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Management of complications of frontal sinus and frontal bone fractures
MANAGEMENT OF COMPLICATIONS OF FRONTAL SINUS AND FRONTAL BONE FRACTURES ROBERT B. STANLEY, JR, MD, DDS
Complications related to untreated and treated fractures of the frontal calvarium, frontal sinus, and anterior skull base are, fortunately, uncommon. However, when they do occur, disturbing alterations in appearance and lifethreatening infections may result, alone or in combination. Extensive reconstructive procedures may be required to restore defects that affect the contour of the forehead or position of the globe. These procedures should not be undertaken until all infection in the frontal and ethmoid sinuses and the frontal bone have been controlled and the chance of recurrent infection in the sinus reduced to a minimum. A rational approach to the management of the injured frontal sinus, based on an understanding of the pathophysiology of drainage system dysfunction, is mandatory for these goals to be achieved. Patients must be made aware that they have a life-long risk of additional problems, even with appropriate management of their initial complications. Copyright 9 1998 by W.B. Saunders Company KEY WORDS: complications, fractures, frontal bone, frontal sinus
Long-term aesthetic and functional complications may arise from both untreated and treated frontal bone fractures that involve the frontal calvarium, frontal sinus, or anterior skull base. Aesthetic complications include irregular forehead contours and inferior displacement of the globe. These occur when the gentle convex contours of the eminence, glabella, supraorbital ridges, orbital roof, and projections of the frontal bone are not correctly restored. Functional complications include progressive pneumocephalus, cerebrospinal fluid rhinorrhea, frontal sinusitis, mucocele-mucopyocele, osteomyelitis, orbital cellulitis or abscess, meningitis, and intracranial abscess. Pneumocephalus and cerebrospinal fluid rhinorrhea are common findings in the posttraumatic and even early postoperative period because of a persistent comminution from the nose or paranasal sinuses through the anterior skull base into the cranial cavity. However, they are typically not seen as long-term complications of fractures of the frontal bone itself, unless the frontal sinus has been cranialized as part of the treatment of an injury that involved the cribiform plate and foveae of the ethmoid sinuses (Fig 1). Long-term functional complications are more likely to be the result of obstructed drainage of mucus from a preserved frontal sinus or an incompletely obliterated sinus. Infection of the inspissated mucus may then spread through the bony walls of the sinus to involve the frontal bone, orbit, or cranial cavity. Although aesthetic complications are usually recognized within 4 to 6 months from the time of
From the Department of Otolaryngology, Head and Neck Surgery, University of Washington School of Medicine, Seattle, WA. Address reprint requests to Robert B. Stanley, Jr, MD, Department of Otolaryngology, Head and Neck Surgery, Harborview Medical Center, Box 359894, 325 9th Ave, Seattle, WA 98104. Copyright 9 1998 by W.B. Saunders Company 1071-0949/98/0504-000258.00/0
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injury or surgery, functional complications may not appear until years later. 1 Therefore, extensive frontal bone reconstructive procedures should not be undertaken unless the possibility of future frontal sinus infections has been eliminated. If infection does occur, ideally it can be treated without the need to dismantle the reconstruction.
FRONTAL SINUS Pathophysiology
The frontal sinus drainage system normally allows the mucus produced by the glands of the ciliated respiratory mucosa lining the sinus to move to and through the frontonasal orifices into the nose. Frontal sinusitis, with or without gross purulence in the sinus, results from intermittent obstruction of the drainage system. A persistent obstruction will lead to formation of a mucocele, which is a mucus-filled cyst that involves the entire sinus. A mucocele slowly expands and may erode through any wall of the sinus, although erosion through the floor of the sinus into the orbit usually occurs first. Headache is the most common symptom of a mucocele. Infection of the mucus creates a mucopyocele and the expansile and erosive processes predominate with increased risk of infectious intraorbital and intracranial complications. Occasionally, the intracranial spread of infection is directly through an area of necrotic bone in the posterior wall of the sinus to produce an extradural empyema, but more often the intracranial bacterial invasion occurs by way of the valueless diploic venous system that connects the vasculature of the sinus mucosa to the intracranial venous system. A septic thrombophlebitis may propagate through the posterior wall to progressively involve the dural venous sinuses, subdural veins, and cerebral veins. 2 Therefore, a subdural abscess or even brain abscess might be the
Operative Techniquesin Plastic and Reconstructive Surgery, Vol 5, No 4 (November), 1998: pp 296-301
Fig 1. (A) Intracranial aerocele that was diagnosed 2 years after attempted cranialization of frontal sinus. (B) Air entered through a supraorbital ethmoid air cell (arrow) that was violated at the time of cranialization. Respiratory mucosa lined the aerocele, adherent to dura. A mucocele is the fluid-filled counterpart of an aerocele.
result of frontal sinus infection without evidence of involvement of the intervening structures. Osteomyelitis of the frontal bone may also occur from the direct extension of infection from the frontal sinus into the surrounding marrow space, or even more rapidly by way of the same valveless diploic venous system. A pericranial abscess, or Pott's puffy tumor, is often associated with frontal bone osteomyelitis. The incidence and natural history of chronic sinusitis, mucocele, mucopyocele, osteomyelitis, and intracranial infection after untreated and treated frontal sinus fractures are unknown. Patients with these complications have been described only as anecdotes in the reviews of frontal sinusitis and frontal sinus fractures. 3-7
Management Acute exacerbations of chronic frontal sinusitis can often be repeatedly managed with success by using antibiotics and decongestants. However, surgical intervention is usually required to rid the patient of persistent or recurrent ~inusitis symptoms, or as part of the management of frontal sinusitis complicated by mucocele-mucopyocele, frontal bone osteomyelitis, or an intraorbital or intracranial infectious process. Nonobliterative surgical techniques, including external frontoethmoidectomy and reconstruction of the frontonasal orifice, are an accepted method for the management of recurrent frontal sinusitis caused by drainage system dysfunction. However, failure rates of 20 FRONTAL SINUS AND FRONTAL BONE FRACTURES
to 30% have been reported with attempts to reconstruct the frontonasal orifice in patients suffering from all forms of inflammatory sinonasal disease. 8 A transnasal endoscopic approach has been advocated by several surgeons for drainage of the frontal sinus, as well as enlargement and cannalization of the obstructed frontonasal orifice. This approach eliminates the need for an external incision and it is thought to increase the chances of lasting patency because of less surgical trauma to the orifice itself. 9 However, the procedure may be technically difficult in the patient with a narrow anteroposterior sinus floor dimension, or distorted anatomy in the area of the frontal recess of the nose because of previous trauma. Regardless of the nonobliterative technique used, creation and prolonged stenting of a large, reconstructed orifice does not guarantee a permanent passage from the frontal sinus into the nose. A correctly obliterated frontal sinus is probably the safest of all possible situations in the patient with chronic drainage system dysfunction following external trauma. 1~ This may be particularly true for the patient who has experienced complicated frontal sinusitis. Suppurative complications can also occur in cases of sinus obliteration, but less frequently than with primary reconstruction of the drainage system. 3,n,~20bliterative procedures will fail if the sinus mucosa is not meticulously removed from the inner walls of every recess of the sinus with cutting burrs, or if mucosal ingrowth occurs from the nose into the sinus 297
through an incompletely sealed frontonasat orifice. Obliteration of an acutely infected sinus carries some risk of infection and loss of the material used to obliterate the sinus, whether it be fascia, fat, or cancellous bone chips. This complication can be avoided if the sinus is externally trephined, drained, and irrigated gently with a salineantibiotic solution through the drainage catheters for the 2 weeks before obliteration. Bilateral trephinations may be required because of the presence of an intersinus septum. Intranasal drainage should be considered by the surgeon who has experience in endoscopic procedures in the frontal recess area of the nose. The obliterative frontal sinus procedure is performed through a coronal incision if the patient does not have a receding hairline. Alternatively, a midforehead incision can be used if it can be camouflaged in a prominent wrinkle line. A poor third choice is a brow incision, which is usually much more visible and carries a higher risk of damage to the supraorbital neurovascular bundles. Traditionally, entrance into the frontal sinus has been an osteoplastic procedure, with maintenance of attachment of the pericranium to the mobilized anterior table of the sinus. 1~ This necessitates extension of the bone cut around the perimeter of the sinus and through both superior orbital rims, followed by an uncontrolled downfracture across the orbital roof/floor of the frontal sinus. This downfracture often makes removal of the mucosa and occlusion of the frontonasal orifices more difficult, possibly increasing the chance of failure. An alternative to the osteoplastic technique is simple removal and reinsertion of the anterior table. The pericranium is elevated over the orbital rims with identification and preservation of the supraorbital neurovascular bundles. The outline of the sinus is confirmed by a review of the axial and coronal computed tomographic scans, fabrication of a template from a preoperative 6-foot Caldwell view radiograph of the frontal sinus, and intraoperative transillumination of the sinus. By using a fine saw, bone
cuts are then placed within the outline of the sinus, including immediately above the superior orbital rims (Fig 2). Beveling of the bone cut is unnecessary because the bone flap will be stabilized with microplates and screws when reinserted. The mucosa must then be removed from all walls of the sinus by using progressively smaller cutting burrs to reach into all recesses and the frontonasal orifices. The orifices and any exposed ethmoid air cells must then be totally excluded from the frontal sinus. This can be accomplished in many cases with muscle/fascial plugs placed into the orifices, but a more dependable seal can be obtained b y using split calvarial bone grafts contoured to fill the orifices and any surrounding defects into the adjacent ethmoid air cells (Fig 2). Then the sinus is obliterated with fat, fascia, or cancellous bone chips, depending on the surgeon's preference. The choice of material seems to be of secondary importance to success compared with the complete removal of mucosa and occlusion of any comminution into the underlying air spaces. The anterior table can be reinserted and stabilized with microplates and screws, or replaced with split calvarial bone grafts if it shows any evidence of ongoing osteitis or has been eroded by a longstanding inflammatory process. Revision of a frontal sinus obliteration that has failed requires identification of the cause of failure, either retained mucosa in the frontal sinus, mucosal ingrowth from the nose or ethmoid sinuses, or granulation tissue in dead space. Infection in an overlooked lateral recess of the frontal sinus can often be treated with a local revision if the recess has been sealed from the obliterated sinus by fibrous tissue or new bone. If the infection involves a large portion of the obliterated sinus, or failure is attributed to an inadequate seal of a frontonasal orifice, the entire obliteration must be revised. The problem with mucosal ingrowth can be even more serious if it occurs in a patient who has undergone a cranialization procedure that removes the posterior table of the sinus and places the frontonasal
Fig 2. Full exposure of the frontal sinus after removal of anterior wall. Supraorbital rims (large arrows) and frontonasal angle are left intact, Mucosa has been removed from the inner surfaces of the sinus and the frontonasal orifices occluded with contoured calvarial bone grafts (small ar-
rows).
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ROBERT B. STANLEY
orifices within the intracranial cavity. Although rare, intracranial mucocele formation is possible (Fig 1). A correction may require a craniotomy with resection and repair of involved dura, in addition to reconstruction of the anterior skull base with bone grafts and a pericranial flap, if still available. A variant of external trauma that may lead to chronic frontal sinusitis is elective craniotomy that enters the frontal sinus. 13 Drainage system obstruction may develop because of a foreign body (bone wax or bone fragments) introduced at the time of craniotomy. Similar problems may arise if methylmethacrylate or silastic is used to reconstruct a frontal bone defect that involves part of a frontal sinus that has not been obliterated. The exposure of the alloplastic material within the sinus is not a problem itself, but any subsequent episode of frontal sinusitis will most likely result in a chronically infected foreign body that must be removed (Fig 3). As with other sequelae related to frontal sinus trauma, this may not occur until months or years later.
FRONTAL BONE A n a t o m i c a l Distortion
Irregular forehead contours can usually be attributed to one or more of the following: (1) failure to recognize a fracture dislocation that will produce a depression in the glabellar or medial supraorbital ridge area when the edema of the overlying soft tissue resolves; (2) poor initial realignment or inadequate stabilization of displaced frag-
ments that may collapse with time across the forehead span, particularly across the anterior wall of the frontal sinus; (3) cicatricial contracture of forehead skin to produce visible outlines of fixation hardware or areas of less than total edge-to-edge contact of bone fragments or grafts (Fig 4); (this often occurs when the overlying skin has been damaged by a laceration or crush-type injury, or the skin thickness has been reduced by elevation of a pericranial or galeofrontalis flap that was used in the repair of a skull base injury); and (4) loss of bone because of frontal sinus ablation, frontal sinusectom~ or craniectomy used as the initial management of the frontal bone or intracranial injuries. Downward displacement of the globe is caused by the failure to restore the contour and level of the orbital projection of the frontal bone. The normal upward convexity of the roof is difficult to duplicate, and a reconstructed roof that seems to be at the correct level often is too flat, thereby pushing the globe inferiorly.14 Management
Restoration of the osseous contours of the frontal bone may be accomplished with alloplastic or autogenous material or a combination of the two. Severe lacerations or the contracture of forehead skin or scalp into large defects may create a lack of well-vascularized, supple soft tissue, which is necessary to accommodate the altered or expanded frontal contours. Tissue expansion in advance of osseous reconstruction may be required to correct this deficit. Ideally, the entire frontal bone, including both orbital rims, is exposed through a coronal incision so that symmetry can be
Fig 3. (A) Right fronto-orbital defect created by removal of infected acrylic cranioplasty that was in contact with remnant of frontal sinus. (B) Reconstruction of frontal and supraorbital c~ontours with split calvarial grafts. Fixation to healthy frontal bone is with 1.0 mm titanium plates and screws. (C) Patient has had no recurrent infections over a 4-year follow-up period.
FRONTAL SINUS AND FRONTALBONE FRACTURES
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supraorbital rims are usually treated with onlay grafts to correct depressions or inlay grafts to correct bone loss. Alloplastic grafts are more contourable into an exact reproduction of anatomic detail, particularly in the area of the superior orbital rims and frontonasal angle, the most technically demanding areas of contour cranioplasty. However, alloplastics should not be used unless the frontal sinus has been previously obliterated and the implant will not be in close proximity to a supraorbital ethmoid air cell. Split cranial bone grafts can be safely placed into these areas but they cannot be contoured as readily as methylmethacrylate. Obliteration of the frontal sinus should also be considered at the time of reconstruction that utilizes bone grafts in any patient who is at risk for future episodes of sinusitis. Removal of the bone grafts might be necessary for management of the infection. An onlay acrylic implant can be fixed to the underlying bone by using microplates and screws or microlag screws. The micro drills used for the screw holes must have drill stops to prevent inadvertent intracranaial intrusion. An inlay acrylic implant can be reinforced with metallic mesh (usually titanium) and the acrylic or mesh can be locked into bony undercuts for stability. Split cranial grafts can also be placed as onlay or inlay grafts and stabilized with microplates and screws or microlag screws (Fig 3). Complex contour defects tend to have a fronto-orbital unit that is distorted in addition to being displaced. This would be expected following trauma that produces fragmentation or actual loss of bone. Segmental osteotomies
Fig 4. Contracture of skin into gap created by craniotome has outlined three-quarters of a frontal bone flap. Plates and screws (arrow) were removed to prevent erosion through thin skin.
evaluated during the reconstruction. The supraorbital neurovascular bundles should be released from their foramina to allow for maximum inferior flap reconstruction. The temporalis muscles should not be detached from the lateral orbital rims or temporal fossa unless the bony defect involves the site of attachment. A muscle that is mobilized must be repositioned and anchored along its normal line of attachment to maintain contour over the temporal fossa. Methylmethacrylate can be used to repair small or large defects with no donor site morbidity. However, it cannot be used in immediate or even close proximity to the nose or paranasal sinuses and it should not be used for at least 1 year from the time of the most recent local or regional infection, is Hydroxyapatite bone cement is an alternative alloplastic material that can be used to fill defects, but the safety of its use in close proximity to the sinuses has not been documented. 16 However, split cranial bone grafts are highly resistant to infection and can be placed into immediate contact with the sinuses and be grafted into a recently infected field as long as the defect margins are free of osteomyelitis. Infected bone must be removed and replaced, which occasionally requires that a craniectomy be performed at the time of the reconstruction to produce a healthy contact point for the bone grafts (Fig 3). Simple contour problems of the forehead, glabella, or 300
Fig 5. (A) Globe dystopia in a patient who had undergone a craniotomy and elevation of depressed frontotemporal skull fracture. (B) Coronal computed tomographic scan shows residual inferior displacement of superior orbital rim and orbital roof. ROBERT B. STANLEY
fractures of the frontal b o n e v a r y f r o m forehead a n d orbit a s y m m e t r y to life-threatening intracranial infections if the frontal sinus is i n v o l v e d b y the injury. Successful m a n a g e m e n t of this w i d e s p e c t r u m of complications requires an u n d e r s t a n d i n g of the p a t h o p h y s i o l o g y that leads to chronic infection within the injured sinus. N o t only m u s t ongoing infection be controlled, b u t also the potential for future acute exacerbations m u s t be eliminated to reduce the chance of infectious complications s p r e a d i n g to adjacent areas. Obliteration of the sinus m a y be necessary to achieve this. Planning for the reconstruction of contour defects of the forehead a n d orbit, w i t h alloplastic material in particular but also with bone, m u s t include consideration of the proximity of the defect to the frontal sinus and the health of the sinus. Creation of a safe sinus is of m o r e initial i m p o r t a n c e than correction of e v e n the m o s t a n n o y i n g aesthetic defect of the frontal bone.
REFERENCES Fig 6. (A) Superior orbital rim has been replaced at correct level and orbital roof reconstructed with a cantilevered split calvarial bone graft (arrow), matching the level of highest point of convexity of normal roof. (B) Globe position has been restored.
usually allow for repositioning of the unit, but m o s t likely inlay a n d onlay b o n e grafts will be n e e d e d to totally reconstruct the unit. The orbital roof m u s t be reconstructed to p r e v e n t or correct d o w n w a r d d i s p l a c e m e n t of the globe b y displaced b o n e f r a g m e n t s or the brain itself (Fig 5). Because of the difficulty with recreating the u p w a r d convexity of the roof, a flat b o n e graft m u s t be cantilevered f r o m the reconstructed frontal bar area at a level approxim a t i n g the highest point of the n o r m a l convexity, not at the reconstructed orbital r i m itself (Fig 6). Direct b o n e - t o - b o n e contact (even along c r a n i o t o m y b o n e cuts) should be reestablished in n o n - h a i r - b e a r i n g areas if possible. Inlay b o n e grafts m a y be necessary to fill g a p s created b y the osteotomies. H y d r o x y a p a t i t e bone cement m a y be u s e d for this if not placed in proximity to the sinuses. A possible contraindication to this type of extensive fronto-orbital reconstruction is the " o n l y seeing eye," w h e r e the possibility of visual loss m u s t be considered.
SUMMARY The frontal b o n e f o r m s the entirety of the u p p e r one-third of the facial skeleton. Its anatomic subunits p r o v i d e the convex contour of the forehead and contribute to the latticelike structure that s u r r o u n d s a n d protects the soft tissue contents of the orbits and cranial cavity. Complications that m a y d e v e l o p related to untreated a n d treated
FRONTAL SINUS AND FRONTAL BONE FRACTURES
1. Bosley WR: Osteoplastic obliteration of the frontal sinus: A review of 100 patients. Laryngoscope 82:1463-1475, 1972 2. Wenig BL, Goldstein MN, Abramson AL: Frontal sinusitis and its intracranial complications. Int J Pediatr Otorhinolaryngol 5:285-302, 1983 3. Wallis A, Donald PJ: Frontal sinus fractures: A review of 72 cases. Laryngoscope 98:593-598, 1988 4. Bordley JE, Farrior JB: Frontal sinus fractures and complications, in English G (ed): Otolaryngology. Philadelphia, PA, Lippincott-Raven, 1989, pp 1-22 5. Donald pJ: The tenacity of the frontal sinus mucosa. Otolaryngol Head Neck Surg 87:557-566, 1979 6. Ioannides CH, Freihofer HP, Friens J: Fractures of the frontal sinus: A rationale of treatment. Br J plast Surg 46:208-214, 1993 7. Lee TT, Ratzker PA, Galarza M, et al: Early combined management of frontal sinus and orbitaland facialfractures. J Trauma 44:665-669, 1998 8. Neel HB, McDonald TJ, Facer GW: Modified Lynch procedure for chronic frontal sinus disease: Rationale, technique, and long-term results. Laryngoscope 97:1274-1279, 1987 9. TerrellJE: Primary sinus surgery, in Cummings CW, Frederickson JM, Harker LA, et al (eds): Otolaryngology: Head and Neck Surgery. St. Louis, MO, CV Mosby, 1998, pp 1145-1172 10. Montgomery WW: Controversies in surgery for chronic frontal sinusitis, in Bailey BJ (ed): Head and Neck Surgery: Otolaryngology. Philadelphia, PA, Lippincott-Raven, 1993, pp 869-881 11. Stanley RB, Schwartz MS: Immediate reconstruction of contaminated central craniofacial injuries with free autogenous grafts. Laryngoscope 99:1011-1015, 1989 12. Wilson BC, Davidson B, Corey JP, et al: Comparison of complications following frontal sinus fractures managed with exploration with or without obliteration over 10 years. Laryngoscope 98:516-520, 1988 13. Schramm VL, Maroon JC: Sinus complications of frontal craniotomy. Laryngoscope 89:1436-1445, 1979 14. Stanley RB: Maxillary and periorbital fractures, in Bailey BJ (ed): Head and Neck Surgery: Otolaryngology.Philadelphia, PA, LippincottRaven, 1999, pp 973-990 15. Crawley WA: Problems and complications in cranioplasty, in Manson PN (ed): Craniomaxillofacial Trauma. Philadelphia, PA, LippincottRaven, 1991, pp 458-465 16. Costantino PD, Friedman CD: Synthetic bone graft substitutes. Otolaryngol Clin North Am 27:1037-1074, 1994
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Complications related to untreated and treated fractures of the frontal calvarium, frontal sinus, and anterior skull base are, fortunately, uncommon. However, when they do occur, disturbing alterations in appearance and lifethreatening infections may result, alone or in combination. Extensive reconstructive procedures may be required to restore defects that affect the contour of the forehead or position of the globe. These procedures should not be undertaken until all infection in the frontal and ethmoid sinuses and the frontal bone have been controlled and the chance of recurrent infection in the sinus reduced to a minimum. A rational approach to the management of the injured frontal sinus, based on an understanding of the pathophysiology of drainage system dysfunction, is mandatory for these goals to be achieved. Patients must be made aware that they have a life-long risk of additional problems, even with appropriate management of their initial complications. Copyright 9 1998 by W.B. Saunders Company KEY WORDS: complications, fractures, frontal bone, frontal sinus
Long-term aesthetic and functional complications may arise from both untreated and treated frontal bone fractures that involve the frontal calvarium, frontal sinus, or anterior skull base. Aesthetic complications include irregular forehead contours and inferior displacement of the globe. These occur when the gentle convex contours of the eminence, glabella, supraorbital ridges, orbital roof, and projections of the frontal bone are not correctly restored. Functional complications include progressive pneumocephalus, cerebrospinal fluid rhinorrhea, frontal sinusitis, mucocele-mucopyocele, osteomyelitis, orbital cellulitis or abscess, meningitis, and intracranial abscess. Pneumocephalus and cerebrospinal fluid rhinorrhea are common findings in the posttraumatic and even early postoperative period because of a persistent comminution from the nose or paranasal sinuses through the anterior skull base into the cranial cavity. However, they are typically not seen as long-term complications of fractures of the frontal bone itself, unless the frontal sinus has been cranialized as part of the treatment of an injury that involved the cribiform plate and foveae of the ethmoid sinuses (Fig 1). Long-term functional complications are more likely to be the result of obstructed drainage of mucus from a preserved frontal sinus or an incompletely obliterated sinus. Infection of the inspissated mucus may then spread through the bony walls of the sinus to involve the frontal bone, orbit, or cranial cavity. Although aesthetic complications are usually recognized within 4 to 6 months from the time of
From the Department of Otolaryngology, Head and Neck Surgery, University of Washington School of Medicine, Seattle, WA. Address reprint requests to Robert B. Stanley, Jr, MD, Department of Otolaryngology, Head and Neck Surgery, Harborview Medical Center, Box 359894, 325 9th Ave, Seattle, WA 98104. Copyright 9 1998 by W.B. Saunders Company 1071-0949/98/0504-000258.00/0
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injury or surgery, functional complications may not appear until years later. 1 Therefore, extensive frontal bone reconstructive procedures should not be undertaken unless the possibility of future frontal sinus infections has been eliminated. If infection does occur, ideally it can be treated without the need to dismantle the reconstruction.
FRONTAL SINUS Pathophysiology
The frontal sinus drainage system normally allows the mucus produced by the glands of the ciliated respiratory mucosa lining the sinus to move to and through the frontonasal orifices into the nose. Frontal sinusitis, with or without gross purulence in the sinus, results from intermittent obstruction of the drainage system. A persistent obstruction will lead to formation of a mucocele, which is a mucus-filled cyst that involves the entire sinus. A mucocele slowly expands and may erode through any wall of the sinus, although erosion through the floor of the sinus into the orbit usually occurs first. Headache is the most common symptom of a mucocele. Infection of the mucus creates a mucopyocele and the expansile and erosive processes predominate with increased risk of infectious intraorbital and intracranial complications. Occasionally, the intracranial spread of infection is directly through an area of necrotic bone in the posterior wall of the sinus to produce an extradural empyema, but more often the intracranial bacterial invasion occurs by way of the valueless diploic venous system that connects the vasculature of the sinus mucosa to the intracranial venous system. A septic thrombophlebitis may propagate through the posterior wall to progressively involve the dural venous sinuses, subdural veins, and cerebral veins. 2 Therefore, a subdural abscess or even brain abscess might be the
Operative Techniquesin Plastic and Reconstructive Surgery, Vol 5, No 4 (November), 1998: pp 296-301
Fig 1. (A) Intracranial aerocele that was diagnosed 2 years after attempted cranialization of frontal sinus. (B) Air entered through a supraorbital ethmoid air cell (arrow) that was violated at the time of cranialization. Respiratory mucosa lined the aerocele, adherent to dura. A mucocele is the fluid-filled counterpart of an aerocele.
result of frontal sinus infection without evidence of involvement of the intervening structures. Osteomyelitis of the frontal bone may also occur from the direct extension of infection from the frontal sinus into the surrounding marrow space, or even more rapidly by way of the same valveless diploic venous system. A pericranial abscess, or Pott's puffy tumor, is often associated with frontal bone osteomyelitis. The incidence and natural history of chronic sinusitis, mucocele, mucopyocele, osteomyelitis, and intracranial infection after untreated and treated frontal sinus fractures are unknown. Patients with these complications have been described only as anecdotes in the reviews of frontal sinusitis and frontal sinus fractures. 3-7
Management Acute exacerbations of chronic frontal sinusitis can often be repeatedly managed with success by using antibiotics and decongestants. However, surgical intervention is usually required to rid the patient of persistent or recurrent ~inusitis symptoms, or as part of the management of frontal sinusitis complicated by mucocele-mucopyocele, frontal bone osteomyelitis, or an intraorbital or intracranial infectious process. Nonobliterative surgical techniques, including external frontoethmoidectomy and reconstruction of the frontonasal orifice, are an accepted method for the management of recurrent frontal sinusitis caused by drainage system dysfunction. However, failure rates of 20 FRONTAL SINUS AND FRONTAL BONE FRACTURES
to 30% have been reported with attempts to reconstruct the frontonasal orifice in patients suffering from all forms of inflammatory sinonasal disease. 8 A transnasal endoscopic approach has been advocated by several surgeons for drainage of the frontal sinus, as well as enlargement and cannalization of the obstructed frontonasal orifice. This approach eliminates the need for an external incision and it is thought to increase the chances of lasting patency because of less surgical trauma to the orifice itself. 9 However, the procedure may be technically difficult in the patient with a narrow anteroposterior sinus floor dimension, or distorted anatomy in the area of the frontal recess of the nose because of previous trauma. Regardless of the nonobliterative technique used, creation and prolonged stenting of a large, reconstructed orifice does not guarantee a permanent passage from the frontal sinus into the nose. A correctly obliterated frontal sinus is probably the safest of all possible situations in the patient with chronic drainage system dysfunction following external trauma. 1~ This may be particularly true for the patient who has experienced complicated frontal sinusitis. Suppurative complications can also occur in cases of sinus obliteration, but less frequently than with primary reconstruction of the drainage system. 3,n,~20bliterative procedures will fail if the sinus mucosa is not meticulously removed from the inner walls of every recess of the sinus with cutting burrs, or if mucosal ingrowth occurs from the nose into the sinus 297
through an incompletely sealed frontonasat orifice. Obliteration of an acutely infected sinus carries some risk of infection and loss of the material used to obliterate the sinus, whether it be fascia, fat, or cancellous bone chips. This complication can be avoided if the sinus is externally trephined, drained, and irrigated gently with a salineantibiotic solution through the drainage catheters for the 2 weeks before obliteration. Bilateral trephinations may be required because of the presence of an intersinus septum. Intranasal drainage should be considered by the surgeon who has experience in endoscopic procedures in the frontal recess area of the nose. The obliterative frontal sinus procedure is performed through a coronal incision if the patient does not have a receding hairline. Alternatively, a midforehead incision can be used if it can be camouflaged in a prominent wrinkle line. A poor third choice is a brow incision, which is usually much more visible and carries a higher risk of damage to the supraorbital neurovascular bundles. Traditionally, entrance into the frontal sinus has been an osteoplastic procedure, with maintenance of attachment of the pericranium to the mobilized anterior table of the sinus. 1~ This necessitates extension of the bone cut around the perimeter of the sinus and through both superior orbital rims, followed by an uncontrolled downfracture across the orbital roof/floor of the frontal sinus. This downfracture often makes removal of the mucosa and occlusion of the frontonasal orifices more difficult, possibly increasing the chance of failure. An alternative to the osteoplastic technique is simple removal and reinsertion of the anterior table. The pericranium is elevated over the orbital rims with identification and preservation of the supraorbital neurovascular bundles. The outline of the sinus is confirmed by a review of the axial and coronal computed tomographic scans, fabrication of a template from a preoperative 6-foot Caldwell view radiograph of the frontal sinus, and intraoperative transillumination of the sinus. By using a fine saw, bone
cuts are then placed within the outline of the sinus, including immediately above the superior orbital rims (Fig 2). Beveling of the bone cut is unnecessary because the bone flap will be stabilized with microplates and screws when reinserted. The mucosa must then be removed from all walls of the sinus by using progressively smaller cutting burrs to reach into all recesses and the frontonasal orifices. The orifices and any exposed ethmoid air cells must then be totally excluded from the frontal sinus. This can be accomplished in many cases with muscle/fascial plugs placed into the orifices, but a more dependable seal can be obtained b y using split calvarial bone grafts contoured to fill the orifices and any surrounding defects into the adjacent ethmoid air cells (Fig 2). Then the sinus is obliterated with fat, fascia, or cancellous bone chips, depending on the surgeon's preference. The choice of material seems to be of secondary importance to success compared with the complete removal of mucosa and occlusion of any comminution into the underlying air spaces. The anterior table can be reinserted and stabilized with microplates and screws, or replaced with split calvarial bone grafts if it shows any evidence of ongoing osteitis or has been eroded by a longstanding inflammatory process. Revision of a frontal sinus obliteration that has failed requires identification of the cause of failure, either retained mucosa in the frontal sinus, mucosal ingrowth from the nose or ethmoid sinuses, or granulation tissue in dead space. Infection in an overlooked lateral recess of the frontal sinus can often be treated with a local revision if the recess has been sealed from the obliterated sinus by fibrous tissue or new bone. If the infection involves a large portion of the obliterated sinus, or failure is attributed to an inadequate seal of a frontonasal orifice, the entire obliteration must be revised. The problem with mucosal ingrowth can be even more serious if it occurs in a patient who has undergone a cranialization procedure that removes the posterior table of the sinus and places the frontonasal
Fig 2. Full exposure of the frontal sinus after removal of anterior wall. Supraorbital rims (large arrows) and frontonasal angle are left intact, Mucosa has been removed from the inner surfaces of the sinus and the frontonasal orifices occluded with contoured calvarial bone grafts (small ar-
rows).
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ROBERT B. STANLEY
orifices within the intracranial cavity. Although rare, intracranial mucocele formation is possible (Fig 1). A correction may require a craniotomy with resection and repair of involved dura, in addition to reconstruction of the anterior skull base with bone grafts and a pericranial flap, if still available. A variant of external trauma that may lead to chronic frontal sinusitis is elective craniotomy that enters the frontal sinus. 13 Drainage system obstruction may develop because of a foreign body (bone wax or bone fragments) introduced at the time of craniotomy. Similar problems may arise if methylmethacrylate or silastic is used to reconstruct a frontal bone defect that involves part of a frontal sinus that has not been obliterated. The exposure of the alloplastic material within the sinus is not a problem itself, but any subsequent episode of frontal sinusitis will most likely result in a chronically infected foreign body that must be removed (Fig 3). As with other sequelae related to frontal sinus trauma, this may not occur until months or years later.
FRONTAL BONE A n a t o m i c a l Distortion
Irregular forehead contours can usually be attributed to one or more of the following: (1) failure to recognize a fracture dislocation that will produce a depression in the glabellar or medial supraorbital ridge area when the edema of the overlying soft tissue resolves; (2) poor initial realignment or inadequate stabilization of displaced frag-
ments that may collapse with time across the forehead span, particularly across the anterior wall of the frontal sinus; (3) cicatricial contracture of forehead skin to produce visible outlines of fixation hardware or areas of less than total edge-to-edge contact of bone fragments or grafts (Fig 4); (this often occurs when the overlying skin has been damaged by a laceration or crush-type injury, or the skin thickness has been reduced by elevation of a pericranial or galeofrontalis flap that was used in the repair of a skull base injury); and (4) loss of bone because of frontal sinus ablation, frontal sinusectom~ or craniectomy used as the initial management of the frontal bone or intracranial injuries. Downward displacement of the globe is caused by the failure to restore the contour and level of the orbital projection of the frontal bone. The normal upward convexity of the roof is difficult to duplicate, and a reconstructed roof that seems to be at the correct level often is too flat, thereby pushing the globe inferiorly.14 Management
Restoration of the osseous contours of the frontal bone may be accomplished with alloplastic or autogenous material or a combination of the two. Severe lacerations or the contracture of forehead skin or scalp into large defects may create a lack of well-vascularized, supple soft tissue, which is necessary to accommodate the altered or expanded frontal contours. Tissue expansion in advance of osseous reconstruction may be required to correct this deficit. Ideally, the entire frontal bone, including both orbital rims, is exposed through a coronal incision so that symmetry can be
Fig 3. (A) Right fronto-orbital defect created by removal of infected acrylic cranioplasty that was in contact with remnant of frontal sinus. (B) Reconstruction of frontal and supraorbital c~ontours with split calvarial grafts. Fixation to healthy frontal bone is with 1.0 mm titanium plates and screws. (C) Patient has had no recurrent infections over a 4-year follow-up period.
FRONTAL SINUS AND FRONTALBONE FRACTURES
299
supraorbital rims are usually treated with onlay grafts to correct depressions or inlay grafts to correct bone loss. Alloplastic grafts are more contourable into an exact reproduction of anatomic detail, particularly in the area of the superior orbital rims and frontonasal angle, the most technically demanding areas of contour cranioplasty. However, alloplastics should not be used unless the frontal sinus has been previously obliterated and the implant will not be in close proximity to a supraorbital ethmoid air cell. Split cranial bone grafts can be safely placed into these areas but they cannot be contoured as readily as methylmethacrylate. Obliteration of the frontal sinus should also be considered at the time of reconstruction that utilizes bone grafts in any patient who is at risk for future episodes of sinusitis. Removal of the bone grafts might be necessary for management of the infection. An onlay acrylic implant can be fixed to the underlying bone by using microplates and screws or microlag screws. The micro drills used for the screw holes must have drill stops to prevent inadvertent intracranaial intrusion. An inlay acrylic implant can be reinforced with metallic mesh (usually titanium) and the acrylic or mesh can be locked into bony undercuts for stability. Split cranial grafts can also be placed as onlay or inlay grafts and stabilized with microplates and screws or microlag screws (Fig 3). Complex contour defects tend to have a fronto-orbital unit that is distorted in addition to being displaced. This would be expected following trauma that produces fragmentation or actual loss of bone. Segmental osteotomies
Fig 4. Contracture of skin into gap created by craniotome has outlined three-quarters of a frontal bone flap. Plates and screws (arrow) were removed to prevent erosion through thin skin.
evaluated during the reconstruction. The supraorbital neurovascular bundles should be released from their foramina to allow for maximum inferior flap reconstruction. The temporalis muscles should not be detached from the lateral orbital rims or temporal fossa unless the bony defect involves the site of attachment. A muscle that is mobilized must be repositioned and anchored along its normal line of attachment to maintain contour over the temporal fossa. Methylmethacrylate can be used to repair small or large defects with no donor site morbidity. However, it cannot be used in immediate or even close proximity to the nose or paranasal sinuses and it should not be used for at least 1 year from the time of the most recent local or regional infection, is Hydroxyapatite bone cement is an alternative alloplastic material that can be used to fill defects, but the safety of its use in close proximity to the sinuses has not been documented. 16 However, split cranial bone grafts are highly resistant to infection and can be placed into immediate contact with the sinuses and be grafted into a recently infected field as long as the defect margins are free of osteomyelitis. Infected bone must be removed and replaced, which occasionally requires that a craniectomy be performed at the time of the reconstruction to produce a healthy contact point for the bone grafts (Fig 3). Simple contour problems of the forehead, glabella, or 300
Fig 5. (A) Globe dystopia in a patient who had undergone a craniotomy and elevation of depressed frontotemporal skull fracture. (B) Coronal computed tomographic scan shows residual inferior displacement of superior orbital rim and orbital roof. ROBERT B. STANLEY
fractures of the frontal b o n e v a r y f r o m forehead a n d orbit a s y m m e t r y to life-threatening intracranial infections if the frontal sinus is i n v o l v e d b y the injury. Successful m a n a g e m e n t of this w i d e s p e c t r u m of complications requires an u n d e r s t a n d i n g of the p a t h o p h y s i o l o g y that leads to chronic infection within the injured sinus. N o t only m u s t ongoing infection be controlled, b u t also the potential for future acute exacerbations m u s t be eliminated to reduce the chance of infectious complications s p r e a d i n g to adjacent areas. Obliteration of the sinus m a y be necessary to achieve this. Planning for the reconstruction of contour defects of the forehead a n d orbit, w i t h alloplastic material in particular but also with bone, m u s t include consideration of the proximity of the defect to the frontal sinus and the health of the sinus. Creation of a safe sinus is of m o r e initial i m p o r t a n c e than correction of e v e n the m o s t a n n o y i n g aesthetic defect of the frontal bone.
REFERENCES Fig 6. (A) Superior orbital rim has been replaced at correct level and orbital roof reconstructed with a cantilevered split calvarial bone graft (arrow), matching the level of highest point of convexity of normal roof. (B) Globe position has been restored.
usually allow for repositioning of the unit, but m o s t likely inlay a n d onlay b o n e grafts will be n e e d e d to totally reconstruct the unit. The orbital roof m u s t be reconstructed to p r e v e n t or correct d o w n w a r d d i s p l a c e m e n t of the globe b y displaced b o n e f r a g m e n t s or the brain itself (Fig 5). Because of the difficulty with recreating the u p w a r d convexity of the roof, a flat b o n e graft m u s t be cantilevered f r o m the reconstructed frontal bar area at a level approxim a t i n g the highest point of the n o r m a l convexity, not at the reconstructed orbital r i m itself (Fig 6). Direct b o n e - t o - b o n e contact (even along c r a n i o t o m y b o n e cuts) should be reestablished in n o n - h a i r - b e a r i n g areas if possible. Inlay b o n e grafts m a y be necessary to fill g a p s created b y the osteotomies. H y d r o x y a p a t i t e bone cement m a y be u s e d for this if not placed in proximity to the sinuses. A possible contraindication to this type of extensive fronto-orbital reconstruction is the " o n l y seeing eye," w h e r e the possibility of visual loss m u s t be considered.
SUMMARY The frontal b o n e f o r m s the entirety of the u p p e r one-third of the facial skeleton. Its anatomic subunits p r o v i d e the convex contour of the forehead and contribute to the latticelike structure that s u r r o u n d s a n d protects the soft tissue contents of the orbits and cranial cavity. Complications that m a y d e v e l o p related to untreated a n d treated
FRONTAL SINUS AND FRONTAL BONE FRACTURES
1. Bosley WR: Osteoplastic obliteration of the frontal sinus: A review of 100 patients. Laryngoscope 82:1463-1475, 1972 2. Wenig BL, Goldstein MN, Abramson AL: Frontal sinusitis and its intracranial complications. Int J Pediatr Otorhinolaryngol 5:285-302, 1983 3. Wallis A, Donald PJ: Frontal sinus fractures: A review of 72 cases. Laryngoscope 98:593-598, 1988 4. Bordley JE, Farrior JB: Frontal sinus fractures and complications, in English G (ed): Otolaryngology. Philadelphia, PA, Lippincott-Raven, 1989, pp 1-22 5. Donald pJ: The tenacity of the frontal sinus mucosa. Otolaryngol Head Neck Surg 87:557-566, 1979 6. Ioannides CH, Freihofer HP, Friens J: Fractures of the frontal sinus: A rationale of treatment. Br J plast Surg 46:208-214, 1993 7. Lee TT, Ratzker PA, Galarza M, et al: Early combined management of frontal sinus and orbitaland facialfractures. J Trauma 44:665-669, 1998 8. Neel HB, McDonald TJ, Facer GW: Modified Lynch procedure for chronic frontal sinus disease: Rationale, technique, and long-term results. Laryngoscope 97:1274-1279, 1987 9. TerrellJE: Primary sinus surgery, in Cummings CW, Frederickson JM, Harker LA, et al (eds): Otolaryngology: Head and Neck Surgery. St. Louis, MO, CV Mosby, 1998, pp 1145-1172 10. Montgomery WW: Controversies in surgery for chronic frontal sinusitis, in Bailey BJ (ed): Head and Neck Surgery: Otolaryngology. Philadelphia, PA, Lippincott-Raven, 1993, pp 869-881 11. Stanley RB, Schwartz MS: Immediate reconstruction of contaminated central craniofacial injuries with free autogenous grafts. Laryngoscope 99:1011-1015, 1989 12. Wilson BC, Davidson B, Corey JP, et al: Comparison of complications following frontal sinus fractures managed with exploration with or without obliteration over 10 years. Laryngoscope 98:516-520, 1988 13. Schramm VL, Maroon JC: Sinus complications of frontal craniotomy. Laryngoscope 89:1436-1445, 1979 14. Stanley RB: Maxillary and periorbital fractures, in Bailey BJ (ed): Head and Neck Surgery: Otolaryngology.Philadelphia, PA, LippincottRaven, 1999, pp 973-990 15. Crawley WA: Problems and complications in cranioplasty, in Manson PN (ed): Craniomaxillofacial Trauma. Philadelphia, PA, LippincottRaven, 1991, pp 458-465 16. Costantino PD, Friedman CD: Synthetic bone graft substitutes. Otolaryngol Clin North Am 27:1037-1074, 1994
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