Introduction

Facial trauma is a common reason for patients to visit the emergency department. Midface trauma, in particular, provides a unique challenge for physicians in regards to treatment. Otolaryngologists (ENT) and oral maxillofacial surgeons are commonly consulted for the evaluation of maxillary sinus fractures (MSFs). Knowledge about the diagnosis and treatment of such fractures is very important as it has a large socioeconomic burden on the patient and the healthcare system as a whole. These patients tend to have multiple facial bone fractures, which may require extensive surgery and rehabilitation. Though a maxillary sinus fracture can be used to describe any fracture involving the borders of the maxillary sinus, this paper focuses mostly on anterior and posterior wall maxillary sinus fractures, as other fractures of the midface are out of the scope of this paper.[1][2][3]

Anatomy

In order to understand the diagnosis and treatment of maxillary sinus fractures, it is important to be familiar with the anatomy of the midface. The midface consists of the following facial bones: the maxilla, zygoma, sphenoid, lacrimal, nasal, ethmoid, and palatine.[1] Trauma involving any of these bones should raise concern for the possibility of a maxillary sinus fracture. The pyramidal-shaped maxillary sinus is the first sinus to develop embryologically and is the largest of the paranasal sinuses. The anterior wall is made up of the bony maxilla. Posteriorly, the infratemporal surface of the maxilla makes up the anterior border of the pterygopalatine fossa. The floor of the sinus is made up of the alveolar and palatine processes of the maxilla bone. The zygoma makes up the lateral aspect. The delicate bones of the lateral wall of the nasal cavity make up the medial border. The thin orbital floor, which houses the infraorbital nerve via the infraorbital canal, makes up the superior aspect of the sinus. The blood supply for the maxillary sinus is primarily from branches of the maxillary artery, including the posterior superior alveolar artery, infraorbital artery, and the posterior lateral nasal artery. Innervation of the maxillary sinus and its blanketed mucosa comes primarily from the maxillary division of the trigeminal nerve (V2).[4]

Etiology

Maxillary sinus fractures are most commonly caused by blunt force trauma to the face. The mechanism of injury varies based on the age of the patient, the external force vector, and anatomic location.[3] Trauma can come from motor vehicle accidents (MVA’s), domestic disputes, falls, industrial accidents, or assaults with or without a weapon.[2][5][6][7][8] Injuries to the lateral midface (63%) are more common than to the anterior midface.[1] Of note, approximately 5% of mandibular fractures induce isolated posterior and lateral maxillary sinus fractures.[2] Also, in MSFs, 43% of patients have concomitant cranial nerve injuries, with the infraorbital nerve being most commonly involved, followed by the facial nerve.[1]

Epidemiology

It is difficult to accurately estimate the prevalence of MSFs due to the number of maxillofacial bones that make up and surround the maxillary sinus. Many of these patients have multiple affected bones, and fractures of any of these bones may affect the maxillary sinus. Patients with facial bone fractures are most commonly males with an average age range of 21 to 30 years of age.[3][5][7] The nasal bone is the most common bone to be fractured but does not usually require surgery. The mandible is the most common maxillofacial bone to fracture requiring surgery and occurs in a reported 38 to 63% of their cases.[2][3][5] Though the mandible does not directly make up the maxillary sinus walls, one study found that mandible fractures were associated with posterior maxillary sinus fractures in up to 11% of cases.[5] The second and third most common fractured maxillofacial bones are the maxilla and the orbit (39.8%), both of which make up the walls of the maxillary sinus.[5][9]

History and Physical

It is important to obtain information regarding the age of the patient, mechanism of injury, and age of the injury. Since many of these patients will have injuries as a result of the trauma, they may be intubated and unable to answer questions. It is critical to utilize the information provided by first responders, family, friends, witnesses, and emergency room practitioners when making clinical decisions in this patient population.[7] Physical examination may also be difficult for a variety of reasons ranging from significant facial swelling to patient sedation or intubation. Drugs and alcohol are also frequently associated with these injuries making physical examination even more difficult.[5]

Per the Advanced Trauma Life Support (ATLS) protocol, the evaluation of trauma patients begins with an assessment of the patient's airway, respiratory capacity, and circulatory status. While assessing the extent of the patient's disabilities, a thorough neurologic exam should be performed to calculate a Glasgow Coma Scale Score, assessing cranial nerve function, and inspecting for focal deficits or bony injury to the calvarium. After ensuring patient stability and obtaining a patient history, it is important to perform a full head and neck examination. The exact order of this exam will vary from practitioner to practitioner. However, every exam should be performed in the same order to ensure nothing is missed. The provider should inspect the entire head and neck for any lesions, abrasions, contusions, or active bleeding. Since many MSFs are associated with multiple maxillofacial bone fractures, one of the most important roles of this secondary survey is to look for injuries not noticed on the primary survey. Practitioners should pay attention to obvious deformities, most commonly involving the nose, zygomatic arch, and mandible.[7] Bleeding from lacerations should be controlled, and the wounds should be irrigated, explored, and closed if possible. The facial bones should be palpated to evaluate bony step-offs or instability. A complete oral examination should be performed as there may be protrusion of the bony maxilla or mandible through the mucosa and into the oral cavity. Also, look for any loose teeth or changes in occlusion, which can be the only indication of a mandible fracture.[7] Though nasal examination may be limited, it is important to examine for cerebrospinal fluid (CSF) leaks, septal hematomas, epistaxis, or purulent drainage. Examination of the ears can reveal Battle's sign, auricular hematomas, CSF otorrhea, or hemotympanum, suggesting further fracture involvement of the skull base.[8][10]

The neurologic examination is an integral component of the physical exam in these patients as nerve entrapment is an indication for surgical correction. Measuring and comparing pupil diameter with reactivity to light can help diagnose cranial nerve injury. If the patient is awake and cooperative, a thorough ocular exam should be performed, including extraocular motion testing, tonometer testing, and the Snellen chart vision test. If the patient is unable to cooperate with examination, it is important to test forced duction of the eye, which may reveal entrapment of the extraocular muscles. Be aware of possible corneal abrasions, which can be viewed on slit-lamp evaluation, or the presence of raccoon eyes suggesting further basilar skull damage. Facial nerve testing should be performed if there is concern about paralysis or paresis, as this may indicate the need for urgent surgical intervention.[1][5][6]

Evaluation

Though physical examination may be enough to diagnose obvious MSFs, many times, concurrent imaging will be needed to exclude other injuries and assist with presurgical planning. Computed tomography (CT) of the maxillofacial bones without contrast is the gold standard imaging study needed in facial trauma patients.[5][10][11] Computed tomography will reveal cortical fractures and show the amount of bony displacement, which will help to dictate further management. This can also help identify other local associated fractures, which will help dictate further consults, treatment plans, and prognosis.[11] CT scans are also excellent for identifying foreign bodies, local hemorrhage, and some soft tissue injuries. With the advent of three-dimensional CT (3D-CT), physicians are even better apt to understand the complex nature of these fractures and their segments. But due to the excellent bony visualization, lower cost, and lower radiation of two-dimensional CT’s, current recommendations for 3D-CT scans are limited to severe facial polytrauma and both preoperative and postoperative imaging.

Less commonly used imaging modalities, including magnetic resonance imaging (MRI), plain film x-ray, and ultrasound, which have limited utility compared to non-contrast CT.[11] With that in mind, MRIs tend to be indicated as a complement to initial CT scans, specifically with suspected CSF leaks and orbital soft tissue injuries.[5] MRIs are also better able to detect and differentiate a herniation of orbital fat versus entrapment of orbital muscle. Ultrasound imaging has been used with some success for superficial fracture diagnosis in the orbit, specifically with the zygomatic arch and nasal bones. Unfortunately, it has limited clinical utility in diagnosing nondisplaced fractures of the maxillofacial bones and has poor penetration limiting views of the orbital floor.

Treatment / Management

With maxillofacial trauma, specifically MSFs, the most important treatment step is to stabilize the patient via the ACLS algorithm. Patients must have an established airway, control of bleeding, and cardiovascular stability before addressing maxillary sinus fractures. This may include a prophylactic tracheostomy to ensure a secure airway.[12] In most cases, maxillofacial fractures are non-emergent and can be treated up to two weeks following the initial trauma; however, most will likely require hospitalization.[1][10][12] These injuries are generally associated with LeFort fractures and should be treated accordingly.[8] Management of maxillary sinus fractures is controversial but can be split into surgical vs. conservative management.[6][9]

Advocates for conservative treatments usually cite the mortality and morbidity of surgery as a reason to avoid the operating room. They note the limited comorbidities associated with damage to most isolated anterior wall MSFs, and surgical reconstruction has been thought to possess more risks than benefits. ORIF has been correlated with facial swelling, the creation of additional bony fragments, paresthesia, gingival numbness, hardware migration, postoperative pain, and wound infection.[13] Historically, conservative management generally meant antibiotics to prevent sinusitis, steroid use to reduce local inflammation and close follow up. Antibiotic prophylaxis is still somewhat controversial.[1][2] One single-institution study of 50 patients with nonoperative maxillary sinus fractures compared the rates of acute maxillary sinusitis between a control group (nasal saline) and a treatment group (antibiotics). They found that 95% of the patients in the antibiotic group and 88% in the control group had symptoms of maxillary sinusitis three days after injury and concluded that a 3-day course of antibiotics is not effective in preventing infection.[14] In 2016, Malekpour and colleagues compared the incidence of soft tissue infections in nonoperative facial fracture patients. They found no difference between patients without antibiotic prophylaxis and patients with either short or long-term antibiotic prophylaxis.[15] Close clinical follow-up on these patients is essential as some symptoms may be delayed in their presentation. CSF leaks may be delayed until the edema of the surrounding tissues begins to decrease.[1]

Surgical indications for MSFs are similar to the indications for LeFort fractures, which include poor facial aesthetics, restoration of midfacial height, correction of malocclusion, and repair of midface projection.[6][9][12] If surgical indications are met, basic treatment of the anterior sinus wall should be based on repositioning the fracture segments with fixation using plates, screws, mesh grafts, or resorbable foils. Most surgeons will plan for open reduction and internal fixation (ORIF) via a Caldwell-Luc (gingival buccal) incision or an endoscopic nasal approach depending on the provider's preference. Recently, there have been new techniques that have been described in the literature. However, no one approach has been proven superior.[13][16] In 2017, three separate groups reported using urinary balloon catheters and/or fibrin glue to reposition bony fragments in isolated anterior wall sinus fractures.[9][13] Kim and colleagues noted acceptable results without complications using two urinary catheter balloons with fibrin glue to hold fractured segments together.[13] Yang and colleagues described a new procedure to help reduce anterior wall fractures, lateral wall fractures, or even zygomatic tripod fractures after facial trauma. The group described the "transnasal endoscopic-assisted ultrasound-guided intranasal reduction of maxillary sinus wall (TERM), which uses a foley catheter balloon to reposition bony fragments of maxillary sinus wall fractures under external ultrasound guidance after maxillary antrostomy.[9]

Differential Diagnosis

• Zygomatic arch fracture
• Mandible fracture
• Inferior orbital rim fracture
• Orbital floor fracture
• Nasal bone fracture
• Nasoorbitoethmoid fracture
• Acute, chronic, or recurrent maxillary rhinosinusitis
• Facial hematoma or contusion

Prognosis

The prognosis of these patients is largely based on the severity of the injuries. Since many patients with maxillary sinus fractures will also have multiple other injuries, it is difficult to predict outcomes. Some negative prognostic indicators include anosmia, complete vision loss, severe fracture displacement, and late intervention; however, patients with these symptoms likely have more severe injuries than an isolated maxillary sinus fracture.[1] The most common long-term complication is dental malocclusion or malunion of the fracture site.[7]

Complications

Noted complications in the literature include:[1][6][7][8][17]

• Extraocular eye muscle entrapment (inferior rectus and inferior oblique muscles)
• Orbital cellulitis
• Orbital abscess
• Orbital emphysema
• Enophthalmos
• Hypophthalmos
• Maxillary sinusitis
• Maxillary sinus mucocele 
• Epistaxis
• CSF rhinorrhea
• Oromaxillary fistula
• Dental malocclusion
• Facial asymmetry
• Aesthetic concerns
• Pressure sensitivity
• Chronic facial pain
• Infraorbital nerve paresthesia

Consultations

Consultations vary depending on the involvement of maxilla and its surrounding structures:[10]

• Ophthalmology
• Otolaryngology
• Rhinology 
• Facial plastic surgery
• Trauma surgery
• Oral maxillofacial surgery (OMFS)
• Neurosurgery

Deterrence and Patient Education

Maxillary sinus fractures are generally caused by unpredictable trauma, so it is hard to say how we can deter these situations. The following are recommend safety precautions with vehicles and other machinery, which can help to reduce the severity of these injuries. Other authors note that using the following would decrease the number of motor vehicle collisions, thus reducing the most common etiology of these injuries: traffic cameras, improved road design, speed bumps, or safer pedestrian routes. Using proper sport-related protective equipment can reduce sports-related injuries. Avoiding precarious situations or locations can help to prevent assaults or falls.[3]

Pearls and Other Issues

• The maxillary sinus is one of the most common midface fracture sites reported in the literature.
• Maxillary sinus fractures are most commonly due to trauma from MVA's, falls, domestic disputes, accidents, or assaults.
• Patient stabilization with the ACLS protocol should be the first step in the management of these fractures. A thorough head and neck examination with neurologic evaluation is necessary to look for associated injuries and prevent complications.
• Noncontrast computed tomography scan of the maxillofacial bones is the gold standard imaging modality for these patients. Plain film x-rays, ultrasound, and MRI have less clinical utility in these patients.
• Physicians can wait up to two weeks to repair maxillary sinus fractures, allowing time to manage more life-threatening injuries.
• Isolated maxillary sinus fractures are typically treated with conservative management.
• Prophylactic antibiotic use for isolated MSFs is still controversial in the literature.

Enhancing Healthcare Team Outcomes

The treatment of maxillary sinus fractures can require an interprofessional team, depending on the extent of the injury. The emergency response team and emergency department members will be necessary to identify any life-threatening injuries and stabilize the patient upon presentation. Surgical reconstruction may need to be carried out by the proper surgical teams, which could vary depending on any associated injuries and surgeon availability. One or multiple board-certified surgeons may be needed to treat these patients, which could include an otolaryngologist, facial trauma surgeon, oral maxillofacial surgeon, facial plastic surgeon, neurosurgeon, and/or ophthalmologist. The operating room (OR) staff, including surgical technicians and circulating nurses, will be imperative to keep the OR moving smoothly and improve surgical outcomes. An intensive care unit or critical care team made up of physicians, mid-level providers, nurses, and other staff may be needed to manage the patient medically, either pre- or postoperatively. Since these patients may be hospitalized for an extended amount of time, it is important for physical, occupational, and speech therapists to be involved in their care to improve long-term outcomes.