex (ZMC) Fracture

•  4 principle fracture lines: –  Lateral orbital rim –  Zygomatic arch –  Zygomaticomaxillary buttress –  Inferior orbital rim

Diagrams from Buchanan EP, et al. Plast Reconstr Surg 2012


ZMC Fracture

•  4 principle fracture lines: –  Lateral orbital rim –  Inferior orbital rim –  Zygomatic arch –  Zygomaticomaxillary buttress


ZMC Fracture

•  2 of 4 are orbital structures –  # orbital volume and contents can be

affected –  Globe, nerve, EOM –  Orbital apex

•  Can cause impaired mandible motion esp. if depressed

•  Infraorbital nerve foramen

Decreased orbital volume

Compression of temporalis muscle


Maxillary Sagittal Fractures:

•  Types of maxillary sinus fractures: Maxillary sagittal, palate, alveolar process, Le Fort

•  Maxillary sagittal #: anterior wall only (normal pterygoid, zygomatic arch)


Multiple Patterns

•  Nasal + NOE •  Nasal + ZMC •  Nasal + frontal process of

maxilla •  ZMC + orbit •  Le Fort + ZMC •  Le Fort + NOE •  etc...


Panfacial Injuries

•  At least one fracture in all of 3 facial thirds


Conclusion

•  Facial fracture concomitant with mandible fracture 6-10%; facial CT must include mandible and vice versa

•  Two critical areas – airways and orbits •  Sinus haziness important sign on x-ray •  CT useful if suspected more than nasal fracture •  Clear sinus? •  Pterygoid fracture? •  Pattern recognition •  Try to fit all fractures into one pattern (if possible) in the conclusion

of the report


Disclaimer

•  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 be used to establish a legal

standard of care

imaging of facial trauma

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