Saturday, October 29, 2016 Maxillofacial Injuries Practical Tips Suyash Mohan MD, PDCC THE ROOTS OF PENN RADIOLOGY RADIOLOGICAL Assistant Professor of Radiology Assistant Professor of Neurosurgery Neuroradiology Division Department of Radiology University of Pennsylvania EXCELLENCE
Maxillofacial injuries The bones of the skull and face collectively make up the most complex area of skeletal real estate in the body Analysis of the facial injuries requires: 1. Knowledge of normal anatomy 2. Knowledge of common fracture patterns Pearls: 1.Orbits (60-70%) Isolated/ complex fractures 2.Symmetry is your friend 3.Coronal CT 4.Direct/ indirect signs
Maxillofacial trauma Broadly divided into fractures involving 1. Upper face: ~ 5% 1. Frontal bone 2. Supraorbital rim 2. Midface: ~ 70% of all maxillofacial fractures 1. Nasal 2. Orbital 3. Maxillary 4. Zygomatic injuries 5. Complex fracture patterns, e.g., Le Fort fractures 3. Lower face: ~ 25% 1. Mandible
Basic Approach Surgeons perspective: 1. Form: Does the fracture cause a significant cosmetic deformity? 2. Function: Does the fracture pattern disrupts normal function? CT is the imaging standard of reference in evaluating these injuries to determine which patients will require surgical intervention Goal of surgical treatment of displaced craniofacial fractures is to restore preinjury alignment by using rigid fixation
Review of Facial Anatomy To achieve this goal, the facial skeleton is conceptualized as a series of buttresses that supports both form ξ function 4 transverse ξ 4 paired vertical buttresses support facial structures: Transverse buttresses define facial profile/width Vertical buttresses define facial height Transverse Butresses Upper Transverse Maxillary (Orb floor) Lower Transverse Maxillary (Palate) Upper Transverse Mandibular Lower Transverse Mandibular Vertical Butresses Posterior Vertical Posterior Maxillary Pterygomaxillary Lateral Maxillary Lat Orb Wall Medial Maxillary Med Orb Wall
Objectives 1. To review basic anatomy pertinent to maxillofacial trauma 2. To learn major fracture patterns of the midface buttresses 3. The goal is to aid radiologists in accurate fracture description using terms relevant to the surgical management
CT evaluation: Thin-section axial source images in both bone ξ soft tissue algorithm as well as coronal ξ sagittal reformats (particularly useful for fractures oriented in the axial plane 3-D reformats provide a big-picture, overall rendering of facial skeletal alignment which is difficult to appreciate on the axial images Greatly aids surgeons in evaluating cosmetic deformity Soft tissue windows, for signs of injury to the brain or globe
Nasal ξ nasal-septal complex fractures Most common (Approx 50%) CT Checklist! Unilateral or Bilateral? Is it comminuted? Is the septum involved? Is the FP maxilla involved? Any complications: extension into the anterior skull base ξ cribriform plate that may result in anosmia or CSF leak Neuroimag Clin N Am 2010; 20 : 581 596
Nasal ξ nasal-septal complex fractures Radiographic signs of acuity: Overlying soft tissue swelling/ hematoma Opacified sinuses/ hemoantrum Air-fluid levels Physical exam
Isolated Nasal Fracture: Case 1 Bilateral nasal bone fractures Minimal displacement/ no comminution Nasal septal fracture No significant loss of nasal profile or facial deformity
Isolated Nasal Fracture: Case 2 Bilateral comminuted nasal bone fractures Posterior displacement of fracture fragments Comminuted septal fracture Loss of nasal profile with facial deformity
Maxillary Alveolar Fractures Isolated, or part of Le Fort I fracture (sagittal / parasagittal maxillary fracture in high impact injuries) Can devitalize teeth, particularly in children Can result in malocclusion due to widening of the maxillary dental arch Loss of teeth can occur; if all teeth not accounted for Check for aspiration!!
Maxillary Alveolar Fracture: Case 1 Note missing tooth Sagittal, heavily comminuted anterior alveolar fracture Coronal shows degree of comminution Aspirated tooth in lingula
Maxillary Alveolar Fracture: Case 2 Note missing tooth Right parasaggital alveolar fracture extending across midline Additional fractured tooth 3D Recon shows extent of defect ξ Malocclusion
Frontal Sinus Fractures Anterior Table Fractures Constitute approx 1/3 of frontal sinus fractures Anterior ξ Posterior Table Fractures More common approx 2/3 (isolated posterior table fracture is rare, < 1%) Can have associated complications ICH in over 90% of patients with posterior wall fractures (AJNR 1992; 13(3):897-902) Associated CSF leak Pneumocephalus Communication of infection into the dural spaces
Frontal Sinus Fracture: Case 1 89 Y/M in MVC. No neurologic deficits Subdural drain placed, with patient followed to resolution O/E Ecchymosis over Rt eye CT: Open fracture of right frontal sinus involving both anterior ξ posterior tables with Tension Pneumocephalus
Frontal Sinus Fracture: Case 2 Comminuted ξ depressed fracture through the mid frontal sinuses Extends across both anterior ξ posterior tables Intracranial extension demonstrated by pneumocephalus
Mandibular Fractures Ring bone rule: if you see a fracture or dislocation, look for another one Double fractures: usually on contralateral sides of the symphysis. Common combination: angle plus the contralateral body or condyle Triple fractures: fracture of both condyles plus symphysis (guardsman/ or parade ground fracture)
Mandibular Fractures Pretzel-bagel spectrum Condylar neck/ body fractures are most common: Can affect the TMJ Body ξ angle fractures can communicate with a tooth root, causing an open injury Right mandibular angle fracture Complications: Malocclusion Avascular Necrosis with left TMJ subluxation Mandibular growth arrest TMJ ankylosis
Mandibular Fractures: Case 1 6 Y/M fall from bike Right parasymphyseal mandibular fracture Left parasymphyseal mandibular fracture 3-D reconstructions best show malocclusion
Naso-Orbito-Ethmoidal Complex Why Important? The area includes the insertion of the medial canthal tendon(s). NOE fracture refers to injuries involving the area of confluence of the nose, orbit, ethmoids, base of the frontal sinus, ξ the floor of the anterior skull base. Disrupts the confluence of the medial and upper transverse maxillary buttresses
NOE Complex: Imaging Checklist! Radiologic description should include: Single segment versus comminuted fracture at the medial canthal insertion Fracture through nasolacrimal duct Degree of comminution at the FSDP, predisposing to mucocele Affect upon the cribriform plate with possibility of dural injury
Zygomatico-Maxillary Complex (ZMC): The Basics Zygoma, central to normal malar projection, maintains orbital volume, has 4 key articulations 1. Zygomaticomaxillary suture 2. Zygomaticotemporal suture 3. Zygomaticofrontal suture 4. Zygomaticosphenoid suture Displaced ZMC = Tetrapod NOT a Tripod fracture ZT ZF ZS ZM ZMC fracture is a spectrum of injuries, ξ all four fracture components may not be present
Zygomatico-Maxillary Complex (ZMC): The Basics ZMCs, involve 2 buttresses: 1. Upper Transverse Maxillary across the zygomaticomaxillary ξ zygomaticotemporal sutures 2. Lateral Vertical Maxillary across the zygomaticomaxillary ξ zygomaticofrontal sutures
Zygomatico-Maxillary Complex (ZMC): Imaging Checklist! Radiologic Description should include: Degree of zygomatic comminution, displacement ξ angulation Non-comminuted: can remain unfixed Comminuted: need repair Right ZMC fracture traversing the Rt. infraorbital foramen Complications: Damage to V2 Loss of malar/ cheek projection Increased facial width Increased Orbital Volume Comminuted left ZMC fracture with significant loss of left malar projection, restored after ORIF
Zygomatico-Maxillary Complex: Case 1 26 Y/M s/p trauma Surgical correction Comminuted left ZMC fracture with medial displacement ξ lateral angulation at the ZS suture Fracture fragments displace the left LR muscle Results in left proptosis ξ facial widening Open reduction of fracture Plate ξ screw fixation of the ZS, ZM, ZF, ξ ZT sutures Resolution of LR deviation, orbital volume ξ facial width
Orbital Fractures Isolated or occur in association with ZMC, Lefort II/ III, ξ NOE fractures Inferior ξ medial walls are vulnerable Blow-out (fracture fragments extend beyond the orbit) Blow-in (fracture fragments buckle into the orbit
Why Important? Cosmetic complications 1. Enophthalmos: due to a fracture that enlarges the volume of the bony orbit General surgical Rule: Fracture defects >50% of the orbital floor should undergo operative repair because of the high risk of enophthalmos 2. Diplopia: caused by entrapment of an EOM and/or its fascial attachment in the fracture defect
Orbital Fractures Radiologic description should include: Evidence of entrapment of EOMs Entrapment: Clinical, not radiologic, diagnosis IR remains flattened, indicating the fascial support is intact CT signs: 1. Look for evidence of muscle or ST herniation into the fracture defect 2. Check size ξ position of the IR/ MR (and their surrounding fat) 3. Check shape / attenuation characteristics of IR/ MR Note the appearance of IR has changed from ovoid to circular, fascial support is disrupted, ξ the muscle is entrapped
Orbital Fractures: Complications 3 Surgical emergencies 1. Pediatric trap-door fractures flexible bone springs back into place like a trapdoor, looking normal at CT except for the entrapped muscle beneath it 2. Optic nerve injury from fracture affecting the orbital apex 3. Retrobulbar hematoma Prompt communication is critical!! Any radiologic findings of potential damage to the globe or optic nerve, such as a retrobulbar hematoma or an impinging bone fragment, should be immediately communicated to the surgeon Guitar-Pick Sign RadioGraphics 2006; 26:783 793 CJEM 2011;13(3):162-164
Orbital fractures 3 pearls!! 1. Look for other fractures 2. Check for radiological signs that may indicate entrapment 3. Remember 3 surgical emergencies
Le Fort Fractures Le Fort fractures involve a separation of all or a portion of the maxilla from the skull base For this to occur, the pterygomaxillary buttress at the junction of the posterior maxillary sinus with the pterygoid plates must be disrupted Usually B/L ξ symmetrical Malocclusion is a rule
Le Fort Fracture: Simplified Le Fort I Mobilizes inferior maxilla through fractures of all walls of the maxillary sinus ξ nasal septum Floating palate Le Fort I Le Fort II Mobilizes the entire maxilla through fractures through the inferior and medial orbital rims Most common Pyramidal midface fracture causing dish face deformity Le Fort II Le Fort III Craniofacial dissociation with fractures through the zygomatic arch, lateral ξ medial orbital rims Look for associated intracranial injury, injury to the lacrimal apparatus, ξ infraorbital nerve Le Fort III
How to identify a Le Fort fracture? First look at the pterygoid plates If the pterygoid plates are fractured, examine the rest of the facial skeleton for a Le Fort injury
How to identify a Le Fort fracture? Injury Le Fort I Le Fort II Distinguishing Features Clues All walls of maxillary sinus involved Inferior orbital rim involved Best seen in coronal plane Spares medial wall of maxillary sinus, unlike Le Fort I Le Fort III Zygomatic arch involved Distinguish from ZMC by medial orbital ξ pterygoid plate fractures
Case 1: Le Fort I Fracture Mobilizes the inferior maxilla alone due to fractures of all walls of the maxillary sinus, ξ the nasal septum Giving rise to a floating palate
Case 2: Le Fort II ξ III Fractures Le Fort II: Maxillary mobilization Fractures of the: Frontomaxillary ξ Zygmaticomaxillary sutures Le Fort III: Craniofacial dissociation Fractures of the: Zygomaticofrontal Frontomaxillary sutures Zygomatic arch
Summary We have reviewed: Normal facial buttress anatomy Common isolated fractures ξ fracture complexes Selected complications of fractures ξ their repairs, highlighting teaching points that can be used to provide more relevant, valuable information to our surgical colleagues Remember Form ξ Function!