The Imaging of Maxillofacial Trauma and its Pertinence to Surgical Intervention Nisha Mehta, MDa, Parag Butala, MDb, Mark P. Bernstein, MDa,* KEYWORDS Maxillofacial trauma Surgery Imaging Maxillofacial skeletal injuries account for a large positioning is difficult and potentially dangerous proportion of emergency department visits and for multitrauma patients, in particular patients often result in surgical consultation.1 Although requiring cervical spine clearance. Modern multi- many of the principles of detection and repair are detector CT (MDCT) scanners have revolutionized basic, evolving technology and novel therapeutic trauma imaging and provide a fast, safe, cost- strategies have led to improved patient outcomes. effective, and sensitive means for assessing The goal of imaging studies in the trauma setting is trauma for bone and soft tissue injuries. Further- to define the number and location of facial fractures, more, with the advent of MDCT, facial scans with particular attention toward identifying injuries to can now be performed contemporaneously with functional portions of the face and those with head, thoracic, and abdominal scans, facilitating cosmetic consequence. By understanding common a rapid assessment for trauma patients with fracture patterns and the implications for clinical multiple potential injuries. management, radiologists can better construct clin- MDCT offers excellent spatial resolution, which ically relevant radiology reports and thus facilitate in turn enables exquisite multiplanar reformations, improved communication with referring clinicians. and 3-D reconstructions, allowing enhanced diag- This article aims to provide a review of the imaging nostic accuracy and surgical planning. These aspects involved in maxillofacial trauma and to reconstructions assist in the assessment of frac- delineate its relevance to management. ture fragment displacement and rotation as well as identification of fracture patterns. For these TECHNOLOGY reasons, MDCT is the imaging technique of choice in maxillofacial trauma. Imaging in most emergency departments for Although 2-D transaxial and coronal images are significant facial trauma begins with CT scanning. more accurate and sensitive than 3-D reconstruc- Although plain radiographs were once standard tions, 3-D imaging is often preferred by surgeons imaging, they do not provide sufficient information because it simulates a surgeon’s process of visu- to assess injury severity and displacement, two alizing fractures in operative planning. Nonethe- key aspects essential for emergent management less, it is important to recognize limitations in 3-D and surgical planning. In addition, radiographic imaging, namely the introduction of artifact during The authors have no financial support or interests to disclose. a Department of Radiology, NYU Langone Medical Center/Bellevue Hospital and Trauma Center, 550 First Avenue, New York, NY 10016, USA b Institute of Reconstructive Plastic Surgery, NYU Langone Medical Center, 550 First Avenue, TCH-169, New York, NY 10016, USA * Corresponding author. E-mail address: [email protected] Radiol Clin N Am 50 (2012) 43–57 doi:10.1016/j.rcl.2011.08.005 0033-8389/12/$ – see front matter Ó 2012 Elsevier Inc. All rights reserved. radiologic.theclinics.com 44 Mehta et al the reformation process, decreased ability to visu- reformations and 3-D reconstructions are gener- alize nondisplaced fractures, the lack of adequate ated according to the area of interest on a case- soft tissue evaluation, and difficulty viewing deep by-case basis. fractures on surface views.2 MR imaging may occasionally be used to eval- At the Bellevue Hospital and Trauma Center uate soft tissue injury with the advantage of avoid- currently scans are from the frontal sinus ing ionizing radiation while providing excellent soft through the hyoid bone to include both the tissue contrast. MR imaging is particularly helpful mandible and the facial bones. Scanning is in assessing cranial nerve deficits. Although MR acquired at submillimeter thickness with overlap imaging also offers multiplanar capabilities, it is (0.625 mm  0.4 mm) to generate high-quality limited in its ability to assess cortical bone and is multiplanar reformations and 3-D reconstruc- often not a feasible modality secondary to acces- tions. CT images are reviewed at 2-mm thick sibility and availability. In addition, it is usually reformations oriented parallel and perpendicular impractical in the trauma setting due to the need to the hard palate to achieve symmetry in both to rule out life-threatening injuries promptly and the transverse and coronal planes. Sagittal patient inability to remain still during the lengthy images are also generated for review. All images examination. Most importantly, metallic fragments are processed using bone and soft tissue algo- must be excluded before imaging with MR rithms (Fig. 1). Additional oblique or curved imaging. Fig. 1. A 22-year-old man, assaulted, with facial pain. (A) CT scout view shows scan range from top of the frontal sinus to the bottom of the hyoid to include the entire facial skeleton, including the mandible. Transaxial images in bone (B) and soft tissue (C) demonstrate a left lateral orbital wall fracture (white arrow) with left periorbital swelling. The globes and lenses are intact. Retrobulbar soft tissues are normal. (D) Coronal reformation reveals fractures of the left zygomaticofrontal suture (short white arrow), left orbital floor (long white arrow), and left zygomaticomaxillary suture (black arrow). Together, with zygomatic arch fracture (not shown), this injury pattern is a ZMC fracture. (E) Oblique sagittal reformation along the plane of the left optic nerve shows the orbital floor fracture to better advantage giving the surgeon an improved understanding of the size and depth of the defect. The optic nerve and superior and inferior rectus muscles are well displayed on this projection. (F) 3-D reconstruction in a Water’s projection shows the overall ZMC fracture pattern (arrowheads) in a single image and aids in surgical planning. The Imaging of Maxillofacial Trauma 45 NASAL FRACTURES deviation, and septal and soft tissue injury Anatomy (Fig. 2). Generally, nasal trauma with septal frac- ture or dislocation causing severe alteration of The nasal region consists of bony and cartilaginous the nasal midline or with severe soft tissue injury portions. Whereas the anterior nasal septum is requires an open repair, whereas most others cartilaginous, the remainder of the nasal septum, can be treated with closed reduction.4 consisting of the posterior perpendicular plate of the ethmoid, vomer, nasal crest of the maxilla, and NASO-ORBITAL-ETHMOID FRACTURES nasal crest of the palatine bone, is bony. The upper Anatomy third of the nasal region (consisting of the nasal bones proper, the frontal process of the maxilla, The interorbital space is referred to as the naso- and the nasal process of the frontal bone) is bony, orbital-ethmoid (NOE) region; it represents the whereas the middle and lower thirds of the nasal bony confluence of the nose, orbit, maxilla, and region (composed of the upper lateral and lower cranium. The space is defined by the thin medial alar cartilages, respectively) are cartilaginous. orbital walls laterally, the sphenoid sinus posteri- orly, the cribriform plate superiorly, and the bony Injuries pillar (the frontal process of the maxilla, nasal process of the frontal bone, and the thick proximal The nose is the most prominent facial projection. nasal bones) anteriorly. Several key structures lie Consequently, nasal bone fractures account for within this region, including the olfactory nerves, approximately 50% of all facial fractures, with the the lacrimal sac, the nasolacrimal duct, the majority involving the distal third of the nose.3 ethmoid vessels, and the medial canthal tendon. Because the diagnosis is usually made clinically and radiologic evaluation is usually unnecessary, Injuries there is limited role for dedicated imaging. Radi- ology reports from head CT scans or imaging Once an anteriorly directed force is sufficient to directed at detecting other facial fractures, how- fracture the nasal bones, the posterior ethmoid ever, often bring a nasal bone fracture to the atten- air cells offer little resistance and are easily frac- tion of the emergency department staff and tured with impaction and resultant telescoping. facilitate further evaluation, which can prevent clin- The fracture pattern then progresses from simple ical complications, such as a cosmetic deformity or nasal fracture into the NOE type, which addition- a septal hematoma resulting in saddle nose defor- ally involves the medial orbit, septum, and naso- mity. In these cases, early reduction prevents bony frontal junction. This pattern is most often seen in malunion, thus avoiding the need for osteotomy to blunt trauma directed at the nasal bridge. anatomically reduce fracture fragments. CT is essential to identifying the location of the Several classification systems exist for nasal injury, pattern type, degree of comminution and and septal fractures, grouping fractures according displacement, and associated fractures and soft to whether fractures are unilateral or bilateral, tissue injury. CT typically demonstrates blood in degree of displacement, comminution, midline the ethmoid air cells and impacted fractures in Fig. 2. Nasal fractures. (A) Transaxial and (B) coronal CT reformations of a 25-year-old male victim of assault shows bilateral comminuted