Facial Trauma: Frontal Sinus, Maxillary and Mandibular Fractures, Dental Injuries
Benjamin D. Malkin
THE CLINICAL CHALLENGE
Maxillofacial injuries may be blunt or penetrating and may involve soft tissue, bone, and/or neurovascular structures. Knowledge of the underlying anatomy is key in being able to identify which structures have been affected. Careful physical examination, along with appropriate use of imaging, can provide details of the nature and extent of the injury and guide management.
The facial skeleton consists of 14 bones—six paired and two unpaired (Figure 20.1A). They form a system of buttresses that provides support and structure to the face and allows dispersion of oncoming forces away from the cranium. The vertical buttresses consist of paired nasomaxillary, zygomaticomaxillary, and pterygomaxillary midfacial buttresses, and the rami of the mandible. The four horizontal buttresses are the frontal bar, zygoma-inferior orbital rim, hard palate, and mandible.
The 20 primary teeth consist of two types of incisors (four central and four lateral), four canines and two types of molars (four first and four second). The 32 permanent teeth, which begin erupting at age 6 to 7 years, have an additional 8 premolars and 4 third molars (see Chapter 2 for the Universal Numbering System). Each tooth sits in a socket of alveolar bone and receives a neurovascular input at the root.
A 2007 review of 407,167 emergency department (ED) visits for facial fractures found that the most common fracture sites were nasal bones (58.6%), mandible (16.2%), and zygoma/maxilla (13.9%). Twenty-one percent of visits resulted in hospital admission. Males accounted for 68% of cases, and the most common mechanisms of injury were assault (37%), falls (24.6%), and motor vehicle accidents (12.1%).1
APPROACH/THE FOCUSED EXAM
The approach to the patient with facial trauma begins with an assessment for any life-threatening injury. Additionally, owing to relatively high rates of concurrent cervical spine injury, all patients should have their necks immobilized until an injury can be ruled out.
Maxillofacial examination should begin with initial visual inspection to identify any obvious soft tissue injuries, bony deformities, or functional deficits such as cranial nerve weakness. Next, the head and neck should be palpated for step-offs, bony mobility, crepitus, and tenderness. A complete eye exam should be performed (see Chapters 25 and 28). Anterior rhinoscopy can be used to identify sources of epistaxis and septal fractures or hematoma; significant clear rhinorrhea may be an indication of cerebrospinal fluid (CSF) leak. Midface fractures can be assessed by manipulating the central maxillary alveolar ridge while having the other hand on the patient’s nasal bridge or forehead. The extent of the mobile bony segment can suggest one of the three Le Fort fracture patterns. Malar flattening from a zygoma fracture can be assessed by looking from the top of the patient’s head, although this is sometimes obscured by edema. In the presence of prezygomatic soft tissue swelling, the zygomatic arch can be palpated for tenderness through the buccal vestibule.
A careful intraoral exam is essential. Dental evaluation involves examining for missing teeth and occlusal disturbances and evaluating each tooth for injury, mobility, percussion tenderness, and loss of sensation. If a tooth is avulsed and cannot be accounted for, the possibility of aspiration must be considered. Multiple teeth moving together but separate from the adjacent teeth suggests an alveolar fracture. Gingival lacerations, floor of mouth ecchymosis, and displacement of an entire segment are suggestive of a mandibular fracture. It is important to note areas of malocclusion, trismus, and open bite deformities; patients can often report whether their bite feels different from usual and in what way. The tongue blade test is useful in screening for mandibular fractures. While the patient bites down on a tongue blade placed between the molars, the blade is twisted along its long axis. Inability to break the blade is 95% sensitive for mandibular fracture.2
Although conventional X-rays can identify many fractures, computed tomography (CT) imaging is the cornerstone of evaluating facial fractures and is employed as the imaging modality of choice. Axial, coronal, and sagittal cuts should be reviewed to identify the fracture pattern(s). In complicated fractures, three-dimensional (3D) reconstruction can be helpful in visualizing fracture planes and for surgical planning. Cone beam CT is one alternative that can provide favorable bony imaging; soft tissue detail is sacrificed in exchange for a lower dose of radiation. Mandible fractures and dental injuries may also be imaged with panoramic radiographs.
The differential diagnosis of maxillofacial fractures and dental injuries is usually narrowed based on the patient’s physical examination findings and confirmed with subsequent CT imaging. Considerations include whether the injury is limited to the soft tissue or involves the underlying bone, whether the fracture is simple or comminuted, displaced or nondisplaced, open or closed, and whether there is associated nerve or ocular injury. Fractures are usually characterized based on their location and pattern (Figure 20.1B and C). A commonly used scheme includes the following:
Skull base/cranial vault—Frontal sinus, skull base, and cranium.
Midface—Le Fort, zygoma (zygomaticomaxillary complex or isolated arch), orbit, nasal, naso-orbito-ethmoid.
Mandible—Symphysis/parasymphysis, body, angle/ramus, condylar/subcondylar.
Dentoalveolar—Enamel infraction, fracture (crown, crown-root, root, alveolus), concussion, subluxation, luxation (extrusive, lateral, intrusive), avulsion.
Management of facial fractures should be approached in the context of a stepwise trauma protocol, because many result from high-energy mechanisms that can cause associated intracranial, cervical spine, or multisystem injury. Patients can also present with extensive hemorrhage or airway compromise. After life-threatening or potentially disabling injuries have been excluded or stabilized, definitive treatment of fractures can usually be performed electively. Early consultation with a facial trauma specialist (ENT, plastic surgeon, or oral maxillofacial surgeon) is warranted if there are complex, unstable or open fractures, significant trismus, difficulty swallowing, or uncontrolled pain. The focus of definitive treatment is to restore form, function, and stability. Many nondisplaced or minimally displaced fractures do not require operative management. Antibiotics and tetanus vaccine should be considered in the setting of open fractures or dental fractures.