Published on December 20, 2008
Imaging of Facial Trauma Part 3: Pathology (Nasal, NOE, Frontal, Orbital Fractures) Rathachai Kaewlai, MD www.RadiologyInThai.com Created: January 2007 1
Outline Facial and mandibular fractures Nasal fractures Naso-orbital-ethmoidal fractures Frontal sinus fractures Orbital fractures Zygomatic fractures Maxillary fractures Next presentation Mandibular fractures Imaging approach 2
Nasal Fractures Most common fracture of the facial bone Etiology: motor vehicle collisions (MVC) most common, followed by assaults Relevant anatomy: Nasal pyramid consists of Nasal bones Inferior part of nasal bones is thinner than superior, more prone to fracture (fx) Frontal processes of maxilla Nasal septum (superior = perpendicular plate of ethmoid, inferior = vomer, anterior = quadrangular cartilage) Lateral cartilages (upper and lower lateral cartilages) 3
Nasal Fractures Pattern of nasal fractures depend on direction of force Frontal direction (frontal blow) May cause a simple nasal fx Can be severe with flattening of nose, septum Can be a part of more complicated fx such as naso-orbital-ethmoidal (NOE) fx Lateral direction (lateral blow) May cause depression of ipsilateral nasal bone May also fracture contralateral nasal bone Interlocking of nasal bone and cartilage may occur; requiring open reduction for adequate cosmetic result Inferior direction (blow from below) Usually with septum (quadrilateral cartilage, bony septum) fx and dislocation 4
Nasal Fractures Diagnosis: Made based on physical examination findings Visible bony deformity in displaced fx Laceration, ecchymosis, hematoma, mucosal tear and epistaxis in the inner surface of the nasal cavity strongly suggest fx Presence of epistaxis and septal hematoma requires prompt diagnosis and treatment Epistaxis can be life threatening Septal hematoma may lead to cartilage necrosis and resultant saddle nose deformity Telecanthus is an indication of more severe injury, further workup including CT scan is required 5
Nasal Fractures Plain radiography Plain film may miss up to nearly half of the patients with nasal fractures Nasal bone x-ray: Lateral nasal views (soft tissue technique) Water’s view CT CT better depicts fx, especially frontal process of maxilla. Depressed fx of frontal process of maxilla can lead to facial deformity if left untreated CT should be performed if there is more than a simple nasal fracture on x-ray Presence of telecanthus should prompt CT workup 6
Nasal Fractures, frontal blow 39-yo-man was punched from the front Comminuted bilateral nasal bone fractures (red arrows) with displaced fragments. N = nasal bone M = Frontal process of maxilla Black arrow = Intact nasomaxillary suture 7
Nasal Septum Fractures 33-yo-man was punched by a right- handed person S = Bony nasal septum E = Ethmoid sinus Sp = Sphenoid sinus = Orbital emphysema (in this case from associated maxillary sinus fractures) Fractures of the left frontal process of maxilla (red arrow) and the right nasal bone (green arrow) are noted. A long arrow indicates a fracture of the bony nasal septum. The fractures are displaced to the right, indicating the force of impact from the left. The right-handed person hit the left side of the nose of the victim. 8
Nasal Septum Fractures 67-yo-man involved in a motor vehicle collision S = Bony nasal septum E = Ethmoid sinus Blue arrows = Frontal process of maxilla = Orbital emphysema Deformity of the nose pointing toward the left. There is angulation of the cartilagenous portion of the nasal septum (red arrows) and blood in the nasal cavity. The patient also had orbital floor fractures (not shown) with orbital emphysema (star). 9
Naso-orbital-ethmoidal (NOE) Fractures Etiology: Forceful frontal blow to the central aspect of midface. Most common from motor vehicle collisions (MVC), followed by assaults NOE fractures involve the central upper face, disrupting the medial orbit, nose and ethmoid sinuses NOE fractures are distinguished from simple nasal fractures by Posterior disruption of medial canthal region, ethmoids and medial orbital walls 10
Naso-orbital-ethmoidal (NOE) Fractures Relevant anatomy: NOE complex consists of nasal, frontal, maxillary, ethmoid, lacrimal and sphenoid bones Superior to NOE complex is anterior cranial fossa Lateral to NOE complex is globe Deep to NOE complex is optic canal and sphenoid bone Center of NOE complex is interorbital space, consisting of ethmoid sinuses, lacrimal drainage system, nasofrontal ducts Therefore, NOE fractures can be related to many significant surrounding structures 11
Naso-orbital-ethmoidal (NOE) Fractures Relevant anatomy of Medial canthal tendon A crucial soft tissue component of NOE complex Medial portion of orbicularis oculi, inserting to the medial orbital wall Acts as a suspensory sling for the globe and ensure close apposition of the eyelid In NOE fractures, medial canthal tendon pulls the fragment laterally, or (rarely) torn, causing telecanthus Helpful clinical signs to detect traumatic telecanthus Intercanthal distance > interpalpebral distance of the eyes Intercanthal distance more than one-half of interpupillary distance Clinically, the most obvious deformity is loss of nasal projection in profile and apparent telecanthus 12
Naso-orbital-ethmoidal (NOE) Fractures Pertinent radiologic information Degree of comminution of medial orbital wall, especially in the lacrimal fossa where medial canthus attaches Involvement of nasofrontal ducts require surgical obliteration of frontal sinus to prevent frontal mucocele Extension Posterior extension to the optic canal Superior extension to the frontal sinus, intracranial structures Complications Persistent telecanthus Injury to lacrimal system Nasofrontal duct impingement 13
NOE Fractures 21-yo-man was assaulted E = Ethmoid M = Maxillary sinus Sp = Sphenoid sinus Orbital emphysema = Frontal blow to the nasion results A in a comminuted fracture involving the medial walls of both orbits (green circle), nasal bones (green arrow) and frontal processes of maxillae (red arrows) as shown in image A. Blue arrows indicate the attachment sites for medial canthal tendons. Posterior displacement (depression) of the nasion is noted in image B. B 14
C D 3D images better depict degree of displacement and depression of the NOE fractures. The fractures also extend to frontal sinuses (F). Comminuted fractures of bilateral nasal bones (N) and frontal processes of maxillae (M) are shown. Small images on right lower corners represent normal anatomy in the same projections. Radiologic description should comment on degree of comminution of medial orbital wall especially in the region of lacrimal fossa, where the medial canthus attaches and nasofrontal ducts are located. 15
Frontal Sinus Fractures Etiology: motor vehicle accidents (most common), followed by high-impact sport related injuries Clinical Gross depression or laceration over supraorbital ridge, glabella or lower forehead (most common finding on clinical exam) Ophthalmologic evaluation may be necessary because up to half of patients have orbital trauma Classification of fractures Location: anterior table, posterior table, or both Appearance: linear, comminuted, depressed or nondisplaced Isolated anterior table fracture is most common 16
Frontal Sinus Fractures Relevant anatomy Frontal sinus first appear 6-8yrs, fully pneumatized in adolescence. It can be asymmetric and partially pneumatized in up to 20% of population Frontal sinuses drain via either nasofrontal duct located posteriomedially in the sinus or in conjunction with anterior ethmoid air cells. The nasofrontal duct, if present and fractured, can be obstructed - leading to chronic drainage complication Frontal sinus is closed to dura, frontal lobe, crista galli and cribiform plate 17
Frontal Sinus Fractures Indication for surgery Fracture potentially injures nasofrontal duct (fx involves base of frontal sinus, medial to supraorbital notch) Depressed anterior table - cosmetic deformity Posterior table fx with gross CSF leak, more than one table width displacement Complication Early complication: frontal sinusitis (retained FB in sinus) leading to meningitis, osteomyelitis, orbital abscess or brain abscess Late complication: mucocele, mucopyocele, delayed CSF leak 18
Frontal Sinus Fractures Two examples. Young patients who were assaulted. Above: Isolated anterior table fractures (red arrows) with hemosinus. Intact posterior table (blue arrow). This type of depressed fracture causes cosmetic deformity Below: Both anterior and posterior table fractures (red and green arrows), which are nondepressed. Pneumocephalus (white arrow) 19
Frontal Sinus Fractures Scout CT: Asymmetrical haziness of the left frontal sinus (normal frontal sinus on AP skull radiograph should have same density to the orbit) indicates hemosinus (red arrow). Axial CT: Fracture of the posterior wall of the left frontal sinus (green arrows) is confirmed. There is displacement of the fracture fragments into the sinus. Small pneumocephalus is noted deep to the fracture. The patient also has anterior wall fracture (not shown). Isolated posterior wall fracture is rare. 20
Orbital Fractures Plain radiography has a false negative rate of 7-30% CT in axial, and coronal planes are essential to determine presence of fractures and status of intraocular muscles Axial: medial, lateral wall fracture, entrapment of medial rectus muscle Coronal: floor, roof fracture, entrapment of inferior rectus muscle, fracture involving nasolacrimal duct Both are helpful for fx of optic canal, retro-orbital hematoma Two main types Blow-out fractures Blow-in fractures 21
Orbital Fractures Blowout fractures Bone is displaced away from the orbit May involve the roof, floor, and medial or lateral walls of the orbit Most common = floor If orbital rim is intact = ‘pure’ blow-out fracture (classic fx) Up to 30% have ocular injury Two proposed mechanisms of injury Hydraulic mechanism: pressure on eyeball increases intraorbital pressure, then the orbit ruptures at its weakest point (thin floor) Buckling mechanism: blow to orbital rim results in fx of orbital wall Clinical: Enophthalmos, diplopia and hypoesthesia (infraorbital nerve distribution) can be obscured due to swelling 22
Orbital Fractures Blowout fractures Image interpretation special attention to Appearance of inferior rectus muscle on coronal images Normal = oval shape Abnormal = round shape Location of inferior rectus muscle Abnormal = located below the expected level of orbital floor Abnormal inferior rectus can be Entrapped: muscle lies completely beneath or within the defect and appears round on coronal images Hooked: portion of muscle lies within the defect Entrapment of inferior rectus in children can be easily missed, since flexible bone springs back into place like a trap door, looking normal at CT except for entrapped muscle beneath it This requires urgent Rx within 24-72 hours to minimize motility problem 23
Orbital Blowout Fractures Middle age patient involved in motor vehicle accident Coronal images (in bone and soft tissue windows) shows the defect (red arrow) in the floor of the right orbit with a small hematoma in the right maxillary sinus (green arrow). Light blue arrows point to the inferior rectus muscle, where its inferior portion (blue arrow) is hooked to the defect. O = Optic nerve = Facial soft tissue edema Clinical ophthalmologic exam is required to confirm or rule out evidence of intraocular muscle entrapment. 24
Orbital Blowout Fractures 81-year-old woman fell from stairs Intraorbital fat herniation (green arrow) through the defect in the floor of the left orbit. The inferior rectus (blue arrow) is far from the site of fracture. 3D image shows intact orbital rim (red arrows) indicative of ‘pure’ blow-out fracture. O = Optic nerve, H = Hemosinus 25
Orbital Fractures Blow-in fractures Bone is displaced into the orbit, intraorbital volume is decreased May involve the roof, floor, and medial or lateral walls of the orbit If orbital rim is intact = ‘pure’ blow-in fractures Clinical Exophthalmos (due to decreased orbital volume) Decreased visual acuity (eyeball trauma, optic neuropathy, fracture of optic canal) 26
Orbital Blow-in Fractures 80-year-old man fell onto his face. Fractures of the floor of the left orbit (red arrow) displace superiorly into the orbit. The medial rectus muscle (blue arrows) is pushed upward by the fracture fragment. Intraorbital volume is further decreased by retroorbital hematoma (blue star). H = Hemosinus 27
Orbital Fractures Orbital floor fractures Most common portion of orbit to sustain a fracture Usually associated with other complex midface fractures (ZMC, LeFort II and LeFort III fractures) Can be linear, comminuted, or segmental Herniation of intraorbital contents Best seen in coronal projection What determines chance of herniation, entrapment? Size of fragment, degree of depression Inferior rectus muscle can be free, hooked, or entrapped Indications for surgery Involvement > 50% of the floor, combined floor and medial wall fx with soft tissue herniation, significant enophthalmos (> 2mm), significant diplopia 28
Orbital Fractures Medial wall fractures Usually associated with other complex midface fractures Risk of medial rectus herniation (either hooked or entrapped) - relatively rare Orbital roof fractures Risk of brain herniation into the orbit (better seen with coronal reformatted CT or MRI) Orbital apex fractures Emergent surgical cases if there is radiologic and clinical evidence of optic nerve impingement May be associated with blindness May be associated with carotid artery injury (cavernous portion) 29
Orbital Fractures Soft tissue injuries of the orbit Eyeball rupture Usually there is extrusion of vitreous (normal intraocular pressure is higher than intraorbital pressure) - leading to CT signs ‘flat tire’ sign and ‘deepening’ of anterior chamber Lens injury: subluxation, dislocation, traumatic cataract Zonular fibers hold lens in place to ciliary muscle. If torn (partial or complete), subluxation or dislocation occurs Traumatic cataract (acute lens edema): affected lens has density 30HU less than normal side Intraorbital hemorrhage Intraorbital foreign body 30
Globe Rupture and Vitreous Hemorrhage 21-year-old man was assaulted. Right globe rupture is evident by flattening of the posterior wall of the globe “flat tire sign” (red arrow) and narrowing of the space between cornea and lens “deepening of anterior chamber” (red line). = Vitreous hemorrhage 31
Hemorrhage: Preseptal, Vitreous and Choroidal Preseptal hemorrhage = bleeding in the space anterior to the globe (green arrows, line) Vitreous hemorrhage = bleeding in the posterior chamber of the globe (red star), usually making ‘obtuse’ angle with the surrounding vitreous Choroidal hemorrhage = bleeding in the choroid (white stars) along the wall of the globe Blue arrows represent subcutaneous edema/hemorrhage. 32
Traumatic Lens Dislocation 60-year-old man was found down. Traumatic left lens dislocation (red arrow) is noted. Dislocation occurs due to tear of zonular fibers normally surrounding the lens. Blue arrows point to normal lens with presumed locations of zonular fiber attachment. The patient also has diffuse subarachnoid hemorrhage (red stars) and multiple facial fractures. 33
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. 34
1.Imaging of Facial Trauma Part 3: Pathology (Nasal, NOE, Frontal, Orbital Fractures) Rathachai Kaewlai, MDwww.RadiologyInThai.comCreated: January 20071
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