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 (Metzinger, 2005). 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 (May, 1970). 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 (Harris, 1987).
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 (Johnson, 1984; Schatz, 1984; Harris, 1987) 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 (Harris, 1987). The nasofrontal duct complex should be evaluated in both the axial and coronal planes.
History of the Procedure
The progression of frontal sinus surgery stems from the first ablative procedure described by Reidel in 1898. 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.
In 1921, Lynch described the first frontoethmoidectomy, leaving the anterior table intact but completely removing the ethmoid sinuses and the frontal sinus floor. An indwelling catheter was inserted for prolonged drainage.
In 1951, Bergara and Itoiz devised the osteoplastic flap procedure. 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. 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 (May, 1970). 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 (May, 1970; Levine, 1986). 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. 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.
Problem
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 (May, 1970). Displacement of the anterior table can also lead to depression of the forehead and a cosmetic deformity (see Images 1-2).
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 (Bordley, 1973). 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 Images 3-4). 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.
Frequency
Frontal sinus fractures comprise 5-12% of maxillofacial traumas (May, 1970; McGraw-Wall, 1998; Gerbino, 2000). The incidence appears to be approximately 9 cases per 100,000 adults (Wright, 1992).
Etiology
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 (Shockley, 1988; Wright, 1992; Gerbino, 2000; Yavuzer, 2005). 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 (Rohrich, 1992).
Pathophysiology
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 (Nahum, 1975).
Clinical
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 (Rohrich, 1992; Wright, 1992; Yavuzer, 2005). As many as 93% of patients present with multiple associated facial fractures, skull fractures, or both (Rohrich, 1992; Wright, 1992). In one series, 20% of patients presented with CSF rhinorrhea (Yavuzer, 2005).
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 (Harris, 1987). 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 (Levine, 1986). 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.
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