Frontal Sinus Fractures

Etiology

The most common etiologies of frontal bone fractures in adults are motor vehicle accidents (MVAs), falls, assaults, falling objects, and penetrating trauma.[4] One study of 164 patients reported MVAs as the most common etiology (31.7%) followed by sports accidents (28.0%), work accidents (20.1%), violence (3.7%), and domestic accidents (3.1%).[5] Injury severity is variable and depends on the mechanism, fracture pattern, and involvement of surrounding anatomy. 

In the pediatric community, MVAs were the most common etiology (25.7%), followed by sports-related injuries (16.1%), assault (14.7%), and falls (10.1%). When grouped by age range, the most common mechanism from 0 to 6.99 years old was falls (28.6%), compared with MVAs from 7 to 12.9 years old (31.9), and assaults from 13 to 18 years old.[6]

Epidemiology

Frontal sinus fractures account for approximately 5% to 15% of all facial bone fractures.[4][7][8] These injuries most commonly occur in young males (92%) with a mean age of 20 to 31 years old.[4][9] In pediatric patients, one report noted a male predominance (65%) and a mean age of 11.5 years, with a majority of patients being teenagers.[6] Parietal bone fractures are the most commonly observed skull injuries. Fractures are often linear; however, depressed and basilar patterns can occur. According to Taylor et al., 2.8 million people in the United States suffer from head injuries annually, of which just over 2.1% are fatal.[10]

History and Physical

Obtaining a thorough and comprehensive history is imperative in the initial triage and management of facial trauma patients. Due to the nature of these injuries, patients may not have the capacity to provide this information themselves, making it essential for providers to gather data from family, friends, witnesses, and first responders. 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 for cranial nerve function as well as other focal deficits and bony injury to the calvarium. The physician should inspect the entire head and neck for any lesions, abrasions, contusions, or active bleeding. It is important to assess for lacerations superficial to any sinus fractures, indicating a requirement for IV antibiotics. The anterior table of the frontal sinus should be palpated to determine if there is any bony step-off, and any wounds or lacerations should be cleaned and explored. Examination of the ears can reveal a Battle sign, auricular hematomas, CSF otorrhea, or hemotympanum, suggesting a fracture of the skull base. A nasal examination should check for the mobility of the nasal bones, frank epistaxis, CSF rhinorrhea, septal hematomas, or active purulence. Examination of the orbit should include appropriate cranial nerve testing and inspection for raccoon eyes or retrobulbar hematoma.

Evaluation

After obtaining a comprehensive history and physical exam, the most important test to determine structural involvement and subsequent management is a non-contrast computed tomography scan (CT) of the head and facial bones. Various windows are available through CT imaging (osseous, soft tissue, heme windows), which make the evaluation of these and related injuries rapid and reliable. If CT is available and performed, there is no evidence showing any additional benefit from plain film radiographs. Angiography can be considered if the physician is concerned about possible vascular injury. Ultrasound has the ability to detect fractures with the use of the linear probe in a superficial mode; however, this should be viewed as an adjunct to the previously mentioned modalities.[9][11][12]

Currently, there is no general consensus on the classification of frontal sinus fractures.[4][5][8][13] One-third of all frontal sinus fractures include both the anterior and posterior tables of the frontal sinus, whereas two-thirds involve the anterior table only, and less than 1% involve only the posterior table, as posterior table fractures tend to occur only after force has been transmitted through the anterior table first. Below are some widely accepted classification systems of these fractures:

In 1997, Gonty et al. classified frontal sinus fractures into the following categories. A retrospective review of 158 patients by Gerbino et al. was performed using Gonty’s classification system and reported the percentage of patients with each type of fracture.[4][13][14]

• Anterior table involvement only (61.4%)
• Anterior and posterior table involvement (33%)
• Posterior table involvement only (0.6%)
• “Through and through,” which are defined as comminuted with the involvement of the orbit, ethmoids, and nasal base (2.5%)
• Fractures involving nasofrontal duct (2.5%)

In 2014, Torre et al. presented a classification and treatment schema that is based on maximal metric dislocation and involvement of surrounding structures (nasolacrimal system, orbit, CSF leak, or surrounding bone fracture). In their study of 164 patients, they classified fracture patterns into four types with Type A being most common (38.4%) followed by type D (25%), type B (22.6%), and type C (14%).[5]

• Type A: No displacement
•  Observation
• Type B: 0 to 2 mm displacement
• No concomitant injury - observation
• Concomitant injury - surgical repair
• Type C: 2 to 5 mm displacement
• No concomitant injury - observation
• Concomitant injury - surgical repair
• Type D: greater than 5 mm displacement
• Surgical repair

Treatment / Management

Treatment plans for these patients can vary immensely bared on their related injuries. Nondisplaced anterior table fractures can be monitored with observation and close follow-up. In the case of frontal sinus fracture with an overlying laceration (deemed an open fracture), it is imperative to administer appropriate antibiotics and tetanus prophylaxis/immunoglobulin as indicated. If there is involvement of the anterior table without intracranial communication, IV amoxicillin-sulbactam is sufficient. The addition of a third-generation cephalosporin is appropriate if there is a displaced posterior table fracture. Surgical options, which will be described below, can include frontal sinus ablation/obliteration, closed fracture reductions, cranialization, open reduction with internal fixation (ORIF), and conservative management with observation. As previously mentioned, classification and treatment guidelines are not universal, which could account for variations in patient management; many surgeons have gravitated toward more conservative management in recent years, even electing to observe displaced anterior table fractures, provided no involvement of the frontal outflow tract or posterior table has occurred. In the event that the bone does not remodel on its own, fillers or fat grafts may be placed at a later date in order to improve the cosmesis of the result. Despite this lack of consensus, a posterior table fracture with greater than 5mm of displacement is generally accepted as an absolute surgical indication. Most procedures should take place within 12 to 48 hours from initial presentation, barring any more life-threatening injuries.[4][8][13][15][16][17][18][19](B2)

Observation with Close Follow-Up

• Minimally displaced anterior table fractures (<1-2 mm), without nasofrontal recess injury

Closed Fracture Reductions/Minimally Invasive

• Various minimally invasive techniques exist for the closed repair of anterior table fractures. This type of repair often results in aesthetically favorable outcomes.
• Both percutaneous screws and inflating a Foley catheter within the sinus have been reported as means of fracture reduction.

Open Reduction with Internal Fixation (ORIF)

• This is generally indicated for displaced fractures of the anterior table (>2 mm) without the involvement of the nasofrontal recess or in patients with an obvious cosmetic forehead deformity.
• Surgeons attempting this approach must be able to obtain adequate visualization and access to the sinus to perform the proper repair while considering aesthetic outcomes for the patient. These can be approached either endoscopically or in an open fashion depending on the extent of the fracture and surgeon preference.
• This approach uses small metal plates (microplates) or a titanium mesh and screws to secure the bony fragments. In some cases, reduction screws can be used to support the bone without fixation.

Frontal Sinus Obliteration/Ablation

• This procedure can be indicated in patients who have comminuted anterior table fractures with a linear nondisplaced posterior table fracture or involvement of the frontonasal duct. Another indication is a significant mucosal disruption of the sinus or severely comminuted fractures of the anterior table.
• This entails the removal of all sinus mucosa, occlusion of the nasofrontal duct, and filling the sinus cavity with bone grafts or other materials.  
• Hydroxyapatite, pericranial flap obliteration, adipose tissue, calcium phosphate, and glass ionomer can also be used as grafting material.
• A potential complication of this procedure is a mucocele secondary to incomplete removal of the mucosa during obliteration. If left untreated, mucocele growth can cause further bony destruction.

Cranialization

• This is generally indicated for posterior table fractures with significant displacement or comminution, intracranial injury, or CSF leak. 
• It involves removing the entire frontal sinus contents, including the mucosa, external debris, bone fragmentation, and the posterior table of the frontal sinus. Any anterior table defects must be reconstructed to further protect the brain and dura that have herniated into the frontal sinus.

Differential Diagnosis

• Naso-orbito-ethmoid fracture
• Nasal bone fracture
• Temporal bone fracture
• Parietal bone fracture
• Pott puffy tumor

Prognosis

Prognosis is related to the extent of the injuries sustained as well as the clinical condition of the patient. If there are many injuries, various specialists and subspecialists may be required to treat the patient. Ultimately, isolated frontal sinus fractures have a good prognosis, regardless of whether or not the nasofrontal outflow tract or posterior table is involved. Advancements in surgical technique and equipment have improved the chances of preservation of the frontal sinuses as well as patients’ anticipated quality of life.

Complications

Complications of frontal sinus fractures are typically divided into two categories based on chronicity: acute (less than 6 weeks) or chronic (greater than 6 weeks), but complications overlapping these timeframes may occur. Comlications include but are not limited to:[4][5][11][13]

• Frontal sinusitis
• Meningitis
• Cerebrospinal fluid leak 
• Mucocele
• Mucopyocele
• Osteomyelitis
• Pneumocephalus
• Poor aesthetic outcome
• Brain abscess 
• Chronic frontal headaches
• Extrusion of graft material
• Intracranial hemorrhage
• Diplopia
• Ophthalmoplegia
• Blindness
• Paresthesia of the supraorbital, infraorbital, and/or supratrochlear nerves
• Hypoesthesia or paresthesia of the ophthalmic nerve (V1) or maxillary nerves (V2)
• Facial deformity