Plastic Surgery for Frontal Sinus Fractures

Fractures of the frontal sinus pose certain treatment dilemmas to the facial trauma surgeon. Their mismanagement may lead to potentially life-threatening intracranial complications, most commonly meningitis, encephalitis, and brain abscess. Other complications include frontal osteomyelitis, frontal bone non-union, cavernous sinus thrombosis, cerebrospinal fluid (CSF) leak, mucopyocele, and meningoencephalocele.[1, 2]

These injuries are currently managed by various medical specialists, including otolaryngologists/head and neck surgeons, maxillofacial surgeons, plastic surgeons, and neurosurgeons. As a result, consensus does not exist regarding the timing, indications, and treatment modality of these injuries. The series reported in the literature have relatively few subjects and, as might be expected, mostly limited follow-up periods.

In the past, roentgenograms were used for diagnosing frontal sinus fractures, although the sensitivity of plain films was well-recognized as not very high.[3] Roentgenography can result in underdiagnosis and is not particularly useful in examining the severity of damage to the posterior table and the nasofrontal duct region.[4]

The use of high-resolution, 1.5-mm axial and coronal thin-cut computed tomography (CT) scanning provides improved diagnostic power for assessing injuries to the frontal sinus and midface[4, 5, 6] and has become invaluable in the diagnosis of frontal sinus fractures. Involvement of the nasofrontal duct is not easily discernible with CT imaging and, as a result, decisions regarding management of the nasofrontal duct and frontal sinus are frequently made during surgical exploration. However, nasofrontal duct injury is strongly suggested when the CT scan demonstrates involvement of the base of the frontal sinus, the anterior ethmoid complex, or both.[4] The nasofrontal duct complex should be evaluated in both the axial and coronal planes.

The progression of frontal sinus surgery stems from the first ablative procedure described by Reidel in 1898.[7] He described total exoneration of the sinus by removing the anterior table and floor of the sinus, allowing the skin to overlay the posterior table. This technique created an obvious marked cosmetic defect. In 1904, Killian described a similar procedure, but this procedure left a 10-mm rim of supraorbital bone, improving the cosmetic result.[8]

In 1921, Lynch described the first frontoethmoidectomy, leaving the anterior table intact but completely removing the ethmoid sinuses and the frontal sinus floor.[9] An indwelling catheter was inserted for prolonged drainage.

In 1951, Bergara and Itoiz devised the osteoplastic flap procedure.[10] They described exposure of the sinus by removing the anterior table, but, unlike Reidel, it was left hinged to an inferiorly based pedicle of pericranium. The flap was replaced at the end of the procedure. This technique resulted in a marked improvement in the overall aesthetic result.

In the late 1950s and 1960s, Goodale and Montgomery first described the ablative frontal sinus procedures that are the basis for current surgical obliterative management of frontal sinus fractures.[11, 12, 13] They took the osteoplastic flap procedure one step further, describing methods of ablating the frontal sinus by grossly removing all sinus mucosa and packing it with autogenous fat, essentially eliminating the sinus as a functional unit.

Later work described the involvement of the nasofrontal ducts in chronic complications of frontal sinus trauma, presumably secondary to duct stenosis.[3] It then became clear that simple obliteration as described by Goodale and Montgomery was insufficient to completely prevent the occurrence of late sequelae. The importance of removing any retained mucosa in the region of the nasofrontal duct was stressed.[3, 14] Failure to remove all sinus mucosa and subsequent reepithelialization of the sinus was demonstrated to result in late complications such as mucoceles and mucopyoceles.

Donald and Bernstein described the first cranialization procedure in 1978.[15] It involved stripping the sinus of all mucosa, plugging the nasofrontal ducts, and removing the posterior table, allowing the brain to expand into the frontal sinus space; the procedure thus incorporated the previous frontal sinus space into the anterior cranial vault. This procedure is still used today, but it is usually reserved for patients with severe comminution of the posterior table.

Frontal sinus fractures can be classified into fractures of the anterior table, the posterior table, or both. Isolated fractures of the posterior table are rare. The fractures may be simple, comminuted, displaced, or nondisplaced. Displacement of anterior table fragments, especially when through the inferior and/or base half of the sinus, can cause obstruction of the nasofrontal duct.[3] Displacement of the anterior table can also lead to depression of the forehead and a cosmetic deformity (see following images).

Posterior table fractures usually occur in combination with fractures of the anterior table and are frequently associated with intracranial trauma. When the posterior table is displaced more than the width of the table, the incidence of CSF leak and dural tears is high. Impinged sinus mucosa between fracture segments may lead to the formation of mucoceles.[16] The frequency of nasofrontal duct injury is proportional to the severity and comminution of the frontal sinus fracture. Injuries to the duct are likely when the fracture is medial to the supraorbital notch and involves the base of the frontal sinus and/or the anterior ethmoid complex (see following images). Unrecognized injury to the nasofrontal duct may lead to frontal sinus drainage and aeration obstruction and, eventually, the formation of mucoceles, mucopyoceles, meningitis, and intracranial abscess.

A study by Garg et al indicated that vertical frontal bone fractures that extend into the frontal sinus and orbit or into the middle or posterior cranial fossa have greater complication and mortality rates than do nonvertical frontal sinus fractures. The study involved 149 frontal bone fractures, including 51 nonvertical frontal sinus fractures and 98 vertical fractures with or without frontal sinus involvement.[17]  

Frequency

Frontal sinus fractures comprise 5-12% of maxillofacial traumas.[3, 18] The incidence appears to be approximately 9 cases per 100,000 adults.[19]

Fractures of the frontal sinus occur most commonly as a result of blunt trauma from a motor vehicle accident; the next most common cause is high-impact sports-related injury.[20, 19, 21, 22] Frontal sinus fractures may result from low-velocity, high-velocity, blunt, or penetrating trauma. With low-velocity impact, the anterior table may confer some protection to the posterior table and may be the only table to fracture. Conversely, high-velocity or penetrating trauma may cause severe damage to both the anterior and posterior tables, with comminution and significant displacement.[23]

The force required to fracture the frontal sinus has been reported to be 800-2200 lb of force and is usually sufficient to cause significant associated injuries.[24] There is no association between age and the fracture force required.[25]

Patients presenting with this type of injury usually have associated craniofacial trauma, which must be treated in an appropriately triaged fashion. Patients may present in a coma 20-76% of the time, depending on the series studied.[19, 22, 23] As many as 93% of patients present with multiple associated facial fractures, skull fractures, or both.[19, 23] In one series, 20% of patients presented with CSF rhinorrhea.[22]

A fracture of the frontal sinus should be considered clinically when a gross depression or laceration is found over the supraorbital ridge, glabella, or lower forehead, as this is the most common finding on clinical examination.[4] Lacerations should be examined gently to determine if any bony step-offs are present. As many as 59% of these patients may present with orbital trauma.[14] Prompt ophthalmologic evaluation may be necessary. A large percentage of patients also may have associated fractures of the naso-orbito-ethmoid complex and midface, which may also suggest involvement of the nasofrontal duct. Gross CSF rhinorrhea may occur if the posterior table of the frontal sinus and the dura are involved in the injury.

Although the management of frontal sinus fractures is somewhat controversial, certain treatment principles exist that are generally accepted.[26] Surgical treatment, if indicated, should be instituted within the first 12-48 hours after the injury, if this is compatible with the patient's overall clinical condition. Early treatment reduces the incidence of long-term complications[27] and is especially important for patients with CSF rhinorrhea because a significant increase in the rate of infection has been reported in patients in whom CSF leak persisted for more than 8 days.[28]

Isolated anterior table fractures are the most common type of frontal sinus injury (see following images).

Displacement of the fracture and depression of the anterior table are indications for surgical exploration and internal fixation. These fractures can result in cosmetic deformity and mucocele formation, and many consider them to be an absolute indication for surgery, especially if the displaced fracture involves the base of the frontal sinus or the anterior ethmoid complex, as such involvement is associated with a higher likelihood of nasofrontal duct obstruction. The nasofrontal duct can be explored through the existing fracture line or through a frontal trephination with sinus endoscopy. If the nasofrontal duct is involved, sinus obliteration is generally required.[22] If the nasofrontal duct is not involved, internal fixation is performed, and the patient is observed. Isolated, depressed anterior table fractures without nasofrontal duct injury may be percutaneously reduced using a specialized bony tapper device or simply using screws, forceps, and manual traction. This technique may be less invasive and more cosmetically favorable in patients with this simple type of fracture.[29, 30]

Most nondisplaced anterior table fractures can be managed expectantly and nonsurgically,[31] since these fractures are typically not associated with mucocele formation, although they may still result in cosmetic deformity.

Posterior table fractures are commonly associated with anterior table fractures. Treatment is usually dictated by the presence or absence of nasofrontal duct involvement, CSF leak, or both. In the case of posterior table fractures, most would advocate surgery in the presence of displacement more than one table width, and especially in the presence of gross CSF leak and associated dural tears not responding to conservative therapy (eg, bed rest). Many authors elect to closely observe patients presenting with posterior table fractures and CSF leak for 7 days. If observation and conservative management fail, exploration and repair are suggested.[22] Neurosurgical consultation for craniotomy and dural closure would then need to be obtained. Sinus obliteration or cranialization is concurrently performed.[32] Cranialization of the frontal sinus is usually reserved for severely displaced or comminuted fractures of the posterior table.[15, 21] However, a recent 10-year study by Choi et al demonstrated successful, nonoperative management of a majority of comminuted, displaced fractures with or without CSF leak.[33]

Newer protocols involving sinus preservation with endoscopic management of the nasofrontal duct have been described for specific cases. Proponents argue that sinus preservation may decrease morbidity, operative time, and risk of bone devitalization, as well as allowing the surgeon to endoscopically evaluate the sinus postoperatively. Larger studies are needed to evaluate these claims.[34]

The management of nondisplaced posterior sinus wall fractures is more controversial. Some authors suggest that all posterior table fractures should undergo exploration and be examined directly via sinuscopy or otherwise. Others treat these injuries with close observation and explore if complications (persistent CSF leak) develop.

Surgical indications are summarized in the above images.

The frontal sinuses are not developed at birth. They begin as an invagination of the anterior ethmoid air cells, which can be first appreciated radiographically in individuals aged 6-8 years.[35] Their pneumatization is usually asymmetric and may range from partial to incomplete in approximately 20% of the population.[35] They do not achieve full size until late adolescence. For this reason, fractures of the frontal sinuses are nearly twice as common in the adult population as in the pediatric population.[19]

The frontal sinuses are usually highly variable in size and shape. They are usually characterized by 2 asymmetric sinuses that are separated by a thin, bony septal plate. Hypoplasia of the frontal sinus is relatively common, with 2-20% of the population demonstrating some degree of underpneumatization. The nasofrontal ducts are situated posteromedially in the sinus and are the only drainage pathways of the frontal sinus. These may be absent in as much as 80% of the population; these persons simply have a large opening into the middle meatus.

When present, the ducts usually run caudally for up to 2 cm. Large anterior ethmoid cells, also known as the agger nasi cells, may bulge into the floor of the frontal sinuses and the nasofrontal ducts. Chronic inflammation in the adjacent thin-walled spaces of both the ethmoid and frontal recess air cells may lead to chronic edematous changes in the nasofrontal ducts, causing frontal sinus drainage problems. For this reason, patients with a history of recurrent anterior ethmoid sinusitis may be at higher risk of developing recurrent frontal sinus infections after trauma to the nasofrontal ducts.

Due to the proximity of important anatomic structures, early recognition and treatment of frontal sinus fractures is necessary. Inferiorly and posteriorly, the sinuses are in close apposition to the dura mater, frontal lobes, crista galli, and cribriform plate, usually separated only by a thin, bony plate. The anterior-superior portion of the sinuses is composed of the sturdier frontal bone.

Contraindications to surgical repair of a frontal sinus fracture include patient inability to undergo general anesthesia secondary to intracranial injuries, decreased mental status, hemodynamic instability, and pending treatment of other, more potentially life-threatening injuries. Often, many of these contraindications are present in patients with trauma to the frontal sinuses. Definitive surgical treatment of frontal sinus fractures is often delayed for these reasons.

In the past, roentgenograms were the basis for diagnosing fractures to the frontal sinus.[3] Admittedly, the sensitivity of conventional plain films was not considered to be very high.[3] Plain films are especially poor in defining the severity of damage to the posterior table and the nasofrontal duct region.[4]

The use of high-resolution, 1.5-mm thin-cut CT scanning provides improved diagnostic power for assessing injuries to the frontal sinus and midface.[5, 6, 4, 36, 37, 38, 39] Unfortunately, involvement of the nasofrontal duct is not clearly definable even with CT imaging; therefore, decisions regarding management of the duct and sinus are frequently made during surgical exploration. Certain findings on a CT scan image strongly suggest injury to the nasofrontal duct. A CT image that demonstrates a fracture through the base of the frontal sinus and/or the anterior ethmoid complex strongly suggests trauma to the nasofrontal duct.[4]

A study by Gala et al indicated that maxillofacial CT scanning can more effectively reveal anterior table frontal sinus fractures than head CT scanning can. Out of 47 of these fractures, head CT scanning identified 32, compared with all 47 for maxillofacial CT scanning. With regard to posterior table frontal sinus fractures, the success rate for head CT scanning did not significantly differ from that for maxillofacial scanning.[40]

Some authors have proposed obtaining a 6-foot Caldwell view plain film prior to surgical intervention. The goal is to obtain an image that depicts the exact dimensions of the patient's frontal sinuses. This film is then sterilized and used as a template to mark the exact location of the frontal sinuses intraoperatively when the frontal bone is exposed. The film assists in designing a precise osteoplastic flap. Take care to ensure that the dimensions of the skull correspond exactly to the patient.

The main goals of the surgical treatment of frontal sinus fractures are (1) protection of intracranial structures and the cessation of CSF leakage, (2) prevention of posttraumatic infections, and (3) restoration of facial aesthetics.

One may consider a 6-foot Caldwell view plain film prior to surgical intervention. An image is then obtained that accurately depicts the size and shape of the patient's frontal sinuses. This film is then sterilized and used as a template to mark the exact location of the frontal sinuses intraoperatively when the frontal bone is exposed. The film assists in designing a precise osteoplastic flap.

A study by Lee et al indicated that in patients undergoing repair of anterior table frontal sinus fractures, the use of computed tomography (CT)-scan guidance permits more accurate osteotomies and elevations of the anterior table than do the use of plain radiographic templates or a “cut-as-you-go” technique. The study, which involved 29 patients with acute, traumatic anterior table frontal sinus fractures and nasofrontal duct injury, found that osteotomies in the CT-scan guidance patients were 95% accurate, compared with 85% and 72.5% accurate in the plain radiographic template and cut-as-you-go patient groups, respectively.[41]

Appropriate consent must be obtained from the patient preoperatively. Sensation of the forehead must be documented, and the surgical approach must be determined prior to surgery.[42, 43, 44] Risks of the chosen approach must be discussed. For example, if the sinuses are to be explored via a bicoronal approach, frontal numbness, temporal hollowing, and scarring should be addressed.

The frontal sinus can be approached in many ways. Exposure through existing lacerations should be attempted first, but incisions through existing soft tissue defects or through the upper eyelid may provide limited exposure and access. The bicoronal incision offers better exposure of the frontal sinus and more easily permits the use of osteoplastic flaps and grafting materials for sinus obliteration. Some authors propose the pretrichial incision as a more aesthetic and equally valuable incision in particular situations.[45]

An endoscopic approach may also be used in certain cases. This approach decreases surgical and recovery time and avoids a large external bicoronal incision.[22] The use of this technique, while previously limited to the treatment of isolated simple anterior wall fractures,[46, 47] has now expanded to the repair of posterior table fractures with good results.[48] Computer-aided medical modeling has been described to facilitate access to the frontal sinus in complex cases. In this technique, 3-dimensional maxillofacial reconstruction technology is used to create a cutting guide, which outlines the anterior table. It is placed on the skull intraoperatively to aid the surgeon in precise cutting of the borders of the anterior table at its junction with the surrounding frontal bone.[49]

Standard practice is to repair fractures of the anterior wall if significant displacement is causing an external cosmetic deformity. The risk of cosmetic deformity is increased if the fracture depth is greater than 4 mm.[50] Exploration of the frontal sinus is indicated for nasofrontal duct injury when the fracture involves the floor of the sinus or the anterior ethmoid complex. After excluding nasofrontal duct injury, the anterior table should be repaired, most commonly with titanium or absorbable miniplates.If a large anterior table defect exists or the degree of comminution is high, grafting with calvarial cancellous bone is recommended. Iliac bone grafts have also been used with success.[51] The presence of improperly reduced segments, retained sinus bony fragments or foreign bodies, damaged sinus mucosa, and, in some studies, the use of synthetic grafting materials such as methyl methacrylate or hydroxyapatite may lead to infection.[18] Thus, one should take care to appropriatelyexplore,clean out, and reduce the frontal sinus fracture prior to repair.

Attempts to confirm nasofrontal duct injury are performed intraoperatively. The duct orifice may be probed gently. Alternatively, fluorescein dye or methylene blue may be administered in the duct after mucosal vasoconstriction. Duct obstruction is confirmed if fluorescein (or methylene blue) fails to emerge in the nose.[52] Alternatively, the nasofrontal duct orifice may be visualized indirectly with an endoscope through either the existing fracture site or a frontal trephination.

After confirmation of nasofrontal duct obstruction, most authors recommend ablation of the sinus.[3, 14, 18, 19, 20, 21, 23, 24, 35] Nasofrontal duct repair may also be attempted by intubating the duct for several weeks as described by Luce.[52] This approach may be associated with a 30% failure rate of duct patency after removal of the catheter, and, thus, is no longer commonly performed. Ablation is considered to be the safer treatment in the presence of nasofrontal duct injury because attempts to save an injured duct may be riskier in the long-term.[14, 15] Depending on the degree of comminution of the posterior table, cranialization is also an option for the treatment of nasofrontal duct injury and obstruction. Newer protocols involving sinus preservation with endoscopic management of the nasofrontal duct have been described for specific cases. Proponents argue that sinus preservation may decrease morbidity, operative time, and risk of bone devitalization,as well as allowing the surgeon to endoscopically evaluate the sinus postoperatively. Larger studies are needed to evaluate these claims.[53]

Gross CSF rhinorrhea is usually indicative of a dural tear and of injury either to the posterior table or, more commonly, the posterior inferior thin, bony cribriform plate. An exploration of these injuries is recommended, and, if possible, the dura should be repaired. Sinus cranialization or obliteration has been shown to be effective for management of the CSF fistula.[32, 54] Cranialization may be more beneficial in patients with severe comminution.

Folded pericranial flaps have been described to separate the nasal and frontal cavities in patients with injury to the cribriform plate.[12] These appear to prevent late complications that may occur from cribriform and dural injuries, such as meningitis and brain abscess.[12, 21]

Multiple materials, both autogenous and alloplastic, have been described for frontal sinus obliteration. Autogenous materials that have been used include fat, bone, muscle, and fascia. Alloplastic materials include Proplast, acrylic resin, Gelfoam, and methyl methacrylate. Overall, autogenous materials appear to be more successful than alloplastic materials in achieving obliteration and preventing long-term complications.[28] Anterior pericranial flaps have been suggested for frontal sinus and nasofrontal sinus duct obliteration owing to their benefits of vascularity and viability over avascular grafts such as fat, muscle, or bone.[55, 56] Latissimus dorsi myocutaneous free flaps have also been described for frontal sinus obliteration if local flaps are unavailable or infected.[57]

Certain procedures must be followed to ensure appropriate obliteration of the sinus and prevention of long-term sequelae, regardless of the type of material used.[23] First, the sinus mucosa must be completely removed. For this purpose, the use of surgical loupes and microscopes has been recommended. Second, all inner cortex bone should be removed from the sinus. Mucosa in the human frontal sinus is able to invaginate into pits of inner cortex bone. Donald described these as the vascular pits of Breschet.[58] Failure to remove mucosa from these pits can possibly lead to entrapment and late formation of mucoceles. To achieve this, a high-speed burr is recommended. Last, the nasofrontal duct should be occluded using either bone or pericranial fascia. A 20-year retrospective study by Pollock et al demonstrated a low complication rate of 6% after cranialization, which the authors attributed to thorough sinus mucosal debridement, complete obliteration of the nasofrontal duct, and avoidance of avascularbarriers such as abdominal fat.[59]

Isolated, depressed anterior table fractures without nasofrontal duct injury may be percutaneously reduced using a bony tapper device. The tapper is inserted into the depressed bone through a 3-mm incision without subperiosteal dissection. Traction is used for reduction. In a study by Yoo et al, of 13 patients who underwent percutaneous anterior table reduction, only 1 had a complication due to the procedure (pneumocephalus from involvement of posterior table). Alternatively, 2-mm screws can be used for simple percutaneous reduction and involves manual traction using forceps. This technique may be less invasive and more cosmetically favorable in patients with this simple type of fracture.[29, 30]

Postoperatively, the patient should be instructed to avoid contact and strenuous activities. The patient should seek medical attention if any swelling, tenderness, fever, or mental status decrease occurs because these may be signs of acute frontal sinusitis, with or without meningitis, which may occur in the early postoperative period secondary to retained bony chips or foreign materials in the sinuses. The patient benefits from routine wound care instructions.

For patients who have undergone repair and/or obliteration of the frontal sinuses, close monitoring (ie, every month) is recommended for the first year after the repair and annually thereafter. CT scans should be performed annually to detect complications in early stages.[22] Long-term follow-up care of these patients is mandatory.[28]

Complications of frontal sinus fractures may be life threatening. Both early and late complications may arise. An early complication is frontal sinusitis, most commonly resulting from retained foreign bodies or bony chips in the frontal sinus. If not recognized and adequately treated, this, in turn, may lead to meningitis, osteomyelitis, orbital abscess, or brain abscess.

Late complications may occur up to a decade after the injury.[18, 60, 61] These include mucocele, mucopyocele, and delayed CSF leak with or without meningitis. For this reason, patients who have undergone repair and/or obliteration of the frontal sinuses should be monitored closely the first year after the repair and then yearly thereafter. Long-term follow-up care is mandatory for these patients.[28] Any complaints of frontal pressure, pain, or headache should lead to an aggressive workup. Again, CT scanning provides the most accurate diagnostic information when evaluating a patient for complications.

Overall, if frontal sinus trauma is recognized adequately and patients receive an adequate workup and treatment, their prognosis is good. The management of the nasofrontal duct is key. Stanley reported on expected outcomes following repair of frontal sinus fractures.[62] For all patients treated with nonobliterative frontal sinus reconstructions, the complication rate was 10%. However, in patients treated with frontal sinus obliteration, the complication rate decreased to 1%. For this reason, a low threshold apparently should be present for deciding when to obliterate the frontal sinus in patients with injury to the nasofrontal duct.

Most reports in the literature have a poor follow-up record. Some of the series seem to support the notion of a 1-3% complication rate after repair.[14, 20] The most common complication appears to be meningitis.[63]

In the past, frontal contour defects were common after frontal sinus reconstruction. With the advent of titanium mesh, miniplates, and new grafting techniques, the overall aesthetic prognosis for these patients is good. Recently, endoscopic approaches with closure of defects using calcium hydroxyapatite have been performed with reportedly excellent cosmesis.[46, 47]

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

In summary, the treatment guidelines for patients with fractures of the frontal sinus, although not uniform, are mostly well established. Controversies exist regarding timing and indications for surgical intervention and regarding the best types of surgical ablative materials and procedures.

The recent introduction of newer bony, biocompatible, synthetic replacement materials with osteoinductive and osteoconductive properties is likely to add to this discussion. Endoscopic techniques and 3-dimensional reconstruction technology[64] continue to develop and may play a greater role in the treatment of more extensive fractures. The methods of ablative therapy and treatment algorithms presented are simply management guidelines, which may need to be modified in individual cases. Regardless of controversies, frontal sinus surgeons must be able to recognize injuries that require aggressive treatment. They then must be able to proceed with surgical treatment that renders the frontal sinus safe in the long-term. Prevention of potentially life-threatening complications is critical.