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Imaging of Facial Trauma Part 1: Introduction and Anatomy

Rathachai Kaewlai, MD

www.RadiologyInThai.com

Created: January 2007

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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

  Naso-orbital-ethmoid 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

  Co-existence of other injury

  3-14% of patients with facial fracture have skull fractures

  1-4% 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   Reasons: 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

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When to Do Imaging of the Face?

  Head CT should be thoroughly evaluated in a multi-trauma 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 cost-saving screening exam when compared to multiple views of plain film radiography*

  Radiation dose is far below the threshold for cataract formation

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*Turner BG et al. AJR Am J Roentgenol 2004;183:751-754

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)

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FACE

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3D CT Anterior View

Major structures are labeled in the picture.

Nasofrontal suture Zygomatico-frontal suture Zygomatico-temporal suture

SOF = Superior orbital fissure IOF = Inferior orbital fissure

Orbital ‘rim’ is different from the ‘wall’

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3D CT Left Lateral View

Nasofrontal suture Zygomatico-frontal suture Zygomatico-temporal suture

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3D CT Base View

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   Pre-surgical planning for complex injuries

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

additional orthopanthogram 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 structures A = Frontal sinus, anterior wall B = Frontal sinus, posterior wall

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

•  Posterior wall of frontal sinus fracture may co-exist with brain injury •  Presence of pneumocephalus signifies dural tear related with the fracture •  Inferior part of frontal sinus constitute the medial orbital wall

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Key structures D = Orbit, medial wall E = Orbit, lateral wall F = Suture between sphenoid and zygomatic bones

= Nasomaxillary suture

1 = Globe 2 = Ethmoid sinus 3 = Sphenoid sinus 4 = Nasal bone 5 = Maxilla, frontal process 6 = Orbit, lateral rim 7 = Sphenoid bone 8 = Optic foramen

•  Do not misinterpret 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 structures F = Groove for infraorbital nerve G = Maxillary sinus, posterolateral wall 5 = Maxilla, frontal process 9 = Maxillary sinus 10 = Zygomatic arch 11 = Pterygoid bone 12 = Nasolacrimal duct 13 = Mandible, condyle

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

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Key structures H = Maxillary sinus, anterior wall I = Maxillary sinus, medial wall J = Medial pterygoid plate K = Lateral pterygoid plate

9 = Maxillary sinus 14 = Mandible, ramus

Fracture of the pterygoid plates may represent LeFort fracture

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Key structures J = Medial pterygoid plate K = Lateral pterygoid plate L = Maxilla, spine

14 = Mandible, ramus 15 = Maxilla bone/ hard palate

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

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Key structures L = Maxilla, spine

= Nasomaxillary suture

4 = Nasal bone 5 = 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 Image

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Key structures D = Orbit, medial wall M = Nasal septum

5 = Maxilla, frontal process 15 = Maxilla bone/ hard palate 16 = Frontal sinus 17 = Mandible, body

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Key structures M = Nasal septum N = Ethmoid bone, perpendicular plate O = Orbit, roof P = Orbit, floor Q = Maxillary sinus, posterolateral wall = Zygomatico-frontal suture

1 = Globe 2 = Ethmoid sinus 6 = Orbit, lateral rim 9 = Maxillary sinus

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Key structures J = Medial pterygoid plate K = Lateral pterygoid plate N = Ethmoid, perpendicular plate

3 = Sphenoid sinus 10 = Zygomatic arch 14 = Mandible, ramus 18 = Mandible, angle

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Key structures R = Temporomandibular joint (TMJ)

13 = Mandible, condyle 14 = Mandible, ramus 19 = Mandible, coronoid process 20 = 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 Image

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Key structures P = Orbit, floor

7 = Pterygoid bone 9 = Maxillary sinus 15 = Maxilla bone /hard palate

•  Orbital blowout fracture is best seen in sagittal and coronal images •  Facial CT is not completed without image (2D) reformations

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Key structures 3 = Sphenoid sinus 4 = Nasal bone 15 = 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 rectus LR = Lateral rectus IOL = Intra-ocular lens

•  Globe contour should be smooth •  Clean (dark) retro-bulbar fat

Axial Coronal

Sagittal

  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.

  Thanks, MGH Radiology, for cases I’ve seen and things I’ve learned.

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R.K.