imaging of facial trauma part 1

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Emergency Radiology: Imaging of Facial Trauma Rathachai Kaewlai, MD

Imaging of Facial TraumaPart 1: Introduction

Rathachai Kaewlai, MDSpecialized in Body Imaging and Emergency Radiology

[email protected] January 2007

The author is willing to receive any input, comments and corrections, Please do not hesitate to contact at the email address provided above.

mailto:[email protected]

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Outline

• Facial fracture epidemiology• Initial management• Imaging: CT versus

radiography• Normal anatomy

– 3D– CT (axial, coronal and

sagittal planes)– Radiography

• Biomechanics

• Types of facial fracture– Nasal bone fracture– Nasoorbitalethmoid

fracture– Frontal sinus fracture– Orbital fracture– Zygomatic fracture– Maxillary fracture– Mandibular fracture

• Imaging approach

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Epidemiology

• Etiology (USA)– Motor vehicle collision (MVC) most common cause– Followed by fights, assaults– Less common: fall, sports activities, industrial accidents, gun shot

wounds• Soft tissue injury is more common than fracture• Coexistence of other injury

– 314% of patients with facial fracture have skull fractures– 14% of patients with facial fracture have cervical spine fractures– 20% of patients with cervical spine fractures have facial injury (half

soft tissue injuries, half fractures)

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Epidemiology

• Distribution of fracture– Vary with mechanism of injury– In general, most common facial fracture is nasal bone fracture– Most common fracture in admitted patients is zygomatic complex

(ZMC) fracture at 40%, followed by complex fractures such as LeFort fracture

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Epidemiology

• Facial fracture in children– Less common (< 10% of all facial fractures occur in children)– Less severe than adults– Most common etiology is fall– Reason: midface is less prominent, sinuses are less pneumatized,

more elasticity of bones– Fractures that are more frequent in children than in adults

• Mandibular condyle• Orbital roof

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ABC of Trauma

• Initial patient management is to secure airway (A), breathing (B) and circulation (C)

• Evaluation of more serious injuries of the head, chest and abdomen

• Avoid blind insertion of endotracheal tube and nasogastric tube• Significance of facial trauma for the initial management

– Facial fractures may impinge on oral or nasal airway– Nasal bleeding may be life threatening– Mandible fractures may cause loss of support for tongue, then

airway compromise – Facial fractures may compromise vision

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When to Do Imaging of the Face?

• When the patient is stabilized– Clinically (Airway, Breathing, Circulation stable),

• Initial goal is to preserve life then later restore the form and function of the face

• Cervical spine clearance– Radiographically

• For cervical spine clearance• Head CT should be thoroughly evaluated in a multitrauma

patients – Search for critical, emergent finding: some facial injuries may

compromise vision if not immediately recognized– In stable patient, face CT can be performed with little additional

time when the patient is already in the scanner

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What Imaging to Do?

• Role of imaging– Identify fractures, fragment displacement and rotation, stable bone

for use in surgical repair– Identify soft tissue injuries

• CT is the imaging modality of choice because– High accuracy for evaluation of both bony and soft tissue injuries– Can be costsaving screening exam when compared to multiple

views of plain film radiography*– Radiation dose is far below the threshold for cataract formation

*Turner BG et al. AJR Am J Roentgenol 2004;183:751754

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Normal Anatomy

• Face– Face (midface) is the region

from supraorbital rims to and including maxillary alveolar process

– Mandible, including the temporomandibular joints (TMJ), considered separate from the face

– This lecture series will include both parts (face and mandible)

FACE

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3D CTAnterior View

Major structures are labeled in the picture.

Nasofrontal suture Zygomaticofrontal

suture Zygomatico

temporal suture

SOF = Superior orbital fissureIOF = Inferior orbital fissure

Orbital ‘rim’ is different from the ‘wall’

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3D CTLeft Lateral View

Nasofrontal suture Zygomaticofrontal suture Zygomaticotemporal suture

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3D CTBase View

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Computed Tomography (CT)

• Preferred modality for imaging of the face– More sensitive for fracture detection – Show significant soft tissue injury, especially the globe– Easier to perform, quicker than complete views of plain film

radiographs– Presurgical planning for complex injuries– Low radiation dose– ? Lower cost ?

• Disadvantage of CT– CT can miss subtle tooth fracture along the axial plane,

additional orthopanthogram (Panorex ®) may be helpful to detect tooth fracture

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Computed Tomography (CT)

• CT protocol– Axial scanning from above the frontal sinus down to below hard

palate (face), and can be scanned further to include the mandible, if there is a clinical suspicion for fracture of mandible

– For helical (spiral) scanner, axial images can be reconstructed to coronal and sagittal planes without the need for direct coronal scanning

– Viewing in both bone and soft tissue windows, in 3 planes (axial, coronal and sagittal)

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Key structuresA = Frontal sinus, anterior wallB = Frontal sinus, posterior wall

*Note: The right frontal sinus is not pneumatized in this case.

• Posterior wall of frontal sinus fracture may coexist with brain injury • Presence of pneumocephalus will signify dural tear related with the fracture• Inferior part of frontal sinus constitute the medial orbital wall

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Key structuresD = Orbit, medial wallE = Orbit, lateral wallF = Suture between sphenoid and zygomatic bones = Nasomaxillary suture

1 = Globe2 = Ethmoid sinus3 = Sphenoid sinus4 = Nasal bone5 = Maxilla, frontal process6 = Orbit, lateral rim7 = Sphenoid bone8 = Optic foramen

• Do not confuse the suture between nasal bone and frontal process of maxilla for a fracture• Look for a piece of fracture in the optic foramen, it is the true emergency of facial fracture

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Key structuresF = Groove for infraorbital nerveG = Maxillary sinus, posterolateral wall5 = Maxilla, frontal process9 = Maxillary sinus10 = Zygomatic arch11 = Pterygoid bone12 = Nasolacrimal duct13 = Mandible, condyle

Clear maxillary sinuses can almost rules out certain fractures such as ZMC, LeFort, blowout fractures

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Key structuresH = Maxillary sinus, anterior wallI = Maxillary sinus, medial wallJ = Medial pterygoid plateK = Lateral pterygoid plate

9 = Maxillary sinus14 = Mandible, ramus

Fracture of the pterygoid plates may represent LeFort fracture

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Key structuresJ = Medial pterygoid plateK = Lateral pterygoid plateL = Maxilla, spine

14 = Mandible, ramus15 = Maxilla bone/ hard palate

Lucency in midline of the maxilla is a normal finding seen occasionally

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Key structuresL = Maxilla, spine = Nasomaxillary suture

4 = Nasal bone5 = Maxilla, frontal process

• Do not confuse nasomaxillary suture for a fracture• Remind yourself that CT can miss subtle tooth fracture, although with the coronal and sagittal reformation. Obtain orthopanthogram or dedicated tooth film when in doubt

Coronal Reformatted Images

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Key structuresD = Orbit, medial wallM = Nasal septum

5 = Maxilla, frontal process15 = Maxilla bone/ hard palate16 = Frontal sinus17 = Mandible, body

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Key structuresM = Nasal septumN = Ethmoid bone, perpendicular plateO = Orbit, roofP = Orbit, floorQ = Maxillary sinus, posterolateral wall

= Zygomaticofrontal suture

1 = Globe2 = Ethmoid sinus6 = Orbit, lateral rim9 = Maxillary sinus

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Key structuresJ = Medial pterygoid plateK = Lateral pterygoid plateN = Ethmoid, perpendicular plate

3 = Sphenoid sinus10 = Zygomatic arch14 = Mandible, ramus18 = Mandible, angle

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Key structuresR = Temporomandibular joint (TMJ)

13 = Mandible, condyle14 = Mandible, ramus19 = Mandible, coronoid process20 = Mastoid air cells

If patient opens his/her mouth during the scan, there is a normal anterior gliding of the mandibular condyle relative to the glenoid fossa. That can look like subluxation of the TMJ

Sagittal Reformatted Images

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Key structuresP = Orbit, floor

7 = Pterygoid bone9 = Maxillary sinus15 = Maxilla bone /hard palate

• Orbital blowout fracture is best seen in sagittal and coronal images• Facial CT is not completed without image reconstruction

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Key structures3 = Sphenoid sinus4 = Nasal bone15 = Maxilla bone/ hard palate

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CT Orthopanthogram

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Right Orbit, soft tissue window

Key structures:ON = Optic nerve MR = Medial rectusLR = Lateral rectus IOL = Intraocular lens

• Globe contour should be smooth• Clean (dark) retrobulbar fat

Axial Coronal

Sagittal

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Plain Film Radiography

• Can be obtained to screen for facial injury if CT is not immediately available

• If plain film identify a fracture other than a simple nasal bone fracture, further evaluation by CT is indicated

• Multiple plain film projections are relative to ‘canthomeatal line’; an imaginary line drawn from outer canthus to external auditory meatus

• Proper positioning (of patient’s head), alignment of xray beam is critical for evaluation because facial skeletal anatomy is complex

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• Remember: plain film is a 2D image of a 3D object– Overlapping structures significantly obscure anatomic detail– This problem is solved by standard views (to minimize overlap,

allow visualization of important structures, familiarity for interpretation)

• Rule of symmetry: two sides of the face are quite symmetrical– Symmetry is usual, and asymmetry is suspect

• Multiplicity: fractures of facial bones are frequently multiple. Do not stop looking for others when see one

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• Facial series– Water’s view (PA view with cephalad angulation)– Caldwell view (PA view)– Towne’s view– Lateral view– Base view

• Additional view– Lateral view of the nasal bone (nasal technique)

• Mandible– Oblique view, Towne’s view– Orthopanthogram

Note: The lecture series will be focused on CT scan

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The most comprehensive single projection displayExcellent view of Maxilla Maxillary sinuses Zygoma Zygomatic arches Rims of orbits, esp. floor Nasal bones

Water’s View

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Key structures 1 = Frontal sinus2 = Maxillary sinus3 = Frontal process of Zygoma4 = Body of Zygoma (malar eminence)5 = Temporal process of Zygoma

Dotted line = zygomaticofrontal suture

Dolan’s lines of referenceLine A, B, C

Water’s View

Rule: smooth, nondisrupted, same contour on both sides

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Line A Begins at inner surface of zygomaticofrontal suture, follows orbital surface of zygoma, maxilla, frontal process of maxilla and arch of nasal bone If drawn to both sides, the line is similar to lazy ‘W’ or half frame of reading glasses

Line BBegins at lateral and inferior margin of maxilla and extends along lateral wall of maxillary sinus and inferior surface of zygomatic arch Ends at glenoid fossa

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Line C Begins at lateral and inferior margins of maxilla, extends along lateral wall of maxillary sinus and inferior surface of zygomatic arch Ends at glenoid fossa

“Friendly Line” Medial half of Line C is the anterolateral wall of the maxillary sinus. If it is disrupted, the possibilities of fx include 1) Isolated maxillary antrum 2) Zygomaticomaxillary complex (ZMC) 3) LeFort (unilateral or bilateral)

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Excellent view of Entire rim of orbit, esp. superomedial rim Ethmoid sinus Floor of orbit may be well seen in petrous bones are projected below the inferior orbital rim (not in this example)

Caldwell’s View

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Key structures1 = Ethmoid sinuses2 = Orbit

Line A, B, C, D = superior, lateral, inferior and medial walls of the orbit, respectively

Line E = midline nasal septum and vomer

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Rule: Ethmoid sinuses density should be equal, darker than orbit Smooth nondisrupted orbital walls

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Excellent view of Frontal sinus: anterior wall Maxillary sinus: anterior and posterior wall Sphenoid sinus Pterygoid plate Floor of anterior cranial fossa, hard palate Lateral rim of orbit

Lateral View

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Key structures1 = Frontal sinus2 = Maxillary sinus3 = Sphenoid sinus4 = Hard palate5 = Anterior wall of temporal fossaBetween green arrows = Pterygoid plate

Line A = Anterior wall of frontal sinusLine B = Anterior cranial fossaLine C = Anterior wall of maxillary sinusLine D = Posterior wall of maxillary sinus

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Line A Connects anterior surface of frontal sinus and anterior surface of hard palateLine B Connects anterior wall of temporal fossa and posterior edge of hard palateLine C Along planum sphenoidaleLine D Along hard palate

Rule: Line A & B parallel Line C & D parallel

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Excellent view of Maxillary sinus: posterolateral wall Zygomatic arch

Towne’s View

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Key structures1 = Zygomatic arch

Line A = Posterolateral wall of maxillary sinus

Rule: Smooth, nondisrupted line

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Orthopanthogram or Panorex® Key structuresR = Temporomandibular joint13 = Mandible, condyle 14 = Mandible, ramus 17 = Mandible, body18 = Mandible, angle 19 = Mandible, coronoid process 20 = Mandible, symphysis

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Counting the teeth on Orthopanthogram or Panorex® American Dental Association (ADA) system preferred because you will speak same ‘language’ with dentistsCount from midline and go laterally (some individuals may not have #1, #16, #17, and #32)

Maxillary Arch ADA#1 8 (right), #916 (left)Mandibular Arch ADA#3225 (right), #2417 (left)

8 9

25 24

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Oblique View of Mandible Key structuresR = Temporomandibular joint13 = Mandible, condyle 14 = Mandible, ramus 17 = Mandible, body18 = Mandible, angle 19 = Mandible, coronoid process 20 = Mandible, symphysis

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Biomechanics

• LeFort described areas of relative strength within the facial skeleton– Alveolar process of maxilla

(1)– Frontal process of maxilla (2)– Body of zygoma or malar

eminence (3)• Line of fracture tends to avoid

these areas

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Checklist for Facial Radiograph/CT

Facial structures are quite symmetrical Do not stop searching when see one abnormality If suspect for more than simple nasal fracture, do 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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• The information provided in this presentation…– Does not represent the official statements or views of the Thai

Association of Emergency Medicine. – 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.

imaging of facial trauma part 1

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