Frontal Sinus Fractures

Frequency

Frontal sinus (FS) fractures account for 5-12% of all facial fractures. A multicenter study from Italy, by Salzano et al, suggested that the coronavirus disease 2019 (COVID-19) pandemic significantly affected the epidemiology and etiology of facial traumas. With regard to fracture sites, the prevalence of FS fractures between February 23 and May 23, 2019 and 2020 was 0.9% and 4.4%, respectively.[3]

Motor vehicle accidents account for 71% of frontal sinus (FS) fractures, assaults account for 10%, industrial accidents account for 5%, recreational accidents account for 4%, and other causes (eg, gunshot) account for 6%.

In a retrospective study of pediatric facial fractures seen at an urban level 1 trauma center, Oleck et al reported that frontal sinus fractures were more frequently the product of falls than of other causes of injury.[4]

Isolated anterior table fractures account for 33-39% of frontal sinus (FS) fractures. Combined fractures of the anterior table, posterior table, and/or nasofrontal recess (NFR), also termed the nasofrontal outflow tract, appear in 55-67% of cases. Isolated posterior table injuries are rare (< 6%), but the status of the displacement of the fractures and the patency of the nasofrontal recess must still be accessed.[5]

As many as 33% of patients have an associated cerebrospinal fluid (CSF) leak.

Patients with frontal sinus (FS) fractures often have associated facial injuries or panfacial fractures. A thorough head and neck examination is imperative.

• Symptoms of FS fractures include the following:

  • Forehead swelling

  • Forehead and nasal pain

  • Forehead paraesthesias

• Signs of nasoorbitoethmoid (NOE) fractures include the following:

  • Forehead lacerations

  • Forehead tenderness

  • Concave frontal bone contour

  • Cerebrospinal fluid (CSF) rhinorrhea (see Lab Studies)

• Perform an initial evaluation, as follows:

  • Assess airway, breathing, and circulation (ABCs).

  • Diagnose any associated injuries.

  • After the patient is stabilized, perform a thorough head and neck examination to evaluate injuries to the brain, spine, and orbits.

    • Serious injuries are associated with FS fractures in 75% of patients. Associated facial fractures are present in 66% of patients, initial loss of consciousness occurs in 76% of patients, and prolonged periods of unconsciousness occur in 23% of patients.

    • A team approach involving the otolaryngologist or plastic surgeon, neurosurgeon, and ophthalmologist is recommended. Consultation with an ophthalmologist is mandatory.

• Conduct directed examination of the FS, as follows:

  • Displaced fractures of the anterior table without overlying lacerations may not be apparent on physical examination because of soft tissue swelling or hematoma.

  • All forehead lacerations should be examined under sterile conditions to assess the integrity of the anterior table, posterior table, and dura.

  • Clean and examine the nasal cavity for the presence of a CSF leak. Query all conscious patients about the presence of watery rhinorrhea or salty postnasal drainage.

  • Palpate the nasal bones for crepitus and comminution.

  • Evaluate the integrity of the medial canthal tendon (MCT) by placing the thumb and index finger over the nasal root and carefully applying lateral tension to each lower lid. Normally, a defined end point to the maneuver is evident without palpable motion at the medial orbital rim. A lax MCT or medial orbital wall motion is consistent with an NOE complex fracture.

Development

The frontal sinus (FS) is absent at birth. The anterior ethmoid cells invade the frontal bone at 2 years of age, and the FS attains adult size at approximately 15 years of age. The image below is a diagram of frontal sinus development.

The FS measures 30 mm tall, 25 mm wide, and 19 mm deep in the average adult, demonstrated in the image below. Average FS volume is 10 cm3.

The FS is most commonly bilateral, asymmetric, and pyramidal in shape.

• The pyramidal base is located inferiorly, and the apex is located superiorly. The floor of the sinus forms the medial portion of the orbital roof.

• The FS usually is divided by one or more intersinus separations. A unilateral, rudimentary, or absent FS is present in 20% of individuals.

Anterior table

The anterior table forms part of the forehead, brow, and glabella. It averages 4 mm in thickness but can be as thick as 12 mm. The anterior table is more resistant to fracture than any other facial bone.

Posterior table

The posterior table abuts the anterior cranial fossa. The thickness of the posterior table ranges from 0.1-4.8 mm, and it is much less resistant to injury than the anterior table.

Frontal sinus ostia

The FS has 2 ostia located on the posterior inferior aspect of the sinus floor. They are positioned anterior to the anterior ethmoid air cells, medial to the orbit, lateral to the intersinus septum, and posterior to the frontal bone.

Each ostium is approximately 3-4 mm in diameter and represents the sole drainage site for the FS.

The true ostium is the narrowest point of an hourglass configuration. The FS infundibulum is located cephalad to the ostia (the upper part of the hourglass) and narrows down to the true ostia. The NFR widens out below the ostia (the lower part of the hourglass) and enters into the ethmoid infundibulum.

The NFR is extremely short in 85% of individuals and, thus, is more accurately described as a recess rather than a true duct.

Neurovascular supply

The supraorbital and supratrochlear vessels provide arterial supply to the FS. Venous drainage occurs through 3 pathways: the facial vein, the ophthalmic vein/cavernous sinus, and the foramina of Breschet/subarachnoid space.

Sensory innervation of the FS comes from the ophthalmic branch of the trigeminal nerve.

Beta-2 transferrin test

The beta-2 transferrin test is the definitive means of evaluation for CSF rhinorrhea. One milliliter of the suspected fluid should be collected in a red-top tube. The beta-2 transferrin test is a "send-out" laboratory test at most institutions.

Watery rhinorrhea positive for beta-2 transferrin is diagnostic of a CSF leak. Besides CSF, only the vitreous humor of the eye and the perilymph of the ear have been found to contain beta-2 transferrin.

Halo sign test

Bloody rhinorrhea suspicious for CSF can be placed on filter paper and observed for a halo sign. If CSF is present, it diffuses faster than blood and results in a clear halo around the central stain.

Other

Routine chemistry analysis of the rhinorrhea may reveal an elevated glucose content consistent with CSF.

Plain sinus radiographs may reveal FS opacification or gross bony step-offs.

Thin-cut axial and coronal CT scans (1.5 mm) are the criterion standards for the evaluation of FS fractures. However, the compact anatomy of the NFR can make accurate fracture diagnosis in this area difficult. Axial images reveal the location, severity, and degree of comminution of anterior and posterior table fractures. Coronal images reveal fractures of the FS floor and orbital roof.

See the image below.

The most appropriate treatment of frontal sinus (FS) fractures can be complex and, at times, controversial. The treating physician should have a clear algorithm in mind for management of different fracture patterns.

The author proposes a conservative algorithm for the treatment of most FS injuries. Treatment options include observation, open reduction and internal fixation (ORIF), sinus obliteration, sinus exenteration (ie, removal of anterior table, Reidel procedure), and sinus cranialization. The algorithm is based on 5 anatomic parameters that need to be evaluated before deciding on the most appropriate treatment option. These parameters include NFR fractures, anterior table fractures, posterior table fractures, dural tears (CSF leak), and degree of fracture comminution. Fascial planes of the forehead and temple are depicted below.

Nondisplaced or minimally displaced (< 1-2 mm) isolated anterior table fractures can be managed conservatively with local wound care and analgesics. Patients should be closely observed for signs of frontal sinusitis, which may indicate fracture involvement in the nasofrontal duct.

A study by Dennis et al indicated that nonsurgical treatment is a viable means of addressing nonobstructed fractures of the FS ostium or NFR. The reaeration rates of the study cohort’s sinuses following conservative management of such injuries were 91% (ostia) and 98% (NFRs). For obstructed fracture patterns, the reaeration rates were 50% and 77%, respectively.[6]

General goals of surgical therapy include protection of intracranial contents, prevention of early and late complications (eg, meningitis, mucocele), restoration of aesthetic forehead contour, and return of normal frontal sinus (FS) function. Although accomplishing all these goals may not be possible, the intracranial contents must be protected, and a "safe" sinus must be reconstructed. Repair of aesthetic and functional deformities can be addressed secondarily.[7, 8, 9]

A study by Choi et al in which the investigators surveyed facial plastic surgeons with otolaryngology training, general otolaryngologists, plastic surgeons, and oral and maxillofacial surgeons found that 61.7% of respondents believed that endoscopic sinus surgery had altered their way of managing frontal sinus fractures. The study also found that when it came to uncomplicated, nondisplaced frontal sinus outflow tract fractures, 91.8% of the physicians surveyed favored observation. In terms of uncomplicated, displaced frontal sinus outflow tract fractures, 36.4% of respondents favored observation and 35.9% favored endoscopic sinus surgery. Plastic surgeons and oral and maxillofacial surgeons had a greater tendency to favor obliteration in complicated, displaced frontal sinus outflow tract fractures than did the physicians with otolaryngology training.[10]

A review by Dedhia et al of current trends and literature in the management of frontal sinus fractures remarks on the evolving conservative management of select cases and the expansion of such treatment due to the role of minimally invasive endoscopic sinus surgery techniques. The authors outline a new algorithm for treatment decisions and emphasize the need for follow-up of at least a year to monitor for possible complications.[11]

Nasofrontal recess fractures

Nondisplaced fractures involving the floor of the FS or anterior ethmoid region should raise suspicion for nasofrontal recess (NFR) injury.

In the absence of associated FS injuries, close observation and repeat CT at 4-6 weeks may reveal sinus opacification, indicating outflow obstruction.

If NFR injury is highly suspected, but it cannot be confirmed on the CT scan, a frontal sinusotomy and endoscopic evaluation is indicated (see Intraoperative Details).

Displaced fractures usually require FS obliteration. Some authors have advocated more conservative approaches, such as NFR reconstruction with mucoperiosteal flaps (eg, Sewell-Boyden flaps) or intersinus septectomy, which theoretically allows the injured sinus cavity to drain into the uninjured NFR. These techniques have not gained significant popularity.

Anterior table fractures

Nondisplaced fractures can generally be managed nonoperatively. Nondisplaced anterior table fractures rarely result in mucocele formation, functional deficit, or aesthetic deformity. Advise patients of a small risk of external deformity, which can often be repaired endoscopically.[12]

Displaced fractures greater than 1-2 mm have an increased risk of aesthetic deformity and mucocele formation. ORIF of the fracture is indicated within 7-10 days.

• Consider endoscopic NFR evaluation through the fracture site or via trephination.

• Anterior table fractures with only mild comminution can be repaired with preservation of FS function; however, injuries with severe comminution and marked mucosal injury may require bone grafting and FS obliteration.

A study by Spinelli et al indicated that percutaneous screw placement can effectively be used for closed reduction of isolated fractures of the anterior frontal sinus. In the report, 15 patients with such fractures were treated with this technique.[13]

Posterior table fractures

Treatment of posterior table fractures remains controversial. A review of the literature reveals that some authors advocate exploration of all posterior table fractures, no matter how slight. Others recommend observation even when the posterior table is significantly displaced. No prospective randomized studies are reported to corroborate the different approaches.

Nondisplaced fractures have a reduced risk of complications (eg, dural tears, CSF leak, meningitis, mucocele formation) when compared with displaced posterior table fractures. The need for exploration often depends on the presence or absence of a CSF leak.

• CSF leak absent: When possible, patients should undergo frontal sinusotomy and endoscopic evaluation of the posterior table integrity. Sinus endoscopy is helpful to rule out mucosal injury, dural tear, CSF leak, or NFR injury. If the examination results are negative, the patient can be observed.

• CSF leak present: Patients with active CSF leaks may be observed for 5-7 days while undergoing treatment with IV antibiotics. Approximately half of these patients have spontaneous resolution of the CSF leak. FS obliteration is indicated if the CSF leak is persistent.

Displaced fractures have an increased risk of complications and require a more aggressive approach.

• CSF leak absent: Categorize cases by the severity of posterior table comminution. If no comminution is present, frontal sinusotomy and endoscopic evaluation for medial fractures is indicated. Obtain patient consent for an osteoplastic flap with possible obliteration or cranialization in case the injury is more severe than anticipated. Mild comminution requires osteoplastic flap and sinus obliteration. Moderate-to-severe comminution (ie, >30% of the posterior table) requires cranialization. Use a pericranial flap for dural repair as necessary. Consult a neurosurgeon for assistance with brain debridement and dural closure.

• CSF leak present: Patients should undergo open exploration with an osteoplastic flap. If minimal-to-mild comminution is present, sinus obliteration is indicated. Moderate-to-severe comminution requires sinus cranialization.

All patients undergoing open FS procedures should be counseled regarding potential risks, including the following:

• External scar, particularly in patients with male pattern baldness

• Bleeding

• Infection

• Forehead paraesthesias

• External deformity

• Diplopia

• CSF leak

• Meningitis

• Sinusitis

• Mucocele formation

• Death

Frontal sinusotomy and endoscopy

Make a 1- to 1.5-cm skin incision placed midway between the medial canthus and the glabella, approximately 1 cm inferior to the brow. The incision is well hidden when placed inferior and deep to the curve of the brow.

• The incision can be placed laterally and above the brow to access lateral portions of the FS.

• The surgeon should use a FS template (see FS obliteration, below).

• The surgeon should also attempt to avoid the supratrochlear neurovascular pedicle.

A guarded needle-point monopolar electrocautery is used to incise the periosteum. Use a cutting burr to open a 4- to 5-mm frontal sinusotomy approximately 1 cm medial and inferior to the medial brow. Incise FS mucosa; instill oxymetazoline for decongestion, if necessary.

Direct visualization of the NFR is obtained with a nasal endoscope to document any mucosal laceration or CSF leak.

• Methylene blue or fluorescein can also be instilled into the FS to confirm patency.

• Intranasal endoscopy will reveal the presence of dye if the NFR is patent.

Avoid NFR instrumentation because it may result in NFR stenosis. The procedure can be repeated on the contralateral side if necessary. The FS trephine procedure is limited by FS anatomy. Lateral fractures and intersinus septations may limit visualization.

ORIF

Position patient 180° away from anesthesia. Explore all forehead lacerations. Although lacerations alone are usually inadequate for exposure, diagnosis, and repair of FS fractures, they should be used to assist with fracture repair.

For coronal flap dissection, part the hair in a widow's peak pattern 4-6 cm behind the anterior hairline. A 1- to 2-cm strip of hair can be shaved along the incision line, but this is not necessary. The scalp is incised and elevated in a subgaleal plane. Avoid brow incisions to prevent prominent scars and forehead anesthesia.

Lateral flap dissection is performed between the temporoparietal fascia (superficial temporal fascia) and the temporalis muscle fascia (deep temporal fascia). The temporoparietal fascia and frontal branch of the facial nerve are elevated with the flap. The temporalis muscle fascia can also be incised and elevated with the flap to provide an extra layer of protection for the facial nerve.

Identify and protect the supraorbital and supratrochlear neurovascular pedicles.

The pericranium is incised 1-2 cm above the sinus and elevated below the fracture. If any concern about a posterior table injury or dural tear exists, elevate the entire pericranial flap from the coronal incision line. The vascularized pericranial flap may then be used for a dural repair.

Reduce the concave fracture segments. If the fracture segments overlap, a bone hook can be insinuated between the fragments and pulled forward.

• If the bone fragments do not overlap, fracture reduction can be difficult. The traumatic force applied to the FS results in horizontal compression of the bone. As the frontal bone fractures, it releases into a concave shape, as shown below.

  The compressive force of frontal bone as the bone is deformed from a convex shape to a concave shape.

• In this case, fracture reduction can be accomplished by placing a 1.7-mm screw in the depressed segment, grasping the screw with a hemostat, and pulling the segment anteriorly).

• Careful removal of a fragment may need to occur to reduce the tension along the fracture line. Attempt to keep most of the fragments in place because this allows for a more accurate final reduction.

• After the fracture is reduced, remove any torn mucosa from fracture lines to avoid entrapment and evaluate the sinus and NFR endoscopically.

• Reconstruct gaps larger than 5 mm with split calvarial bone grafts and bone pate harvested from the frontal bone with a cutting burr. Other techniques for anterior table reconstruction include combinations of titanium mesh, resorbable mesh, and hydroxyapatite cement.[14]

• After fracture reduction, plate the reduced fragments with 1- to 1.2-mm microplates.

• Close the pericranium, galea aponeurosis, and skin in a layered fashion. Insert two Penrose drains and a pressure dressing. Take care to assure that the ears are not rolled forward under the pressure dressing.

FS obliteration

Preoperatively, obtain an anterior-posterior plain radiograph (ie, Caldwell projection) of the skull. Alternatively, a surgical navigation system can be used intraoperatively to localize the sinus.

Prepare the patient for a coronal flap and abdominal fat graft.

Confirm the orientation of the Caldwell radiograph by comparison with a CT scan. Cut out a FS template from the Caldwell radiograph. Lateral "wings" paralleling the orbital rims should be left in place, as in the image below. To assist with accurate intraoperative placement of the template, an "R" should be scratched into the right side of the template.

Perform a coronal incision and elevate a scalp flap (see ORIF). If the anterior table of the FS is not comminuted, the FS template is applied over the pericranium. Tattoo an outline of the FS on the bone with an 18-gauge needle and methylene blue. Incise the pericranium in the coronal plane. Make parallel lateral cuts along the temporal line and raise a large inferiorly based pericranial flap. Take care to maintain a wide pedicle and avoid perforation of the flap.

The midline elevation should continue to approximately 1 cm below the outline of the FS.

A drill can be used to perforate the outline of the flap. Angle the drill toward the sinus cavity to avoid intracranial penetration and injury. The perforations can then be joined with an oscillating saw. A high-speed Midas Rex drill with a B-1 bit is efficient and obviates the need for an oscillating saw.

A 4-mm osteotome is used to fracture the superior orbital rims and glabella at the periphery of the sinus. Avoid injuring the supraorbital/supratrochlear neurovascular pedicles.

A curved osteotome is then placed through the saw kerf, and the intersinus septum is fractured. Repeat this step around the periphery of the sinus with multiple osteotomes until the anterior table of the sinus is hinged open inferiorly. The use of several osteotomes allows the surgeon to repeatedly place a new osteotome without losing the purchase from the previous one.

Assess the posterior table comminution and make a decision regarding sinus obliteration or cranialization. If the sinus is to be obliterated, meticulously debride all mucosa from the sinus with cutting and diamond burrs. Loop magnification can assist with the debridement. Pay particular attention to the periphery of the sinus and the NFR. Treat free bone fragments in a similar fashion. The FS infundibulum mucosa is elevated inferiorly, and a temporalis muscle plug is placed to occlude each ostia. Small sinus cavities can be obliterated with the pericranial flap. A small amount of bone is first removed from the inferior portion of the bone flap. The vascularized pericranial flap is then passed through the bony defect into the sinus cavity.

If fat is to be used to obliterate the sinus, obtain a fat graft through a periumbilical incision using sterile instruments. After fat graft placement and closure of the osteoplastic flap, the fat should approximate but not extrude from the saw kerf. Other materials used for FS obliteration include cancellous bone and muscle. The use of hydroxyapatite cements is not recommended until further studies are complete.

Spontaneous osteoneogenesis and auto-obliteration have also been advocated.

• Anterior table stabilization is achieved with 1- to 1.2-mm plates.

• Harvest bone pate from the frontal bone to fill the osteotomy kerf and any bony defects in the anterior table. Cover the bone pate with Gelfoam.

• Close the pericranium and scalp as described above.

A study by Lee et al reported that in frontal sinus obliteration for traumatic anterior table frontal sinus fractures accompanied by nasofrontal duct injury, the use of computed tomography (CT)-scan guidance permits more accurate osteotomy procedures than does the employment of plain radiographic templates or the “cut-as-you-go” technique. The study, which included 29 patients, found no perioperative complications in those whose surgery involved CT-scan guidance. In contrast, complications, including inadvertent dural exposure and the need for exposure-related hardware removal, occurred in the radiographic template and cut-as-you-go groups.[15]

FS cranialization

The surgical approach for cranialization is identical to that described for FS obliteration. Exposure of the sinus rarely requires osteotomies because of the severity of the anterior table injury.

Remove posterior table bone by using elevators and rongeurs. Large pieces of posterior table bone should be divested of mucosa and preserved for reconstruction of the anterior table during closure. Cleanse grossly contaminated bone fragments and soak the fragments in Betadine until needed for reconstruction. The posterior sinus margin is then drilled flush with the anterior cranial fossa. Each FS infundibulum is drilled out, the mucosa is inverted, and the ostium is occluded with a temporalis muscle plug.

Simple lacerations of the dura can be repaired with interrupted 5-0 nylon sutures. More complex injuries may require neurosurgical debridement and dural closure with a pericranial flap. A small bony defect must be fashioned in the anterior table to allow the pericranial flap to pass intracranially without cutting off the blood supply.

Cleanse the preserved bone fragments with saline and reconstruct the anterior table using 1- to 1.2-mm microplates. Outer table calvarial bone grafts should be used as necessary to supplement native bone. Close the scalp in layers. Place drains and a pressure dressing as described above.

Penrose drains are removed after 24 hours. Pressure dressing is discontinued after 3 days. Skin sutures and staples are removed after 10-14 days.

The need for long-term follow-up of patients with FS fractures cannot be overemphasized. The risk of late mucocele formation is significant.

Perform repeat CT or MRI if the patient has symptoms of recurrent infection. Trephination may be necessary in rare cases because radiographic identification of an infected fat graft is difficult.

Improper management of FS and NFR injuries can result in significant complications, including aesthetic deformity, forehead paresthesia or anesthesia, chronic sinusitis, mucopyocele, diplopia, visual loss, meningitis, brain abscess, and death.

Management of postoperative mucoceles usually involves a revision obliteration procedure or sinus exenteration (ie, Reidel procedure) with subsequent cranioplasty.

Patients with mildly displaced anterior table fractures do extremely well after surgical repair, and significant long-term sequelae are uncommon.

Displaced FS fractures generally result from more extreme forces. Consequently, most patients who undergo surgical treatment of these injuries have some long-term sequelae. The most common sequelae are mild and include frontal headache (20%), sinus infections (12%), sinus fullness (11%), sinus drainage (10%), and forehead depression (10%). Less common but more severe long-term sequelae include diplopia (4%), seizures (4%), mucocele formation (exact incidence uncertain [0-10%]), and brain abscess (1%).

For excellent patient education resources, see eMedicineHealth's Headache and Migraine Center and First Aid and Injuries Center. Also, visit eMedicineHealth's patient education articles, Sinus Infection and Facial Fracture.

The most common controversies associated with FS trauma are the aggressiveness of surgical repair for a given fracture type and the optimum material used for FS obliteration. Unfortunately, long-term follow-up in patients with FS fractures is extremely difficult. Definitive studies on the most efficacious management do not exist.

The author(s) has proposed a conservative treatment algorithm to guide the surgical repair of given fracture types. When obliteration is indicated, the author prefers autologous fat. Other materials that have been used include muscle, bone, fascia, osteoneogenesis (auto-obliteration), hydroxyapatite cement, and bioactive glass. Although autologous fat does have donor site morbidity, it is readily available, easy to handle, and cost-effective. Most importantly, it has long-term proven efficacy.

A similar algorithm that advocates observation of nondisplaced anterior table fractures that do not demonstrate radiographic evidence of nasofrontal recess obstruction has recently been suggested after reviewing 857 patients.[5]