CRANIOFACIAL Management of Frontal Sinus Fractures Spiros Manolidis, M.D. Larry H. Hollier, Jr., M.D. New York, N.Y.; and Houston, Texas
Summary: Frontal sinus fractures are relatively uncommon maxillofacial injuries, making up only 5 to 12 percent of all facial fractures. Associated intracranial, ophthalmologic, and other maxillofacial injuries are very common because of the force of injury required to fracture the frontal bone. High-resolution computed tomography of the frontal region in multiple planes is essential for predicting the degree of frontal injury, associated injuries, and the type of procedure indicated. Exploration of the frontal sinus with reduction alone is reserved for a small minority of very simple fractures. Most frontal sinus fractures will require the obliteration of the sinus. This is achieved in the majority of instances with preservation of the posterior wall. Those with more extensive injuries and the presence of a cerebrospinal fluid leak will require frontal sinus cranialization after repair of the dural injuries. In rare instances, primary bone grafts will be required. In both cranialization and obliteration procedures, the nasofrontal ducts must be managed appropriately to avoid complications. Newer techniques involving endoscopic image-guided surgery may offer an alternative for a small subset of patients with frontal sinus injury. (Plast. Reconstr. Surg. 120 (Suppl. 2): 32S, 2007.)
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rontal sinus fractures account for 5 to 15 percent of all maxillofacial fractures.1,2 Assaults and vehicular trauma account for the majority of frontal sinus injuries. Frontal sinus fractures have been associated with severe maxillofacial and systemic injuries, with a high rate of morbidity and mortality.3,4 The management of frontal sinus injury is an important topic, as inappropriate management of these injuries not only leads to cosmetic deformities and functional problems but may give rise to serious complications, including the development of mucoceles, osteomyelitis, and potentially fatal central nervous system complications such as meningitis and brain abscesses.1,5,6 Several aspects of frontal sinus injury treatment remain controversial secondary to the relatively small numbers of patients reviewed in the literature and the difficulty in maintaining long-term follow-up in these patients.6 Areas of controversy include the roles of frontal sinus obliteration, cranialization, and nasofrontal duct stenting in the acute trauma setting.7
BIOMECHANICS The frontal bone is the strongest component of the craniofacial skeleton. It can withstand beFrom the Department of Otolaryngology–Head and Neck Surgery, Beth Israel Hospital, and Baylor College of Medicine and Department of Plastic Surgery, Ben Taub General Hospital. Received for publication May 8, 2006; accepted January 18, 2007. Copyright ©2007 by the American Society of Plastic Surgeons DOI: 10.1097/01.prs.0000260732.58496.1b
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tween 800 and 2200 pounds of force before fracturing.8 In an average size adult human, these forces can be reached with a frontal collision at 30 mph for an unrestrained passenger.9,10 Because of its projection and the large surface area it occupies relative to the rest of the facial skeleton, the frontal region is frequently the first site of exposure in both vehicular and assault injuries. The anterior table of the frontal sinus is the stronger component of the two bone tables of the frontal sinus because of its overall thickness, especially along the supraorbital buttress. The posterior table is thinner and is not part of this buttress system. The dura is densely adherent to the deep surface of the posterior table. The dura becomes thinner and more adherent along the caudal edge, where it turns to cover the roof of the ethmoid air cells (fovea ethmoidalis). When significant fractures of the frontal bone occur, these propagate easily and extensively along the orbital and nasoethmoid complexes, which have significantly weaker tolerances.9,10 Injuring forces capa-
Disclosures: Neither of the authors has received funds or support or has a financial interest in any of the products, devices, or drugs mentioned in this article. Dr. Manolidis lectures as part of the faculty for the North American AO-ASIF group and for that, in the past, has received stipends for attending/lecturing at their educational conferences.
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Volume 120, Number 7 Suppl. 2 • Frontal Sinus Fractures ble of disrupting the anterior table will frequently involve the posterior table and the elements of the floor of the anterior cranial fossa: the fovea ethmoidalis and cribriform plate. Injuring forces capable of disrupting the anterior table will frequently involve the posterior table and the elements of the floor of the anterior cranial fossa: the fovea ethmoidalis and cribriform plate. This leads to the common intraoperative finding of comminuted anterior table with posterior table fractures and associated dural tears capable of producing cerebrospinal fluid leaks. The nasofrontal duct opening usually lies in the posteromedial floor of the sinus and runs caudally to the anterior middle meatus. Significant anatomical variations exist in the width, length, and shape of the nasofrontal duct.7 These anatomical variations make it difficult to predict with accuracy the future functioning of the nasofrontal duct in the face of frontal sinus injury. In addition, forces that are capable of fracturing the supraorbital buttress will frequently cause comminuted, displaced fractures of the superior orbital rim that typically involve the frontonasal duct. These fractures are associated with a disproportionate number of ocular injuries and other orbital injuries with long-term effects on vision.11,12 Occasionally, fractures of the frontal region will extend to the skull base beyond the anterior cranial fossa into the middle cranial fossa fractures that course through the foramina of the skull base. In severe injuries, attention should be given to the temporal bone, as these fractures can extend through the temporal bone with severe consequences for both hearing and facial nerve function, and with the potential for a cerebrospinal fluid leak through the temporal bone.2,13 Occasionally, forces will be transmitted through the anterior table, without its fracturing, to structures posterior to it. Such patterns of injury account for isolated nasofrontal duct injuries, with subsequent frontal sinus complications if left untreated.14,15 Rarely, such forces can be transmitted more posteriorly to involve the optic canal or the superior orbital fissure, causing visual loss and/or superior orbital fissure syndrome, respectively16–18 (Fig. 1). The geometry of the impact is also a significant factor in frontal sinus fractures. Sharp objects that impart much greater force in a smaller surface area and blunt heavy objects that transfer larger amounts of energy will cause increasing amounts of trauma, such as that commonly seen in assault. Gunshot injuries, especially high velocity, and industrial accidents will invariably fracture both anterior and posterior tables of the frontal sinus and
Fig. 1. Fractures involving the superior orbital fissure and optic canal region (left side) and the lateral orbital wall posteriorly at the region of the superior orbital fissure (right side). This patient presented with minimal frontal sinus trauma and bilateral loss of vision.
breach the anterior cranial fossa. Under these circumstances, posterior table fractures are invariably associated with dural tears and fractures extending to the anterior cranial base to involve the cribriform plate and fovea ethmoidalis.
ANATOMY AND EMBRYOLOGY The frontal sinus is in critical approximation to anatomical structures, which underscores the importance of its management in injury. Posteriorly, the cribriform plate, dura mater, and frontal lobes are in close apposition to one another and to the posterior wall of the sinus. The dura is densely adherent to the deep surface of the posterior table and becomes more adherent and thinner along the caudal edge, where it turns to cover the fovea ethmoidalis. The frontal sinus develops starting at infancy from the middle meatus, with continuous growing through early adulthood, attaining an average volume of 5 cm3. The frontal sinuses are absent at birth and do not begin to develop until the second year of life.19 The frontal sinus itself cannot be identified radiographically until approximately the age of 8 years, and it does not reach adult size until age 12 years or older. In 10 percent of persons, the frontal sinus develops unilaterally, in 5 percent it is a rudimentary structure, and in 4 percent it is absent altogether, so that almost one-fifth of individuals have aberrant sinus development.20 The frontal sinuses develop from the ethmoid infundibular air cells by invagination of the frontal bone through the frontal recess or from the superior meatus21 (Fig. 2). The size of the adult frontal sinus shows exceptional variability in the degree of pneumatization. Sinus pneumatization begins from the
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Plastic and Reconstructive Surgery • December Supplement 2, 2007
Fig. 2. Development of the frontal sinus through invagination of the frontal bone by ethmoidal air cells.
nasal part of the frontal bone by several ethmoid air cells at once, which are termed frontal bullae. This multiplicity of pneumatization results in variability and tortuosity of the frontal sinus drainage pathway (nasofrontal duct). An intersinus septum separates the two sides. The frontal sinus may consist of one or more compartments, depending on the source of pneumatization. The intersinus septum, which separates
these compartments, is continuous with the crista galli inferiorly, whereas its superior attachment to the sinus walls is frequently asymmetrical. When this septum is asymmetrical, the crista galli shows varying degrees of pneumatization and protrusion within the sinus. In this situation, a surgical risk exists for entering the anterior cranial fossa at the cribriform plate (olfactory groove) if this area is mistaken for the posterior wall of the frontal sinus (Fig. 3). The lateral floor of the frontal sinus is the roof of the orbit, whereas the medial floor of the frontal sinus contains the opening of the nasofrontal duct.7 The nasofrontal duct is the exclusive drainage of the frontal sinus and thus of utmost clinical significance in the management of frontal sinus injury. Its course is highly variable, running caudally from a few millimeters to up to 2 cm.22 A true identifiable duct may be absent in up to 85 percent of frontal sinuses. In this situation, the frontal sinus drains indirectly through ethmoid air cells to the middle meatus7 (Fig. 4). The nasofrontal duct terminates at the uncinate process in the nasal cavity, which is a thin bone plate that is covered on either side by mucosa. On computed tomographic scans, the inferior portion of the uncinate process is mostly visible, whereas the superior portion of the uncinate
Fig. 3. Variations in the depth (relative downward displacement of the cribriform plate) is related to the location of the fovea ethmoidalis, that is, the pneumatization of the ethmoid air cells. In this figure, the fovea ethmoidalis is the intracranial surface that overlies the ethmoid air cell labyrinth.
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Volume 120, Number 7 Suppl. 2 • Frontal Sinus Fractures
Fig. 4. Sagittal transparency view of the nasofrontal duct and its relation to the ethmoidal labyrinth. Drainage is through the hiatus semilunaris underneath the middle turbinate.
process cannot be identified in up to 40 percent of cases.23 There are two identifiable patterns of drainage of the frontal sinus. When the uncinate process is attached to the lamina papyracea, the drainage is medial to the uncinate process through the middle meatus. This type of drainage pattern is seen in 66 to 88 percent of cases.20,24 When the uncinate process attaches superiorly to more medial structures (middle turbinate, cribriform, or skull base), the drainage of the sinus is lateral to the uncinate process. This type of drainage pattern is seen in 12 to 34 percent of cases.24,25 A significant feature of the frontal sinus is the mucosal lining, which is contiguous with that of the ethmoid air cells and nasofrontal ducts. The mucosal lining of the frontal sinus consists of ciliated columnar epithelium. The cilia of these cells are bathed by a proteinaceous solution (mucus). Through ciliary motion, this mucous layer moves in a clockwise fashion toward the nasofrontal duct, from where it is ultimately expelled into the hiatus semilunaris and then nasal cavity (Fig. 5). The frontal sinus is unique in that it is the only sinus that has a recirculation phenomenon. The mucus travels along the lateral side of the sinus and turns medially over the sinus floor and down the lateral frontal recess wall. Of the secretion, 60 percent is directed back into the sinus cavity as it reaches the frontal recess.26 Mucus is produced by goblet cells interspersed in the ciliated mucosa of the frontal sinus. Clinically significant anatomical structures of the mucosa of the frontal sinus are the foramina of Breschet, first described over 60 years ago.27 These foramina are
Fig. 5. Mucociliary flow of the frontal sinus, invaginations of mucosa into the bone at the foramina of Breschet.
sites of venous drainage of the mucosa and can serve as the route of intracranial spread of infection.3 The mucosa is found deeply invaginating these foramina. If mucosa is not completely removed microscopically from these foramina in obliteration or cranialization procedures, there is a high risk of mucocele formation.28 –31
CLASSIFICATION OF INJURIES Numerous classification schemes of frontal sinus fractures have been described. The lack of uniformity in treatment and small numbers of such injuries have contributed to this situation. Most classifications are based on anatomical location and observations of intraoperative findings in comparison with preoperative evaluations by high-resolution computed tomography.1,32,33 Early work by Manson and others derived classification schemes of frontal and midface injuries based on these principles that are in wide use today.34 –36 Elaborate classification schemes with multiple subdivisions do not add significantly in the management of frontal sinus injuries, as the operative options are limited.37 Most authors agree that three components related to the frontal sinus must be taken into account: the anterior table, the posterior table, and the nasofrontal duct.1,7,15,33,38 In addition, injury to the dura, presence of cerebrospinal fluid leak, and open cerebral trauma, most frequently associated with tissue loss, must be taken into account in a classification of frontal sinus injury. Three further observations can simplify the classification of frontal injuries: (1) isolated posterior table fractures are rare entities of questionable significance; (2) involvement of the anterior and posterior tables in-
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Plastic and Reconstructive Surgery • December Supplement 2, 2007 variably leads to frontonasal duct injury; and (3) involvement of the nasoethmoid complex and medial orbital rim in the fracture pattern also invariably leads to frontonasal duct injury.32,33 A classification scheme that might include these principles would appear similar to that presented in Figure 6.
ASSOCIATED INJURIES Ocular Injuries Ophthalmologic injury is seen in as many as 25 percent of those with frontal sinus injuries. The range of these ophthalmologic problems in these
Fig. 6. Classification of frontal sinus injuries: type 1, linear, minimally displaced fractures of the outer wall; type 2, comminuted or depressed anterior table fractures (may or may not involve the nasofrontal duct); type 3, both anterior and posterior frontal sinus walls involved by comminuted fractures; type 4, comminuted anterior and posterior wall fractures with dural injury and potential cerebrospinal fluid leak; and type 5, comminuted anterior and posterior wall fractures with dural injury and potential cerebrospinal fluid leak in addition to tissue and/or bone loss. (Reprinted with permission from Semin. Plast. Surg. 16: 2002.)
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Volume 120, Number 7 Suppl. 2 • Frontal Sinus Fractures patients is wide. The most common abnormal finding, in up to 10 percent of those with a frontal sinus fracture, is an afferent pupillary defect secondary to optic nerve involvement (Fig. 1). Such optic nerve involvement must be assessed carefully by high-resolution computed tomography. The management of optic nerve involvement by highdose steroids versus optic nerve decompression is controversial. The treatment of optic nerve involvement supersedes the correction of frontal sinus fractures with the exception of central nervous system injury requiring acute management, severe soft-tissue loss, and/or exposure of brain parenchyma. Involvement of the superior orbital rim and/or orbital roof will increase the chance of ocular injury to 25 percent.11,39 The most significant of these injuries, open globe or globe rupture, though rarely seen, is usually a devastating injury that results in visual loss. In this situation, concurrent enucleation must be considered along with preparation of the anophthalmic socket for an ocular implant. Lesser degrees of injury, such as hyphema, retinal detachments, and corneal lacerations, should be diagnosed and treated before surgical intervention for the correction of frontal sinus injuries. Particular attention should be given to factors that might result in corneal exposure: facial paralysis from a temporal bone injury or other injury to the facial nerve. Lid lacerations should be repaired primarily as early as possible. A complete ophthalmologic examination should be carried out as soon as feasible and visual acuity tests should be performed as soon as the patient is awake and cooperative. Neurologic Injuries Over half of the patients with frontal sinus fractures present with some form of neurologic injury, and these span a wide range.1,7,15,33,38,40 The majority of patients who sustain a frontal sinus fracture will have experienced loss of consciousness. Closed head injury with evidence of cerebral contusion by computed tomography and/or magnetic resonance imaging is very common. Subdural and epidural hematomas requiring immediate neurosurgical intervention occur in 10 percent of patients.1 Open cerebral injuries are seen in the most severe form of frontal sinus fractures and are found in 2.5 to 13 percent of these patients.1,40,41 Depressed skull fractures other than those of the frontal bone are also a common feature in severe motor vehicle–associated frontal sinus fractures.3 A worrisome aspect of frontal sinus fractures is the presence of a cerebrospinal fluid
leak on presentation or on exploration. Up to one-third of patients with frontal sinus fractures will present with a cerebrospinal fluid leak.7,30,38,42 This may be the result of injury to the posterior wall and subsequent disruption of the attached dura and/or the result of a disruption of the anterior cranial fossa floor at the level of the cribriform plate or the fovea ethmoidalis.43 Pneumocephalus is frequently seen on computed tomography in injuries of the frontal sinus. Pneumocephalus is not a reliable or consistent sign for neurologic injury or for the presence of a cerebrospinal fluid leak. Pneumocephalus from injury to the frontal sinus may be caused by involvement of the cribriform, the fovea ethmoidalis, the orbit, or other regions of the skull and/or skull base; thus, it is not a specific or sensitive measure of a potential cerebrospinal fluid leak. In instances of severe frontobasilar injury with or without tissue loss, cerebrospinal fluid leaks are obvious (Fig. 7). Associated Maxillofacial Injuries One-third to one-half of patients with frontal injuries will have associated midface fractures. These fractures lie in close proximity and it is safe to assume that they will involve the nasofrontal duct region, which predisposes to early and late complications. Both medial orbital rim and nasoorbito-ethmoid fractures are associated with a very high involvement of the nasofrontal duct15,32,33 (Fig. 8). This necessitates management of the frontal sinus by obliteration or cranialization.7,32 Medial orbital rim fractures, seen as part of the supraorbital bar involvement in frontal sinus fractures, are seen in up to 20 percent of frontal sinus injuries. With increasing involvement of the nasoethmoid/midface region, progressive collapse/ telescoping of the ethmoid labyrinth is seen. In addition to the obvious implications for orbital reconstruction vis-a`-vis the medial canthal complex, the potential for involvement of the fovea ethmoidalis (the roof of the ethmoid labyrinth) and the cribriform plate increases. Naso-orbitoethmoid fractures are addressed after the frontal sinus is obliterated/cranialized and its fractures reduced in the sequencing of complex craniofacial injuries. With orbital involvement along with frontal sinus injury, the goal is to reconstitute the premorbid orbital volume and achieve the centric position of the globe by proper positioning of the canthal tendons and suspensory ligaments of the globe. This is achieved easier when only one orbit is injured along with the frontal sinus, as the intact side can function as a radiographic template, by
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Plastic and Reconstructive Surgery • December Supplement 2, 2007 based solely on precise reduction of fragments. In either situation and in more extensive, panfacial fractures, correction of frontal sinus fractures assumes greater importance, as this region provides the central stable reduction on which the rest of the craniofacial skeleton may be referenced.
EXAMINATION AND RADIOLOGIC INVESTIGATIONS
Fig. 7. Severe cranio-orbitofrontal injury. The globe is displaced into the maxilla/oral cavity and there is extensive dural exposure and separation of the upper nasal skeleton from the skull base.
Fig. 8. View after reduction of the naso-orbito-ethmoid and frontal region. For the displacement of the bicoronal flap, the superior orbital nerves were downfractured and the bicoronal incision was extended to the tragal/helical junction.
three-dimensional high-resolution computed tomography or through the use of an intraoperative stereolithography template. When both orbits are injured, such reconstruction is more difficult and
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Physical Examination Facial pain is experienced in the majority of conscious patients (82 percent), and over half have frontal lacerations and in a quarter of patients with frontal sinus injury there will be a visible depression.18 Cerebrospinal fluid rhinorrhea or cerebrospinal fluid in the wound is present in up to one-third of these patients.3 The finding of cerebrospinal fluid in conjunction with extensive injury places the patient in a priority for operative intervention. When cerebrospinal fluid leak is present with minimal injury, this presents a diagnostic dilemma. In this circumstance, operative intervention of the frontal sinus is not indicated in the absence of fractures. A cerebrospinal fluid leak under these circumstances should then be investigated radiographically. Suspicion of a cerebrospinal fluid leak can be heightened with a positive halo test. In this test, a drop of the bloody fluid is placed on a cloth surface. If it contains cerebrospinal fluid, this will diffuse in a radial pattern along with the blood. However, the fluid will migrate farther than the blood, forming a “halo” effect. A definite confirmation can be made by sending a specimen for 2-transferrin analysis.44,45 A complete ophthalmologic examination should be carried out as soon as feasible and visual acuity tests should be performed as soon as the patient is awake and cooperative. Any evidence in the drop of visual acuity and/or limitation of extraocular movement should be further investigated by appropriate computed tomographic scanning. The remainder of the craniofacial skeleton should be examined and scanned because of the high incidence of associated craniomaxillofacial injuries. Radiographic Evaluation Plain skull radiographs were used in the past to screen and evaluate for fractures of the frontal sinus, with the Caldwell and lateral views being the most useful. When plain films are available, evidence of air-fluid levels and clouding of the frontal sinus should be investigated further. In most circumstances, plain radiographs should be avoided,
Volume 120, Number 7 Suppl. 2 • Frontal Sinus Fractures because their sensitivity and specificity is very low and are time consuming to obtain, especially in a critically ill patient. However, if a frontal sinus obliteration/cranialization is planned, it is helpful to obtain a 1:1 ratio frontal projection plain radiograph to use as an intraoperative template for entering the frontal sinus. All patients with forehead lacerations and/or palpable deformities in which the magnitude of the injury raises suspicion for a fracture should undergo computed tomographic scanning of the craniofacial skeleton. In those with altered mental status or other evidence of neurologic injury, the evaluation should include a non– contrast-enhanced brain computed tomographic scan to assess for hematomas, contusions, and other brain injuries. In patients with evidence of decrease in visual acuity or loss of color vision, the computed tomographic scan should include the optic foramina, orbital apex, and sella region. Pneumocephalus can be seen on computed tomography with a number of injuries that may or may not involve the frontal sinus. These may involve the cribriform, the fovea ethmoidalis, and the orbit, and thus it is not a specific or sensitive measure of a potential cerebrospinal fluid leak. In the absence of intracranial injury, and with minimal frontal injury that does not merit operative intervention, cerebrospinal fluid leaks are best investigated with high-resolution computed tomographic cisternography and/or nasal endoscopy after the administration of intrathecal fluorescein.
MANAGEMENT OF FRONTAL SINUS FRACTURES Historical Perspective The need to surgically address the frontal sinus arose from infection and the related complications of frontal sinusitis. Complications of frontal sinusitis in the preantibiotic era were fearsome, with high morbidity and mortality secondary to intracranial spread. The first reported procedure on the frontal sinus for a mucopyocele was performed by Wells in 1870.46 Numerous operations of limited extent that involved puncturing the anterior table of the frontal bone were subsequently introduced, some with limited removal of the mucosa and others with packing of the sinus or creation of an external draining sinus tract.46 Reidel first described ablation of the anterior sinus wall in 1898. This was a radical, disfiguring operation that involved removal of the frontal bone and supraorbital bar to the posterior table of the frontal sinus. Few patients could be convinced to un-
dergo this operation, even under the threat of complications with high mortality.46 Killian introduced a variation of this procedure by preserving the supraorbital bar but still removing the anterior table and contents of the frontal sinus and then collapsing the skin to the posterior table of the frontal sinus. The Killian procedure produced less disfigurement but had significant rates of failure because of persistent disease at the nasofrontal ducts and incomplete removal of all frontal sinus mucosa.47 After Skillern published a review of the morbidity and mortality on the Killian procedure, it was abandoned as a treatment option.48 The next significant advance in dealing with frontal sinus infection was the Lynch operation, which relied on exenteration of the anterior ethmoid air cells to create a wide communication from the frontal sinus to the nasal cavity through a medial periorbital incision.49 Disappointing results with this procedure were soon realized because of restenosis of the nasofrontal duct, either by scarring or by herniation of the orbital tissues into the created communication with the nasal cavity.50 –52 Several modifications of this approach using stents of silicone and mucoperiosteal flap were devised in an attempt to maintain this artificial conduit patent. These met with various degrees of success. The osteoplastic flap procedure, as reported by Bergara and Itoiz in 1955, hinged the anterior frontal sinus wall on an inferior pedicle of pericranium.53 This procedure allowed easy visualization of the damaged sinus, replacement of the bone on completion of the surgery, and improved forehead cosmesis. Goodale and Montgomery carried this procedure one step further, as they recognized the importance of nasofrontal duct injury and often removed the sinus contents and obliterated the sinus with autologous fat.51–53 The osteoplastic flap operation has been subsequently modified for use in trauma of the frontal sinus by elevating the pericranium with the scalp flap and exploring the frontal sinus by removal of the free bone fragments. Consistently excellent results with minimal complication rates and a less than 1 percent incidence of infectious complications after mucosal exenteration and fat graft obliteration of sinuses with injured nasofrontal ducts have been reported.15,32,33,43,54,55 A variety of materials such as bone, muscle, fascia, and hydroxyapatite have been successfully used to obliterate the sinus cavity.29,56 –59 Cranialization of the frontal sinus was specifically developed to address severe frontal sinus fractures when the posterior wall is damaged.3,30
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Plastic and Reconstructive Surgery • December Supplement 2, 2007 Classification of Frontal Sinus Procedures and Their Indications Observation The variables that determine which patients can be safely observed, rather than treated by open surgery, are as follows: degree of injury, ability/will to follow-up, availability of expertise in functional endoscopic sinus surgery, and evolution of minimally invasive techniques. Minimally displaced frontal sinus anterior table fractures can be clearly observed. Minimally displaced fractures in the region of the frontonasal duct would traditionally require exploration and management. If there is expertise available to endoscopically open the nasofrontal duct at a later time and the patient is willing and reliable in terms of follow-up, it may be reasonable to observe these patients. These patients will have to be followed on a frequent basis with serial radiographic investigations. Symptoms or findings suggestive of obstruction and/or development of a complication such as a mucocele would be indications for intervention at a later date. The frequency and length of radiographic and clinical follow-up required in these instances has not been defined. Other factors to consider are the need for operative intervention of associated injuries. The following general indications should be considered for frontal sinus surgery in the face of frontal sinus fractures: 1. To avoid immediate and short-term complications such as cerebrospinal fluid leak, meningitis, and spreading infection. 2. To avoid long-term complications such as frontal bone osteomyelitis, chronic frontal sinusitis, mucocele, mucopyocele, and brain abscess. 3. To provide adequate exposure for anatomical reduction of naso-orbito-ethmoid fractures. 4. To restore proper aesthetic contour of the forehead. Applying these indications to the classification system of frontal sinus injury presented in Figure 2 leads to a simplified management algorithm. There are four basic choices for managing the frontal sinus when it is injured: observation, exploration and fracture reduction without obliteration/cranialization, obliteration, and cranialization. Variations in these approaches are related to the methods of soft-tissue access, the type of material used for obliteration, the requirement for bone grafting, whether dural repairs are required, and variations of surgical technique.
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Soft-Tissue Access There are three ways to access the frontal sinus. In limited outer table frontal sinus injuries without involvement of the nasofrontal duct and/or the medial orbital rim, in the absence of other associated regional craniofacial injuries, the fractures can be reduced and fixed through the laceration. In this instance, the sinus mucosa is left intact. Very rarely, in a hypopneumatized frontal sinus with outer table fractures, one can adequately remove the mucosa through an extensive laceration. As a general rule, this should be avoided if possible. Endoscopic repair of frontal sinus fractures has been performed satisfactorily with the use of bone substitutes to recreate the frontal contour.60,61 The approach is similar to that of an endoscopic brow lift. However, the indication for this minimally invasive approach is limited at the present time to nondisplaced outer table fractures that do not involve the medial orbital rim and/or frontonasal duct. This would be a subset of type 1 fractures according to the classification scheme provided here. In addition, the use of bone substitute in the face of acute injury is associated with the risk of secondary infection and should be monitored closely. However, as techniques of endoscopy improve and as the instrumentation for endoscopic surgery becomes increasingly sophisticated, more involved frontal sinus fractures will surely become amenable to treatment with minimally invasive approaches. The accepted method for soft-tissue access to the frontal, nasofrontal, and orbital craniofacial skeletal structures is the bicoronal incision. Though a large incision, the panoramic access it provides is unparalleled and the placement in the hairline completely conceals the incision. Cosmetic problems may arise in the following situations: visibility of incision in subjects with alopecia; injury to the frontal branches of the facial nerve, which will give both a cosmetic and functional problem; and devascularization of the temporal fat pad, with subsequent hollowing of the temporal fossa. Specific sharp dissection under the superficial temporal fascia laterally and under the pericranium medially/centrally will avoid injury to the facial nerve and maximize exposure. In the region of the temporal fat pad, a combination of blunt and sharp dissection to the zygomatic arch is performed, with the goal of minimizing injury to the blood supply of the fat pad. If access to the lateral orbit is required, the bicoronal incision should be extended to the preauricular area to the junction of the tragus and helix of the auricle; this allows better downward displacement of the bicoronal flap (Fig. 8). However, it must be noted that, for isolated access to the zygomatic arch/temporal
Volume 120, Number 7 Suppl. 2 • Frontal Sinus Fractures region, a full bicoronal incision is not required, and this can be achieved through a limited hemicoronal access without extension to the non– hair-bearing skin inferiorly. Meticulous technique with hemostasis and the avoidance of clips at the edges of the flaps will prevent hair loss around the incision.18 It is also important to make the incision of the scalp parallel to the hair follicles. Avoiding the transection of hair follicles further avoids alopecia at the edges of the wound.62,63 At the orbital rim, the superior orbital nerve foramina are outfractured to further facilitate exposure at the nasion and orbits. Exploration and Fracture Reduction Alone without Obliteration or Cranialization Type 1 and some type 2 fractures can be managed with a simple exploration and fracture reduction without the requirement for frontal sinus obliteration. A contraindication for exploration alone is a type 2 fracture that involves the nasoethmoid complex and/or the medial superior orbital rim or orbital floor. These associated injuries will invariably involve the nasofrontal duct, necessitating an obliteration procedure. With obliteration of the frontal sinus, the anterior bone fragments are removed and debrided of mucosal elements and the sinus is irrigated with saline. If there is no evidence of posterior wall injury and nasofrontal duct involvement, reduction in anatomical position with low-profile microplates completes the procedure. If there is evidence of injury to the nasofrontal ducts, the procedure is converted to an obliteration. Frontal Sinus Obliteration Most type 2 fractures that are associated with naso-orbito-ethmoid and superior orbital rim fractures and all type 3 fractures require a frontal sinus obliteration. A bicoronal incision access is required in almost all of these frontal sinus fractures (Fig. 9). Sinus exploration: Frontal bone fragments are removed and debrided of mucosal elements with a high-speed drill and continuous suction irrigation. Mucosal exenteration: All mucosal elements of the frontal sinus must be removed diligently. Attention should be given to the recesses of the frontal sinus. Removal of a layer of bone throughout the sinus will ensure that no mucosal elements are left behind. A high-speed drill with a coarse diamond burr is essential for removal of mucosa, both from the anterior table bone fragments and from the posterior wall. At the edges of the frontal sinus, this becomes technically challenging because of the narrow angle formed where the
Fig. 9. Type 2, simple anterior table displaced fracture.
outer table meets the inner table. It is helpful to use a variety of drill bits with ever-decreasing sizes as this part of the sinus is approached. The direction of drilling in these recesses should be parallel to the posterior wall to avoid injury to the dura. Suction irrigation is essential for this part of the procedure also. The irrigation should be used in a steady flow over where the drill is passed; in this way, the thin film of water flowing over the bone does two important things: it avoids thermal injury to the bone and, most importantly, provides the surgeon with a degree of transparency of the bone. As the bony dissection proceeds in this way, the color of the bone
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Plastic and Reconstructive Surgery • December Supplement 2, 2007 changes as the dura is approached. This is done under the operating microscope or with magnifying loupes. In well-pneumatized sinuses, the bone exposure may need to be increased with the use of additional osteotomies through the anterior frontal table. Rarely, a very-well-pneumatized frontal sinus that extends to the sphenoid wing will require removal of the posterior sinus wall to access the farther recesses by gentle retraction on the frontal lobes. This maneuver converts the obliteration into a cranialization. Nasofrontal duct obliteration: This is necessary for isolation of the frontal sinus from the sinonasal tract to prevent contamination and to avoid regrowth of mucosa from the ethmoids into the frontal sinus. Muscle, fascia, or bone chips can be used to obliterate the nasofrontal ducts bilaterally (Fig. 10). Frontal sinus obliteration: The frontal sinus can be left alone for osteogenesis to occur or obliterated with fat, hydroxyapatite, fascia, or bone chips.56,64 – 67 No significant advantage of one technique over another has been demonstrated. In contaminated fractures, consideration should be given to the use of biomaterials. For example, use of bone substitutes with incomplete removal of mucosa will result in the formation of mucoceles, infection of the material used, and dissolution of the underlying dura.5,68 –70 This can lead to intracranial complications and the loss of tissue of the forehead. Therefore, it is best to avoid nonautogenous materials in the setting of acute injury to avoid serious complications. If there is evidence of
Fig. 10. Superior view of the frontonasal ducts from within the frontal sinus. The superior ethmoid cells have been removed from above to create a zone of injury for scar formation and to prevent mucosal ingrowth. The next step in this sequence will be to plug the ducts with fascia/muscle and/or bone chips. Arrows point to the enlarged region of the frontonasal ducts.
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extensive comminution of the posterior wall, bone fragments must be removed and the dura explored for injury. Dural injuries should be primarily repaired in this instance and the sinus obliterated with fat (Fig. 11). The areas of the nasofrontal ducts (i.e., the floor of the frontal sinus) should be addressed next. The management principle of this area is the creation of scar tissue to the exclusion of mucosal elements in such a fashion that mucosal migration into the obliterated sinus will be prevented. This is done by opening the frontonasal ducts with punch forceps and creating a zone of injury in the superior ethmoid air cells. Care should be taken to avoid injury to the cribriform plate and fovea ethmoidalis. Because the fovea and cribriform are very fragile, the technique of bone removal in the adjacent region should be achieved with a sharp tool or a high-speed drill; avoiding a rocking motion and/or a levering against these structures is critical. The ducts are then tightly packed with muscle or fascia that will provide the nidus for scar formation in this area. Fracture reduction: Frontal sinus fractures are reduced according to standard techniques using microplates. If the comminution is extensive, titanium mesh can be used.8 This technique is particularly useful with the concurrent reduction of orbital rim fractures. The fragments can be reduced in situ or removed and reduced to plates or mesh outside the fracture confines and subsequently positioned to the fracture. Nasoethmoid and orbital fractures must be addressed at this point by fixation onto stable bone in the frontal region. With the dissection
Fig. 11. Dural injury repair with a patch of cadaveric dura and nonabsorbable sutures. The arrow points to the dural repair.
Volume 120, Number 7 Suppl. 2 • Frontal Sinus Fractures proceeding inferiorly, care should be taken to avoid injury to the lacrimal sac. The periosteum is densely adherent to the nasal bones and especially the suture lines. It is important to elevate the soft tissues, including the periosteum, using a sharp elevator. Frontal Sinus Cranialization This procedure was developed specifically for extensive injuries of the frontal sinus that involve cerebrospinal fluid leak on exploration and/or soft-tissue and bone loss such as those seen in type 4 and 5 injuries. The procedure is identical to that of a frontal sinus obliteration, with the exception of complete removal of the posterior sinus wall. It is important in a cranialization procedure to address the recesses of the sinus before removing the posterior wall extensively. This is accomplished with a high-speed diamond drill under continuous-suction irrigation in a pattern similar to that of obliteration. However, the depth of bone removal of the posterior wall is much more extensive. It helps to remove as much bone as possible with the high-speed drill under continuous suction irrigation so as to “eggshell” the posterior table. The dura is then dissected from the overlying bone first in the areas where the posterior table has been fractured. Subsequently, bone fragments are removed with further drilling and/or a rongeur. Care should be taken at the level of the sagittal sinus where the bone invaginates on either side of the sinus. Inferiorly, the crista galli should be drilled carefully with a diamond burr, taking care to avoid entering the cribriform plate. In extensive fractures that involve the cribriform plate and/or the fovea ethmoidalis, fragments of thin bone along with the ethmoid mucosa need to be debrided meticulously. The region of the nasofrontal ducts needs to be managed as in a frontal sinus obliteration. With a cranialization, the correct management of this region is even more critical. Failure to do so will result in mucosal ingrowth directly over dura, potentially exposing the nasal cavity to the splanchnocranium. These principles apply equally to cranialization of the sinus after a bifrontal craniotomy. The residual elements of mucosa, especially those attached to the posterior table, must be removed along with the bone. A pericranial flap can be used to manage extensive injuries of the floor and/or the posterior wall of the frontal sinus. It is frequently a good option for a cerebrospinal fluid leak identified during surgery.13,71–73 This versatile axial pattern fascial flap is an excellent choice when there is a
need to isolate the anterior cranial fossa from the nasal cavity and/or associated paranasal sinuses. The robust blood supply to this flap, when based anteriorly, is from the supratrochlear and supraorbital arteries. The layers included are those of the pericranium and the galea. It can be extended to include a portion of the pericranium and galea distal to the bicoronal incision. In this condition, care is taken when designing the bicoronal incision to preserve the galea at the vertex. Dural repair under these circumstances is achieved with primary closure, a fascial patch, or an artificial dural patch (Fig. 6). A pericranial vascularized flap that can provide blood supply to free calvarial grafts used to reconstruct the frontobasal skeleton should not substitute for primary dural closure. Approximately one in five patients with frontal injuries will require a cranialization.18 The majority of these patients with extensive posterior wall fractures will also have a cerebrospinal fluid leak at exploration. A frontal sinus cranialization is significantly easier when a bicoronal bone flap has been performed for the management of intracranial injury. In this situation, the drilling of the posterior wall can take place ex vivo on the back table, using a high-speed drill. However, in this instance, again the nasofrontal ducts need to be managed in a fashion that will prevent mucosal ingrowth into the splanchnocranium. Frequently, frontal sinus procedures are combined with the repair of additional craniofacial injuries, the most common being orbital and midface fractures.18,62 In the presence of bone loss and in the presence of secondary complications (mucoceles with orbital problems), reconstruction with bone grafts will be required. It is preferable to use split-thickness calvarial bone grafts because they are readily accessible through the bicoronal incision (Figs. 12 and 13). Indications to use split-thickness calvarial bone grafts are as follows63: 1. Extensive loss of support at the skull base over the fovea ethmoidalis and cribriform plate, in combination with a pericranial flap. 2. In superior orbital roof fractures, avoidance of pulsatile exophthalmos and orbital deformity. 3. Extensive bone loss of the anterior table that cannot be replaced with elements of the posterior table. 4. In combination with naso-orbito-ethmoid and orbital reconstruction as layered bone grafts to obliterate the ethmoids and reconstruct the medial orbital wall.
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Plastic and Reconstructive Surgery • December Supplement 2, 2007
Fig. 12. Layered calvarial grafts both superiorly and medially in the orbit after resection of a mucocele.
Fig. 13. Extensive skull fractures associated with both frontal and orbital injuries. The sinus was cranialized both for management and for access for an epidural hematoma evacuation.
Management of Associated Neurosurgical Issues Several issues of importance arise as to the timing of surgical management of neurologic injury in relation to the management of frontal sinus injury. Life-threatening injuries and injuries with the potential for neurologic impairment take precedence over the management of frontal sinus. Evacuation of an intracranial hematoma, whether it is intraparenchymal, subdural, and/or epidural, is performed without delay; the frontal and/or craniofacial injuries may be addressed at a later stage unless they contribute to the neurologic morbidity. It is best in this situation for the patient to declare the course of neurologic progress after neurosurgical intervention before correction of these problems. In the presence of closed head injury, the estimation of intracranial pressure and its impact on neurologic function dictates the timing of surgical repair of frontal injuries. An ex-
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ception to this may be a frontobasilar injury in the presence of markedly raised intracranial pressure that presents with herniation of brain parenchyma into the nasal cavity. In this situation, the splanchnocranium must be isolated from the upper aerodigestive tract through surgical intervention that will most likely concurrently manage the frontal sinus. Severe frontobasilar injuries involving tissue loss, typically seen in industrial accidents, will require correction of dural defects and soft-tissue coverage along with management of the frontal sinus to avoid mucocele formation and ongoing contamination of the cranial cavity by the sinus contents. Bone reconstruction of calvarial defects can be managed at a second stage when the patient is stable neurologically (Fig. 7). If surgical intervention is required emergently for the evacuation of an epidural or subdural hematoma, the frontal sinus could be managed concurrently with the neurologic injury, depending on how stable the patient is and whether further general anesthesia can be tolerated. The easiest method for frontal sinus management in the situation where a bifrontal craniotomy flap has been raised is to cranialize the sinus and obliterate the frontonasal ducts. The presence of radiographic evidence of closed head injury such as multiple small intraparenchymal hematomas may require a period of observation and serial neurologic examinations before surgical intervention for the facial skeletal injuries.
CONTROVERSIAL ISSUE: ENDOSCOPIC MANAGEMENT In recent years, great strides have been made in the endoscopic management of frontal sinus infectious disease.69,70 Advances in instrumentation, including power tools capable of removing the thin bone of the sinuses and endoscopic drills for the removal of more compact bone, have enabled sufficient surgical access of the frontal sinus to deal with most forms of frontal sinusitis.24,70 Furthermore, the use of intraoperative navigation systems has enabled these approaches with an unprecedented degree of safety.70,74 –76 Recently, endoscopic obliteration of the frontal sinus with fat has become possible for infectious disease of the frontal sinus.77 Nevertheless, the management of fractures of the frontal sinus with endoscopic techniques has been limited to contouring of the frontal bone in the simplest of fractures.60 It is possible that in the near future the endoscopic repair of a small subtype of these fractures may be possible. This sub-
Volume 120, Number 7 Suppl. 2 • Frontal Sinus Fractures type of patients will have to have a limited, isolated injury of the frontal sinus outflow without extensive frontal bone fractures and other maxillofacial fractures. In this instance, the goal is to restore the frontal sinus outflow, an indication for which endoscopic techniques are ideally suited. Furthermore, in such an instance, patient follow-up is essential to avoid early and late complications. It is also possible to combine the two endoscopic approaches for restoration of frontal sinus physiologic outflow and contouring of type 1 nondisplaced fractures.
COMPLICATIONS OF FRONTAL SINUS FRACTURES Early Complications A complication is characterized as early if it occurs within the first few weeks of surgical intervention. A number of transient problems can occur after bicoronal access and frontal sinus fracture surgery. Forehead pain, transient anesthesia of the forehead, and transient diplopia should all resolve within 2 to 3 weeks.3,58,78,79 The most frequent significant early complication is a cerebrospinal fluid leak. Depending on the severity of the injuries in the population of patients studied, in some series this is as high as 10 percent.3,40 Cerebrospinal fluid leaks are problematic in the face of intracranial injury. The standard management with a lumbar drain will be contraindicated in the face of intracranial injuries and/or suspected increase in intracranial pressure. Therefore, care must be taken before such a decision is made. The administration of antibiotics for the cerebrospinal fluid leak per se is a controversial subject.80 – 82 Antibiotics should be administered prophylactically for the lumbar drain and if there are independent reasons for their administration. The majority of immediate postoperative cerebrospinal fluid leaks will disappear spontaneously. Reexploration should be considered if a leak persists or it there is a contraindication to conservative management with a lumbar drain. The incidence of meningitis can be as high as 6 percent postoperatively.3 Fatal episodes of meningitis after cranialization procedures has been reported.1 Meningitis is not necessarily associated with an active cerebrospinal fluid leak. As these patients may be neurologically compromised from a head injury, they are uniquely susceptible to the consequences of meningitis. In this situation, the early signs of meningitis such as altered mental status will not become apparent before signs of an infection such as high fever or hypotension. To
minimize the morbidity and potential mortality from meningitis, this condition needs to be diagnosed without delay. Change in mental status, fever, or neck rigidity should prompt an immediate lumbar puncture after a brain computed tomographic scan without any delay. Use of broad-spectrum antibiotics with good cerebrospinal fluid penetration is an essential first step with culturedirected antibiotics following the results of cerebrospinal fluid cultures. The antibiotics should be readjusted appropriately to cerebrospinal fluid cultures. Operative intervention should be postponed in the face of active meningitis. Late Complications Late complications are unusual but insidious and can have significant consequences. A mucocele and/or a mucopyocele can develop as early as a few months or as late as several years after the initial operation.83 Mucoceles cause bone erosion and are capable of involving the sinuses, the orbit, and the splanchnocranium (Fig. 14). Because they are slow growing and produce few symptoms, they are usually discovered late. Reoperation with complete removal of the mucocele and reconstruction to isolate the splanchnocranium from the orbit and nasal cavity is the method of choice for management of mucoceles.84 – 86 Endoscopic marsupialization
Fig. 14. Orbital mucocele as a complication from previous frontal sinus injury.
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Plastic and Reconstructive Surgery • December Supplement 2, 2007 of mucoceles has been attempted after infectious complication of frontal sinusitis, with limited success rates and frequent follow-up requirements87,88 (Fig. 7). Brain abscesses are rare but potentially fatal complications of frontal sinus disease. Spread of low-grade infection from the frontal sinus through the foramina of Breschet by thrombophlebitis brings the infection intracranially.3,28 Brain abscesses develop by spread of infection along the periarteriolar spaces of Virchow, along the arterial supply of the brain parenchyma.89 The symptoms associated with a frontal brain abscess are insidious: loss of appetite, fatigue, lethargy, and subtle changes in personality rather than a fulminant infection. Appropriate neurosurgical intervention without delay is essential in preventing the morbidity and potential mortality, which is high even in the modern antibiotic era. Frontal bone osteomyelitis is a very rare complication. In the preantibiotic era, this was commonly known as Pott’s puffy tumor. Today, this complication is encountered when the frontal sinus has been surgically manipulated on multiple occasions, especially when synthetic material has been used that became infected. This condition requires complete removal of the frontal bone, treatment with antibiotics, and subsequent reconstruction at a later stage. In the past, frontal contour defects were fairly common late complications. This was primarily because of the lack of rigid fixation and subsequent frontal bone loss. However, with the advent of miniplate and microplate fixation and the use of primary bone grafts, this is seen far less frequently. Issues arising from late complications with contouring can be resolved at a later stage with cranial remodeling using mesh and bone substitutes or alloplastic materials. However, the clinician must be absolutely sure that all issues with the frontal sinus are quiescent. It is in this setting that endoscopic repair of contour defects using bone substitutes is effective. It is important to recognize that all patients who have had complications associated with frontal sinus management should be followed long term both clinically and with serial imaging in the early postoperative years. If the frontal sinus was obliterated with fat, magnetic resonance imaging is an excellent modality for follow-up.
SUMMARY Frontal sinus surgery has evolved through the need to address infectious disease of the frontal sinus and its complications. The current manage-
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ment of frontal sinus fractures is based on anatomical and physiologic principles of mucosal function and frontal sinus drainage. Classification schemes based on the severity of frontal sinus injury dictate the type of operative management required. Three general types of operations for frontal sinus fractures have evolved: exploration and fracture reduction alone, frontal sinus obliteration, and frontal sinus cranialization. Evolution of surgical techniques has given these interventions a substantial degree of safety, with minimal complications attributed to the operations themselves. Because of the profile of patients with frontal sinus fractures (i.e., they are unlikely to comply with follow-up), it is prudent to maintain an aggressive approach toward frontal sinus obliteration in the majority of instances. In more extensive injuries, a frontal sinus cranialization is indicated if there is presence of a cerebrospinal fluid leak, tissue, and/or bone loss and extensive associated naso-orbito-ethmoid fractures. Spiros Manolidis, M.D. Department of Otolaryngology– Head and Neck Surgery Columbia University 180 Fort Washington, HP813 New York, N.Y. 10032
[email protected]
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