Imaging Of Facial Trauma Part 3 (2) 2


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Concluding the last portion of imaging of facial trauma.

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Imaging Of Facial Trauma Part 3 (2) 2

  1. 1. Imaging of Facial Trauma Part 3: Pathology (Zygomatic, Maxillary and Mandibular Fractures) Rathachai Kaewlai, MD Created: January 2007 1
  2. 2. Outline   Facial and mandibular fractures   Nasal fractures   Naso-orbital-ethmoidal fractures   Frontal sinus fractures   Orbital fractures   Zygomatic fractures   Maxillary fractures   Mandibular fractures   Imaging approach 2
  3. 3. 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 3
  4. 4. 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 4
  5. 5. 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 5
  6. 6. 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 6
  7. 7. 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 7
  8. 8. 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). 8
  9. 9. 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. 9
  10. 10. 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-) 10
  11. 11. 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 11
  12. 12. 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) 12
  13. 13. 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) 13
  14. 14. 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. 14
  15. 15. 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 15
  16. 16. 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   16
  17. 17. 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 17
  18. 18. 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 18
  19. 19. 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 19
  20. 20. 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 20
  21. 21. 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. 21
  22. 22. 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 22
  23. 23. 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)   23
  24. 24. 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 24
  25. 25. 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 25
  26. 26. Bilateral Mandibular Fractures/Dislocations Red arrows = Mandibular condyles which are located ‘too anterior’ than usual 26
  27. 27. Bilateral Mandibular Fractures/Dislocations Same patient as in previous page. If plain film is to be used, CT shows left symphyseal/ parasymphyseal fracture extending to the tooth make sure to have all (green arrows), and bilateral mandibular condyle fractures (red arrows). The projections, adequate findings represent ‘Flail mandible’. coverage and optimal Limitation of plain films in previous page is likely due to 1. Inadequate technique. If in doubt, CT is coverage (PA projection does not include the inferior part of mandible) 2. the solution Suboptimal technique (Oblique views are not true oblique) 27
  28. 28. Mandibular Fractures 43-year-old man, fell from height, presented with Search for second site of malocclusion fracture is warranted Orthopantogram demonstrates a fracture of the right when one sees ramus of mandible (red arrows). Subtle ‘second’ site of mandibular fracture fracture is at the left body (green arrows) which is confirmed in CT scan (next page). 28
  29. 29. 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 29
  30. 30. 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? 30
  31. 31. 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. 31
  32. 32. B A 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 32
  33. 33. 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 33
  34. 34. 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. 34
  35. 35. 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). 35
  36. 36. 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 36
  37. 37. 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 37
  38. 38. 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 38
  39. 39. 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 39
  40. 40. 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 40
  41. 41. 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 41
  42. 42.   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. 42