Imaging of midfacial and orbital trauma

The midface’s central location, nasal projection anteriorly, and zygomas laterally make it commonly involved in trauma. The midface has singular bony elements including the vomer, ethmoid, sphenoid, mandible and paired bony maxilla, inferior nasal concha, palatine, nasal, lacrimal, and zygomatic bones. The bones form the facial skeleton with four transverse and four paired vertical buttresses. Fractures of the midfacial bones usually involve the nasal bones, followed by zygomatic complex fractures, and often occur from blunt trauma secondary to falls, altercations, or motor vehicle collisions and less commonly in penetrating trauma from gunshots or foreign bodies. Computed tomography (CT) is the imaging modality of choice to delineate fractures and can be used for orbital volumetric measurements and preoperative planning. MRI can be used to supplement CT in assessing intracranial and optic nerve involvement. Although utilized for over a century, the Le Fort classification of midfacial trauma is anachronistic and less relevant for high-speed trauma and does not include orbital and zygomaticofacial complex involvement; therefore, more recent classification schemes may be more relevant for surgical planning. This chapter reviews midface and orbit anatomy, key radiographic features from trauma including the importance of multi-planar imaging, and awareness of critical adjacent structures including the nasolacrimal ducts, orbital musculature, and sinonasal passageways that may be become displaced or obstructed. Importantly, this chapter highlights relevant fracture patterns in midfacial subunits including the nose, naso-orbito-ethmoidal region (NOE), orbital complex, and zygomaticomaxillary complex (ZMC). For each subunit, there is a brief review of relevant epidemiology, clinical features, and critical anatomy affected, highlighting radiographic findings that should be assessed, with a summary of key points, to facilitate optimal treatment.