Facial and orbital fractures revisited with MDCT

Facial and orbital fractures revisited with MDCT
Poster No.:
C-2195
Congress:
ECR 2011
Type:
Educational Exhibit
Authors:
R. Ukisu, S. Funaki, K. Matsunari, N. Sunaoshi, M. Tanisaka, K.
Watanabe, K. Koyama, S. Yagi, T. Kushihashi; Yokohama/JP
Keywords:
Head and neck, Emergency, CT, Diagnostic procedure, Computer
Applications-3D, Trauma
DOI:
10.1594/ecr2011/C-2195
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Learning objectives
1) To be familiar with facial and orbital fractures focusing on critical points on MDCT
findings including multiplanar reconstruction (MPR) and three-dimensional: 3D images.
2) To view various pathological condition of facial and orbital trauma.
Background
Facial and orbital fractures can cause a significant cosmetic deformity and/or functional
compromise in any patient. Radiologic evaluation of facial injuries may be difficult due
to the complex anatomy of the region. In contrast, multidetector computed tomography
(MDCT) is useful in the evaluation of facial fractures and has become the gold standard
for diagnostic imaging of facial injuries (Fig. 1).
Images for this section:
Fig. 1: 32-year-old male. Comparison between radiography and MDCT including 3dimensional image. Le Fort I with left ZMC fracture.
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Imaging findings OR Procedure details
Introduction
What do clinicians want to know from the radiologist?
Facial and orbital fractures are as a common consequence of motor vehicle accidents,
assaults, falls, and other blunt trauma. The goal of surgical treatment of displaced
facial fractures is to restore the alignment of the bony fragments by using rigid fixation.
Therefore, the surgical team needs to know the degree and nature of damage to the
facial bone including facial buttresses. Nowadays, MDCT is commonly used to evaluate
patients with blunt facial trauma.
Thus, radiologists have to evaluate imaging findings based on a clinical approach as
well as a neuroradiologic approach. It is essential to envisage what the surgeons want
to know, and give them their answers.
Contents
CT anatomy of facial bone and orbit with schematic drawing
Overview
Cross-sectional imaging
3D imaging
Case presentation
Nasal fx.
Nasal-orbital-ethmoidal: NOE fx.
Zygomatic-maxillary-complex: ZMC fx.
Le Fort fx. (type I-III)
Mandibular fx.
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Orbital fx. (superior, medial, inferior)
Postoperative CT evaluation
Summary
Anatomy of facial bone and orbit with schematic drawing
The facial bones are bones surrounding the mouth and nose and contributing to the eye
sockets (Fig.1).
The facial skeleton can be conceptualized as a series of facial buttresses.
These buttresses represent areas of relative increased bone thickness that support both
the form and function of the face in an optimal relation, and interface with the skull base
or cranium as a stable reference (Fig.2-4).
If facial fracture breaks these buttresses, the surgeon typically treats any significant
buttress displacement using reduction and rigid internal fixation with titanium plates and
screws.
Note. The 3D images are attractive, and most clinicians love them. For the patient, family
education and general education in any respect, they are very visually pleasing (Fig.5).
However, they do not seem to provide complete information for successful surgical
planning.
Why do we do CT in facial trauma?
CT is fast, easy, safe, and widely available. In addition, CT reveals an excellent
delineation of the bones and can detect small fragments.
Multiplanar reconstruction: MPR coronal image with bone window is indispensable to
detect small horizontal fractures, and 3D images sometimes help to evaluate the degree
of deformity (Fig.6).
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There are often other things going wrong in case of facial bone fracture, such as brain
injury; spinal injury; abdominal and/or pelvic injuries. CT is useful to evaluate these
concomitant injuries.
MR is plagued with motion susceptibility and chemical shift artifact. Also, MR is
unavailable in patient who has metallic or ferromagnetic foreign bodies and pacemakers.
Case presentation: CT images including various pearls and pitfalls
Facial fractures are classified as follows:
Nasal fx.
NOE fx.
ZMC fx.
Le Fort fx. (type I-III)
Mandibular fx.
Orbital fx. (superior, medial, inferior)
Postoperative CT evaluation
Nasal fracture
Definition: Disruption of the nasal bone structure, due to trauma.
Clinical findings: Deformity, swelling, epistaxis and periorbital ecchymosis. Bony crepitus
and nasal segment mobility are diagnostic.
CT findings: Fracture, deformity, and distortion of nasal bone. The majority of nasal
fractures involve the thinner, distal third of the nasal bones, and the nasoethmoid margin
remains intact.
Nasal fracture is the most common fracture of the facial skeleton, and usually occurs as
isolated injury. The majority of nasal fracture is caused by lateral blow (Fig. 7-9).
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Approx. 15% of nasal fractures are accompanying with other facial fractures. Severe
nasal fractures can result in superior extension via cribriform plate and orbital roof.
Nasal-orbital-ethmoidal: NOE fracture
Definition: Fracture of the central midface. They must include the bone to which the medial
canthal tendon is attached and may be associated fracture of the frontal, nasal, lacrimal,
ethmoid bones.
Clinical findings: Eye, forehead & nose pain, epistaxis, clear rhinorrhea due to CSF
leakage, epiphora, diplopia, flattened nasal dorsum, exophthalmos, and telecanthus.
CT findings: Comminution of the entire NOE complex may occur. The widening between
the two lacrimal fossae in coronal image (> 35mm). Disruption of the anterior cranial fossa
may be disrupted. The ethmoid complex and nasofrontal recess may result in sinusitis
(Fig.10).
The nasal-orbital-ethmoidal (NOE) complex is the confluence of the frontal sinuses,
ethmoid sinuses, anterior cranial fossa, orbits, frontal bone, and nasal bones. Precise
diagnosis and prompt surgical treatment are essential to avoid complications and to
obtain an aesthetic surgical result.
If the primary struts of the NOE complex are violated, commination of the entire complex
may occur. This may result in telecanthus, enophthalmos, diplopia, and apparent midface
retrusion.
Isolated medial canthal tendon disruption releases the tension on the medial canthus,
causing telecanthus. Disruption of the anterior cranial fossa can result of a CSF fistula,
whereas disruption of the ethmoid sinuses and nasofrontal recess can result of sinusitis.
Zygomatic-maxillary-complex: ZMC fracture
Definition: The zygomaticomaxillary complex (ZMC) plays a basic element in the
structure, function, and aesthetic appearance of the midface. ZMC fracture is any isolated
or combined fracture of the malar eminence and/or zygomatic attachments.
Clinical findings: soft tissue swelling in the area of fracture, diplopia, unilateral epistaxis,
lower eyelid malposition, enophthalmos, telecanthus, trismus
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CT findings: Evaluate the relationship to the temporal bone, maxilla, frontal bone, and
skull base: a quadripod structure. Orbital volume: decreased or increased? Watch the
zygomatic arch. Surgical exposure is indicated if the facture is severely comminuted or
angulated (Fig. 11).
ZMC complex provides normal cheek contour and separates the orbital contents from
the temporal fossa and the maxillary sinus. It also has a role in vision and mastication.
The ZMC provides lateral globe support necessary for double vision, and ZMC patients
can have diplopia by disruption of the lateral canthal ligament.
Successful repair of ZMC fractures requires a accurate diagnosis, prompt surgical
treatment, and reconstituting the complex three-dimensional anatomy.
Other major complications of ZMC fracture are:
1) V3 paresthesia, trismus due to impale the coronoid process of the mandible (15-27%)
and impaled lateral rectus muscle by the displaced lateral wall of orbit.
2) Posttraumatic sinus disease: fractures of sinuses should be evaluated carefully.
3) Intracranial complications.
Le Fort fracture
In 1901, Rene Le Fort classified into three predominant types of midface fracture caused
by blunt forces of various magnitudes and directions (Fig. 12). However, these fractures
rarely occur as defined by Le Fort (Fig. 13-15).
Le Fort fracture type I
Definition: The fracture extends from the nasal septum to the lateral pyriform rims, travels
horizontally above the teeth apices, crosses below the zygomaticomaxillary junction, and
traverses the pterygomaxillary junction to interrupt the pterygoid plates.
Clinical findings: Mobility of teeth, malocclusion and swelling of the upper lip and adjacent
soft tissue with ecchymosis.
Le Fort I fractures (horizontal) may result from a force of injury directed low on the
maxillary alveolar rim in a downward direction.
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Le Fort fracture type II
Definition: A pyramidal, intermediate, horizontal fractures that transverse the orbital floor
and nasal bones.
Clinical findings: Moderate dislocation of midface. Midfacial depression with epiphora.
Telecanthus or CSF leakage on some occasions.
This fracture extends from the nasal bridge at or below the nasofrontal suture through
the frontal processes of the maxilla, inferolaterally through the lacrimal bones and inferior
orbital floor and rim through or near the inferior orbital foramen, and inferiorly through
the anterior wall of the maxillary sinus; it then travels under the zygoma, across the
pterygomaxillary fissure, and through the pterygoid plates.
Le Fort II fractures (pyramidal) may result from a blow to the lower or mid maxilla.
Le Fort fracture type III
Definition: The most superior midface fracture and is characterized as complete
craniofacial disjunction.
Clinical findings: Facial tumefaction, hematoma, bleeding. Neurosurgical injuries, CSF
leakage, significant orbital trauma. Dish face caused by multiple fractures of the
craniofacial dislocation.
These fractures start at the nasofrontal and frontomaxillary sutures and extend posteriorly
along the medial wall of the orbit through the nasolacrimal groove and ethmoid bones.
The thicker sphenoid bone posteriorly usually prevents continuation of the fracture into
the optic canal. Instead, the fracture continues along the floor of the orbit along the inferior
orbital fissure and continues superolaterally through the lateral orbital wall, through the
zygomaticofrontal junction and the zygomatic arch. Intranasal, a branch of the fracture
extends through the base of the perpendicular plate of the ethmoid, through the vomer,
and through the interface of the pterygoid plates to the base of the sphenoid.
Mandibular fracture
Definition: Traumatic break in mandible.
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Clinical findings: Jaw pain. Malocclusion by muscle spasm or hemaethrosis. Trismus
(opening<40mm). Chin anesthesia from mental nerve palsy. Fracture across the mental
foramen can cause severe bleeding and paresthesia.
CT findings:
Fractures tend to follow long axis of teeth. Although the majority of mandibular fractures
do occur at a single site, multiple fractures with/without TMJ dislocations are common
(Fig. 16-18). If TMJ dislocated, empty TMJ sign may be seen on axial CT images.
Blow-out and orbital fracture
Definition: Fracture of orbital floor, usually not an orbital rim; but also of medial or other
orbital walls.
Clinical findings: Diplopia, Enophthalmos, exophthalmos, Periorbital fat and extraocular
muscles can become entrapped in the fracture, leading to problems of ocular movement.
Blow-out fractures are usually caused by a large, low-velocity object. They occur when
the eye is forced back into the orbit, causing the weak floor or medial wall to blow out
into the maxillary sinus or ethmoid sinus. Sports-related injuries are common. When the
medial wall is fractured, the medial rectus muscle becomes entrapped, leading to lateral
gaze dysfunction (Fig. 19).
Medial and superior wall fracture
Medial wall fractures can occur either from direct injuries to the face or indirectly as
blow-out fractures. Orbital emphysema is caused by the communication with the ethmoid
sinuses. Severe orbital emphysema can lead to visual loss from ischemic optic neuritis
and central retinal artery. Superior orbital fracture is a frontal bone fracture that associates
with high-impact injuries to the brain and face (Fig. 20).
Post-operative evaluation
Postoperative CT can assess the adequacy of reconstruction. 3D images can simplify
conceptual understanding of the improvement of skeletal deformity. Axial and coronal CT
reveal the relationship of fixed facial buttresses and titanium plates in detail (Fig. 21).
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Images for this section:
Fig. 1: Anatomy of facial bone and orbit with schematic drawing. The facial bones are
bones surrounding the mouth and nose and contributing to the eye sockets.
Fig. 2: These buttresses represent areas of relative increased bone thickness that
support both the form and function of the face in an optimal relation, and interface with
the skull base or cranium as a stable reference.
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Fig. 3: Coronal CT images (bone window) of facial butresses.
Fig. 4: Axial CT images (bone window) of facial butresses.
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Fig. 5: 3D-CT image of facial buttresses.
Fig. 6: 32-year-old male. Le Fort I with left ZMC fracture.
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Fig. 7: The nasal bones are two small oblong bones, placed side by side at the middle
and upper part of the face.
Fig. 8: Common type of isolated nasal fractures
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Fig. 9: 13-year-old boy. Nasal fracture.
Fig. 10: 10-year-old girl. NOE fracture. On CT, focal midface fracture that separates the
lateral face is seen. T1-W CR image reveals concomitant brain contusion and traumatic
SAH.
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Fig. 11: 37-year-old male. ZMC fracture. Note that the volume of rt. Maxillary sinus is
decreased.
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Fig. 12: Le Fort fracture.
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Fig. 13: 65-year-old male. Le Fort I+III. 3D images reveal outline of fractures nicely,
however, we have all important preoperative information based on facial buttresses
throughout cross-sectional CT evaluation.
Fig. 14: 32-year-old male. Le Fort I fracture with left ZMC fracture. Coronal CT images
show fracture lines, bony fragments, distortion of inner buttresses in detail.
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Fig. 15: 53-year-old male. Right Le Fort I+II fracture, left ZMC fracture and superior orbital
wall fracture…with intracranial complications: AEDH and pneumocephalus. In most case,
you cannot check whole brain images. However, throughout careful evaluation of all CT
images, you can identify some intracranial complication.
Fig. 16: Prevalence of fracture site. Note. Mandiblar fractures may cause airway
obstruction caused by hemorrhage from inferior palantine artery.
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Fig. 17: 23-year-old male. Multiple mandiblar fractures. Although the majority of
mandibular fractures do occur at a single site, multiple fractures with/without TMJ
dislocations are common.
Fig. 18: 34-year-old female. Right condylar neck fracture. In condylar neck fracture,
condylar head pulled medially by lateral pterygoid muscle(*). MDCT provides clear
delineation of the fragment relationships.
Fig. 19: 25-year-old male. Rt. blow-out fracture. Periorbital fat and extraocular muscles
can become entrapped in the fracture, leading to problems of ocular movement. "Blow
out" results in a fracture, though it often prevents globe rupture.
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Fig. 20: Medial wall fractures can occur either from direct injuries to the face or indirectly
as blow-out fractures. The superior orbital wall (also known as the roof) fractures are
usually the result of high-energy injuries.
Fig. 21: Postoperative CT and radiograph (right images) show rigid fixation of six facial
buttresses by titanium plates.
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Conclusion
Nowadays, MDCT is indispensable in helping to evaluate facial trauma. While you
interpreting CT images of a patient with facial and orbital trauma, you should care of all
the facial buttresses. In addition, please remind to ask yourself following five questions.
1) Will this injury cause any physiological malfunction?
2) Will this injury result in a cosmetic deformity?
3) Is there another significant fracture?
4) Is there a foreign body?
5) Is there an intracranial injury?
Thank you for visiting our exhibit.
Images for this section:
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Fig. 1
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Personal Information
R. Ukisu, S. Funaki, K. Matsunari, N. Sunaoshi, M. Tanisaka, K. Watanabe, K. Koyama,
S. Yagi, T. Kushihashi
Department of Radiology, Showa University Northern Yokohama Hospital, 35-1
Chigasaki chuoh, Tsuzuki-ku, Yokohama 224-8503, Japan.
mail to: [email protected]
Images for this section:
Fig. 1: Showa University Northern Yokohama Hospital, Yokohama, Japan
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