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Image-guided frontal sinus surgery in children
IMAGE-GUIDED FRONTAL SINUS SURGERY IN CHILDREN SANJAY R. PARIKH, MD, FRCSC, FAAP, SETH M. BROWN, MD, MBA
Surgical management of frontal sinus disease in children is often a challenge, given the wide variation in frontal sinus development. A thorough understanding of the embryology and anatomy of the frontal sinus is essential to safe surgical intervention. With current advances in technology including endoscopy and image guidance, new operative techniques are evolving to safely instrument the pediatric frontal sinus. Here, we review the embryology, anatomy, surgical indications, and contemporary surgical techniques of the frontal sinus in children.
EMBRYOLOGY
ANATOMY
The development of the frontal sinus starts at approximately the third week of gestation with the emergence of the primordial of the nasal cavity.1 Shortly thereafter, olfactory placodes appear in the frontonasal process.1 By the seventh week of fetal life, grooves begin to form on the lateral walls of the primitive olfactory pits.2 Between these grooves, ridges or furrows form, with the superior portion of the first furrow becoming the fetal frontal recess, present as early as 100 days gestation, eventually expanding to occupy the space anterior and lateral to the middle turbinate.3-5 The process of development of the frontal sinus itself is said to start around the age of 1 year and continues into late adolescence.3-4 This occurs by the following methods: direct extension of the recessus frontalis, cellular outgrowths or direct extension of the infundibulum ethmoidale, or from the anterior group of cellulae ethmoidales originating in the frontal furrows.6 Often, a combination of these development processes occurs, making the frontal sinus embryologically an actual extension of an ethmoid air cell that has extended anteriorly and superiorly into the frontal bone.6 In the newborn, the frontal sinus is a bony cell called the frontal cell, which drains to the ethmoidal infundibulum.7 By the age of 2, the fusion of the frontal bones at the metopic suture is usually complete, and it is around this time that a true frontal sinus is said to exist.3,8 At the age of 3, the frontal sinus will usually reach a point above the level of the nasion, which becomes clinically relevant because pathology in the sinus can occur.2,9 The sinus will continue to expand slowly throughout early childhood; by the age of 7, it will have started a phase of rapid extension laterally and medially into the frontal bone.7 One third of children aged 4 to 6 years have a true frontal sinus, and two thirds of children between 6 to 9 years of age have a true frontal sinus. By the age of 6, the frontal sinus has often become radiographically visable.10
The frontal sinus, known as the sinus frontalis, was first described by Volcher Coiter (1534-1576).2 The anatomy of the frontal sinus is extremely variable, ranging from essentially nonexistent to aeration of nearly the entire frontal bone and portions of the sphenoid, parietal, temporal, and maxillary bones.3 Unilateral and total absence of the frontal sinus occurs with good frequency—5% and 4% of the population, respectively.3 Frontal sinus hypoplasia is associated with Apert’s syndrome, Down’s syndrome, Treacher–Collins’ syndrome, and pituitary dwarfism, whereas extensive sinus development can be found with osteogenesis imperfecta tarda, Turner’s syndrome, Klinefelter’s syndrome, and acromegaly.3 On average, however, the adult frontal sinus will obtain a volume of ⬃6 to 7 cc.4,8 Anatomically, the frontal sinus is divided in the midline inferiorly by a thin partition of bone, frequently with multiple dehiscences, known as the intersinus septum.3 This septum often demonstrates wide shifts to one side as it extends superiorly.3 The anterior wall of the sinus is the thickest of all its walls and is composed of both cancellous and compact bone, whereas the thinner posterior table is almost all compact bone.3,4 The frontal sinus drainage pathway, made up of the frontal sinus infundibulum, frontal sinus ostium, and the frontal recess, generally has an hourglass shape and is referred to together as the frontal sinus outflow tract.9 The infundibulum is a cleft in the inferior portion of the frontal sinus that narrows as it extends into the ostium, which is found in the posterior–medial aspect of the sinus floor.3,9 As the pathway continues posterior–inferiorly, it widens as it enters the anterior ethmoid complex. At this point, this closed channel is known as the frontonasal duct, or frontal recess, and appears as a deep anterosuperior depression in the upper surface of the middle meatus.11 The anatomic location of the frontal recess is extremely variable in relation to the ethmoid infundibulum, because this is dependent on the attachment of the superior portion of the uncinate. This superior insertion can be found on the lamina papyracea, skull base, middle turbinate, or any combination of these.12 Most commonly, the uncinate process bends laterally in its most superior portion and inserts on the lamina papyracea, closing the ethmoid infundibulum into a blind pouch known as the terminal recess.12 In this case, the frontal recess will drain between the uncinate and the middle turbinate, medial to the eth-
From the Department of Otolaryngology, Children’s Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, NY. Address reprint requests to Sanjay R. Parikh, MD, Department of Otolaryngology, Children’s Hospital at Montefiore, 3400 Bainbridge Avenue, 3rd Floor, Bronx, NY 10467. E-mail: [email protected] © 2004 Elsevier Inc. All rights reserved. 1043-1810/04/1501-0008$30.00/0 doi:10.1053/j.otot.2004.01.003
OPERATIVE TECHNIQUES IN OTOLARYNGOLOGY—HEAD AND NECK SURGERY, VOL 15, NO 1 (MAR), 2004: PP 37-41
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moid infundibulum. In scenarios where the uncinate attaches to the middle turbinate or skull base, the frontal recess will share a common compartment with the ethmoid infundibulum, and thus exposure of the frontal sinus should occur by removing the superior aspect of the uncinate.12 The majority of the blood supply of the frontal sinus is from branches of the ophthalmic artery, specifically the anterior ethmoidal branch.9 The venous drainage is extremely important because it is often the portal of entry for the spread of sinusitis intracranially. The mucosa of the sinus drains via small diploic veins that extend through the sinus wall and communicates with the venous plexus of the dura, periorbita, and cranial periosteum.13 Specifically, the dural veins empty into the sagittal sinus, communicating directly with the cortical veins draining the brain.14 This intimate extension network of drainage is a setup for the propagation of infection throughout the area.14
FRONTAL SINUSITIS IN CHILDREN The 2 principal etiologic factors in frontal sinusitis are obstruction of the nasofrontal duct and mucosal inflammation.15 It was Van Alyea in the 1940’s who suggested that progression to chronic frontal sinusitis in the presence of a patent ostium is a result of either a blocked middle meatus, often secondary to impingement of the middle turbinate against the lateral nasal wall, or encroachment of the drainage space by an ethmoid or frontal cell.16 A more recent study remarked that 85% of pediatric patients with frontonasal abnormalities demonstrated frontal sinusitis, compared with only a 2% incidence of frontal sinusitis without frontonasal duct abnormality.11 Congenital anatomic considerations include the following: over-pneumatized ethmoid bulla, enlargement of agger nasi cells, large supraorbital ethmoid cells, and variations in insertion of the uncinate process.4 Numerous predisposing factors for frontal sinusitis have been reported in the literature, including allergic and vasomotor rhinitis, mucociliary disorders, immunosuppression, previous sinus surgery, chemical exposure, cocaine abuse, swimming, and previous trauma.17 In one report looking at chronic sinusitis in children, more than half the patients had a positive reaction to allergens on allergy testing.18 The incidence of frontal sinusitis in children is not reported in the recent literature. One study looked at sinus disease in 142 computed tomography (CT) scans of the face performed for other indications and found that 41% had some degree of mucosal thickening of a sinus; however, in the 42 CT scans that visualized the frontal sinus, none showed pathology within this sinus.19 There have been several reports on the microbiology of frontal sinusitis in the literature. One such study compared frontal sinusitis to maxillary sinusitis in similar organisms and found a predominance of S. pneumoniae, H. influenzae, and M. catarrhalis in acute disease and anaerobic bacteria in chronic disease.20 It is hypothesized that the low oxygen tension in the sinus secondary to obstruction supports the growth of anaerobic organisms.4,8,20 Another study reported that H. influenzae was more common in patients undergoing frontal sinus surgery for the first time, whereas coagulase-negative Staphylococcus was more common in patients undergoing revision surgery.21 Independent of the bacteria involved, the concern in frontal sinusitis remains the risk of disease progression.
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COMPLICATIONS OF FRONTAL SINUSITIS Complications from frontal sinusitis generally result from extension to the orbit, the frontal bone itself, or intracranially.10 The frontal sinus is also the most frequent sinus affected by mucoceles, with secondary mucoceles caused by ostia obstruction.22 Orbital complications such as cellulitis, subperiosteal abscess, orbital abscess, and optic neuritis can occur with frontal sinusitis, but they are often presumed secondary to ethmoid disease. Pott’s puffy tumor, first described in 1775 by Percivall Pott, is a subperiosteal abscess of the frontal bone associated with frontal osteomyeleitis.4 Originally described as a complication of trauma, it is now more often observed secondary to frontal sinusitis.8 Intracranial complications from frontal sinusitis include the following: meningitis, epidural abscess, subdural empyema, intracerebral abscess, and dural sinus thrombophlebitis.13 Considering all forms of sinusitis, intracranial complications are the second most common complication, behind only orbital cellulitis.22 Sinusitis has been reported to be the most common source of infection in patients with brain abscesses, and the frontal sinus is the most common sinus affected.13 A retrospective report of 649 patients admitted to a hospital for all forms of sinusitis reported an incidence of 3.7% of intracranial complications, the most common being frontal lobe abscesses.23 The proposed mechanisms of intracranial spread are through direct erosion of frontal bone or anatomic defects, hematogenous spread through septic microemboli, or retrograde progressive extension of thrombophlebitis via the valveless diploic veins of Breschet.4,8,13,14 When intracranial spread has occurred from sinusitis, the morbidity is significant, with average hospitalizations of 1 month and neurological sequelae in 25% of patients.24 It has also been reported that the mortality rate with intracranial spread is between 5% to 10%.13
INDICATIONS FOR SURGERY IN CHILDREN The timing of surgical intervention for pediatric frontal sinusitis is controversial. It is important to note that trends in adult sinusitis usually do not hold true for pediatric patients and that the vast majority of children with sinus infections do not develop chronic problems. Subsequently, surgical treatment of pediatric frontal sinusitis has generally been reserved for disease that has spread beyond the sinus.25 Recent attempts at setting up clinical practice guidelines for pediatric sinusitis have failed because of a lack of consensus on the definition of disease and a method of disease staging.26 It has been mentioned that surgical intervention in children is reasonable after other avenues of disease control have been exhausted. These include adequate courses of antibiotics, adenoidectomy if present, evaluation for immunodeficiency, and control of potential aggravating factors such as smoke exposure and allergic rhinitis.27 Recent literature has also suggested that surgery is often reserved for patients with mucociliary disorders such as cystic fibrosis or Kartagener’s syndrome, or for those with an immunocompromising disorder such as HIV. Talbot reported that only 7 of the last 40 pediatric patients (ie, 15%) undergoing sinus surgery at one institution were new surgical patients without mucociliary or immunologic deficiencies.25 It has been reported that with the exception of mild cases, acute frontal sinusitis should be managed in a hosIMAGE-GUIDED FRONTAL SINUS SURGERY IN CHILDREN
pital setting to prevent complications.28 Some have also suggested that drainage of the sinuses should be performed not only if there is a threat of a complication but also if the sinus fails to drain in 1 to 3 days with medical management.25,28 The situation is more lucid when the disease has already progressed outside of the sinuses, because most would agree then that aggressive surgical treatment is prudent.10,23
PEDIATRIC FRONTAL SINUS SURGERY The ideal operation for frontal sinusitis involves the least invasive operation that addresses the complications associated with the infection, as well as inciting factors that promoted the original disease.4 This is especially true in pediatrics, where the growth of the facial skeleton needs to be considered.25,29 It has been suggested that eliminating disease in the osteomeatal complex will often allow the frontal sinus to drain adequately; thus, it is unusual that instrumentation of the frontal sinus needs to be performed in an initial attempt to clear a diseased frontal sinus.25 As mentioned by Jacobs, the first reported surgical procedure on the frontal sinus was a combined external and intranasal approach published by Wells in 1870.30 Advances in the field have increased the options available to the otolaryngologist; these now include trephination, external frontoethmoidectomy, obliteration with or without an osteoplastic flap, and intranasal endoscopic approaches.31 Trephination was, and in many instances continues to be, the most effective procedure to decompress an infected frontal sinus.10 Advantages to this approach are that it can be performed under local anesthesia, it is relatively simple to perform, and the midline frontal sinus septum can be addressed via an extended approach.10,32 However, this procedure fails to address the structural abnormalities of the frontal sinuses’ normal drainage pathway.32 One further pitfall of trephination is the potential injury to the supratrochlear nerve.33 External frontoethmoidectomy in adults is lauded for good access to the orbit, and it can be useful in cases with orbital complications.13 Several disadvantages of this approach include inadequate exposure in a large or septate sinus and failure to maintain a patent nasofrontal duct,
FIGURE 2. Intraoperative view of the frontal sinus in the saggital plane of a boy with frontal subperiosteal abscess using an infrared image-guidance system. Image-guided confirmation of position was performed before incision and trephination.
resulting in recurrent infections or mucocele formation in 20% to 30% of patients.13 In the pediatric patient, frontoethmoidectomy has been discouraged, given the possibilities of disruption in the growth of the facial skeleton, mucocele formation, and future ductal stenosis.25 Frontal sinus obliteration, used more frequently in the past, is usually only reserved today for persistent disease.10 In children, it has been reported to be used for trauma, recurrent intracranial complications, and destructive osteomyelitis.25 Frontal bone removal is occasionally warranted in cases of osteomyelitis or large areas of bony erosion.8 Endoscopic sinus surgery, in addition to avoiding skin incisions, has the advantage of being able to address other sinus disease through the same approach. This is important because even in cases of isolated frontal sinusitis, middle meatal antrostomies and anterior ethmoidectomies should be performed to open the osteomeatal complex and facilitate intranasal drainage.10 Many surgeons’ reluctance to perform endoscopic sinus surgery in children has been secondary to concern about subsequent altered facial growth and poor visualization secondary to the variable anatomy of the frontal sinus region.32,34-36 The issue of future facial growth was addressed in a recent study of 46 children, where no effect on facial growth was seen after endoscopic sinus surgery of the ethmoid or maxillary sinuses.29 As for visualization of the variable pediatric sinus anatomy, new navigational sinus systems may be helpful in this regard.
PEDIATRIC IMAGE-GUIDED FRONTAL SINUS SURGERY FIGURE 1. Axial plane contrast-enhanced CT scan of an 11year-old male with a frontal subperiosteal abscess secondary to acute frontal sinusitis. The CT scan demonstrates a ring-enhancing midline fluid density over the frontal bone. PARIKH AND BROWN
Image guidance is evolving into a useful adjunct to endoscopic sinus surgery. Image-guidance systems assist the surgeon with navigation of the nares and paranasal sinuses. Intraoperatively, the patient’s relative position to a
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FIGURE 3. Minimally invasive incision over the frontal sinus after image-guided trephination.
specific landmark (eg, headset) is tracked via electromagnetic or infrared communication. This enables a computer to quickly calculate the position of tracked instruments relative to the landmark. This position is then demonstrated on a monitor, with cross-hairs superimposed on multi-planar views of the patient’s CT or magnetic resonance imaging scan.37 Several series have reported favorable outcomes with the use of image guidance for the frontal sinus in adults; however, its full utility in pediatric cases is unclear.38-40
FIGURE 5. Intraoperative view of the nasofrontal recess in the coronal plane of an 11-year-old girl with subdural abscess using an electromagnetic image-guidance system.
Challenges in pediatric frontal sinus surgery consist of variation in frontal sinus growth and limited access in narrow nares. Image guidance can be used in 2 different techniques to address these issues. In the case of a subperiosteal abscess over the frontal sinus (Figure 1), incision and drainage along with frontal sinus trephination is prudent. Image guidance can be useful in pinpointing an exact location for drilling the anterior wall of the frontal sinus and planning an incision (Figure 2). In this manner, a minimally invasive incision can be performed with the knowledge that it is overlying the frontal sinus (Figure 3). This is particularly useful in pediatric patients, given their variable frontal sinus growth. A second technique for which image guidance may be clinically useful is the endoscopic endonasal approach. Frontal sinus instrumentation in children should be avoided except in complicated cases such as an intraorbital or intracranial infection (Figure 4). In these cases, the osteomeatal complex should be opened via maxillary sinusotomy and anterior ethmoidectomy. Subsequently, the nasofrontal recess should be viewed endoscopically and possibly instrumented for release of purulent material. This approach to the frontal sinus is challenging because of the inflamed and hemorrhagic mucosa that occurs in an acute infection. Image guidance can be useful in such cases with navigation, exploration, and instrumentation of the infected nasofrontal recess (Figure 5).
CONCLUSION
FIGURE 4. Axial plane contrast-enhanced CT scan of an 11year-old obtunded female with a subfrontal lobe abscess secondary to frontal sinusitis. The CT scan demonstrates an eliptiform ring-enhancing fluid-filled cavity adjacent to the frontal lobe with contralateral shift of the midline.
40
Frontal sinus surgery in children is rarely performed except in cases of complicated frontal sinusitis. Although traditional surgical approaches to the frontal sinus, such as trephination and external frontoethmoidectomy, continue to be performed, contemporary operative methods include the use of endoscopy and image guidance. Two novel approaches to the pediatric frontal sinus are image-guided IMAGE-GUIDED FRONTAL SINUS SURGERY IN CHILDREN
frontal sinus trephination and image-guided frontal sinusostomy. Our early experience suggests that image guidance may be a useful adjunct to performing frontal sinus surgery in pediatric patients with complicated frontal sinusitis.
REFERENCES 1. Wake M, Takeno S, Hawke M: The early development of sino-nasal mucosa. Laryngoscope 104:850-855, 1994 2. Libersa C, Laude M, Libersa JC: The pneumatization of the accessory cavities of the nasal fossae during growth. Anatomia Clinica 1:265273, 1981 3. Rontal M, Anon JB, Zinreich SJ: Embryology and anatomy of the paranasal sinuses, in Bluestone CD, Stool SE, Alper CM, et al (eds): Pediatric Otolaryngology, vol 2, ed 4. Philadelphia, PA, Saunders, 2003, p 861 4. Deutsch E, Hevron I, Eilon A: Pott’s puffy tumor treated by endoscopic frontal sinusotomy. Rhinology 38:177-180, 2000 5. Sivash E, Sirikei A, Bayazyt YA, et al: Anatomic variations of the paranasal sinus area in pediatric patients with chronic sinusitis. Surg Radiol Anat 24:400-405, 2003 6. Hanson WL: Embryological development of the nasal accessory sinuses. Illinois Med J 60:386-390, 1931 7. Wolf G, Anderhuber W, Kuhn F: Development of the paranasal sinuses in children: Implications for paranasal sinus surgery. Ann Otol Rhinol Laryngol 102:705-711, 1993 8. Bambakidis NC, Cohen AR: Intracranial complications of frontal sinusitis in children: Pott’s puffy tumor revisited. Pediatr Neurosurg 35:82-89, 2001 9. McLaughlin RB, Rehl RM, Lanza DC: Clinically relevant frontal sinus anatomy and physiology. Otolaryngol Clin North Am 34:1-22, 2001 10. Altman KW, Austin MB, Tom LWC, et al: Complications of frontal sinusitis in adolescents: Case presentations and treatment options. Int J Pediatr Otorhinolaryngol 41:9-20, 1997 11. Duvoisin B, Schnyder P: Do abnormalities of the frontonasal duct cause frontal sinusits? A CT study in 198 patients. Am J Roentgenol 159:1295-1298, 1992 12. Friedman M, Landsberg R: Frontal sinus surgery: Endoscopic technique. Op Tech Otolaryngol Head Neck Surg 12:60-65, 2001 13. Lang EE, Curran AJ, Patil N, et al: Intracranial complications of acute frontal sinusitis. Clin Otolaryngol 26:452-457, 2001 14. Remmler D, Boles R: Intracranial complications of frontal sinusitis. Laryngoscope 90:1814-1824, 1980 15. Schenck NL, Rauchbach E, Ogura JH: Frontal sinus disease II. Development of the frontal sinus model: Occlusion of the nasofrontal duct. Laryngoscope 84:1233-1247, 1974 16. Van Alyea OE: Frontal sinus drainage. Ann Otol Rhinol Laryngol 55:267-277, 1946 17. Goldberg AN, Oroszlan G, Anderson TD: Complications of frontal sinusitis and their management. Otolaryngol Clin North Am 34:211225, 2001
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18. Don DM, Yellon RF, Casselbrant ML, et al: Efficacy of a stepwise protocol that includes intravenous antibiotic therapy for the management of chronic sinusitis in children and adolescents. Arch Otolaryngol Head Neck Surg 127:1093-1098, 2001 19. Lesserson JA, Kieserman SP, Finn DG: The radiographic incidence of chronic sinus disease in the pediatric population. Laryngoscope 104: 159-166, 1994 20. Brook I: Bacteriology of acute and chronic frontal sinusitis. Arch Otolaryngol Head Neck Surg 128:583-585, 2002 21. Schlosser RJ, London SD, Gwaltney JM, et al: Microbiology of chronic frontal sinusitis. Laryngoscope 111:1330-1332, 2001 22. Stankiewicz JA, Newell DJ, Park AH: Complications of inflammatory diseases of the sinuses. Otolaryngol Clin North Am 26:639-655, 1993 23. Clayman GL, Adams GL, Paugh DR, et al: Intracranial complications of paranasal sinusitis: A combined institutional review. Laryngoscope 101:234-239, 1991 24. Giannoni CM, Stewart MG, Alford EL: Intracranial complications of sinusitis. Laryngoscope 107:863-867, 1997 25. Talbot AR: Frontal sinus surgery in children. Otolaryngol Clin North Am 1:143-157, 1996 26. Chan KH, Winslow CP, Levin MJ, et al: Clinical practice guidelines for the management of chronic sinusitis in children. Otolaryngol Head Neck Surg 120:328-334, 1999 27. Rosenfeld RM: Pilot study of outcomes in pediatric rhinosinusitis. Arch Otolaryngol Head Neck Surg 121:729-736, 1995 28. Ruoppi P, Seppa J, Nuutinen J: Acute frontal sinusitis: Etiological factors and treatment outcome. Acta Otolaryngol 113:201-205, 1993 29. Bothwell MR, Piccirillo JF, Lusk RP, et al: Long-term outcome of facial growth after functional endoscopic sinus surgery. Otolaryngol Head Neck Surg 126:628-634, 2002 30. Jacobs JB: 100 years of frontal sinus surgery. Laryngoscope 107:S1S36, 1997 (suppl) 31. McLaughlin RB: History of surgical approaches to frontal sinus. Otolaryngol Clin North Am 34:49-57, 2001 32. Suonpaa J, Sipila J, Aitasalo K, et al: Operative treatment of frontal sinusitis. Acta Otolaryngol 529:181-183, 1997 (suppl) 33. Mortimore S, Wormald PJ: Management of acute complicated sinusitis: A 5-year review. Otolaryngol Head Neck Surg 121:639-642, 1999 34. Kuhn FA, Javer AR: Primary endoscopic management of the frontal sinus. Otolaryngol Clin North Am 34:59-75, 2001 35. Wigand ME, Hosemann WG: Endoscopic surgery for frontal sinusitis. Am J Rhinol 5:85-89, 1991 36. Gerber ME, Myer CM, Prenger EC: Transcutaneous frontal sinus trephination with endoscopic visualization of the nasofrontal communication. Am J Otolaryngol 14:55-59, 1993 37. Parikh SR, Fried MP: Navigational systems for sinus surgery: New developments. J Otolaryngol 1:S24-S7, 2003 (suppl) 38. Loehrl TA, Toohill RJ, Smith TL: Use of computer-aided surgery for frontal sinus ventilation. Laryngoscope 110:1962-1967, 2000 39. Metson R: Image-guided sinus surgery: Lessons learned from the first 1000 cases. Otolaryngol Head Neck Surg 128:8-13, 2003 40. Tabaee A, Kacker A, Kassenoff TL, et al: Outcome of computerassisted sinus surgery: a 5-year study. Am J Rhinol 17:291-297, 2003
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Surgical management of frontal sinus disease in children is often a challenge, given the wide variation in frontal sinus development. A thorough understanding of the embryology and anatomy of the frontal sinus is essential to safe surgical intervention. With current advances in technology including endoscopy and image guidance, new operative techniques are evolving to safely instrument the pediatric frontal sinus. Here, we review the embryology, anatomy, surgical indications, and contemporary surgical techniques of the frontal sinus in children.
EMBRYOLOGY
ANATOMY
The development of the frontal sinus starts at approximately the third week of gestation with the emergence of the primordial of the nasal cavity.1 Shortly thereafter, olfactory placodes appear in the frontonasal process.1 By the seventh week of fetal life, grooves begin to form on the lateral walls of the primitive olfactory pits.2 Between these grooves, ridges or furrows form, with the superior portion of the first furrow becoming the fetal frontal recess, present as early as 100 days gestation, eventually expanding to occupy the space anterior and lateral to the middle turbinate.3-5 The process of development of the frontal sinus itself is said to start around the age of 1 year and continues into late adolescence.3-4 This occurs by the following methods: direct extension of the recessus frontalis, cellular outgrowths or direct extension of the infundibulum ethmoidale, or from the anterior group of cellulae ethmoidales originating in the frontal furrows.6 Often, a combination of these development processes occurs, making the frontal sinus embryologically an actual extension of an ethmoid air cell that has extended anteriorly and superiorly into the frontal bone.6 In the newborn, the frontal sinus is a bony cell called the frontal cell, which drains to the ethmoidal infundibulum.7 By the age of 2, the fusion of the frontal bones at the metopic suture is usually complete, and it is around this time that a true frontal sinus is said to exist.3,8 At the age of 3, the frontal sinus will usually reach a point above the level of the nasion, which becomes clinically relevant because pathology in the sinus can occur.2,9 The sinus will continue to expand slowly throughout early childhood; by the age of 7, it will have started a phase of rapid extension laterally and medially into the frontal bone.7 One third of children aged 4 to 6 years have a true frontal sinus, and two thirds of children between 6 to 9 years of age have a true frontal sinus. By the age of 6, the frontal sinus has often become radiographically visable.10
The frontal sinus, known as the sinus frontalis, was first described by Volcher Coiter (1534-1576).2 The anatomy of the frontal sinus is extremely variable, ranging from essentially nonexistent to aeration of nearly the entire frontal bone and portions of the sphenoid, parietal, temporal, and maxillary bones.3 Unilateral and total absence of the frontal sinus occurs with good frequency—5% and 4% of the population, respectively.3 Frontal sinus hypoplasia is associated with Apert’s syndrome, Down’s syndrome, Treacher–Collins’ syndrome, and pituitary dwarfism, whereas extensive sinus development can be found with osteogenesis imperfecta tarda, Turner’s syndrome, Klinefelter’s syndrome, and acromegaly.3 On average, however, the adult frontal sinus will obtain a volume of ⬃6 to 7 cc.4,8 Anatomically, the frontal sinus is divided in the midline inferiorly by a thin partition of bone, frequently with multiple dehiscences, known as the intersinus septum.3 This septum often demonstrates wide shifts to one side as it extends superiorly.3 The anterior wall of the sinus is the thickest of all its walls and is composed of both cancellous and compact bone, whereas the thinner posterior table is almost all compact bone.3,4 The frontal sinus drainage pathway, made up of the frontal sinus infundibulum, frontal sinus ostium, and the frontal recess, generally has an hourglass shape and is referred to together as the frontal sinus outflow tract.9 The infundibulum is a cleft in the inferior portion of the frontal sinus that narrows as it extends into the ostium, which is found in the posterior–medial aspect of the sinus floor.3,9 As the pathway continues posterior–inferiorly, it widens as it enters the anterior ethmoid complex. At this point, this closed channel is known as the frontonasal duct, or frontal recess, and appears as a deep anterosuperior depression in the upper surface of the middle meatus.11 The anatomic location of the frontal recess is extremely variable in relation to the ethmoid infundibulum, because this is dependent on the attachment of the superior portion of the uncinate. This superior insertion can be found on the lamina papyracea, skull base, middle turbinate, or any combination of these.12 Most commonly, the uncinate process bends laterally in its most superior portion and inserts on the lamina papyracea, closing the ethmoid infundibulum into a blind pouch known as the terminal recess.12 In this case, the frontal recess will drain between the uncinate and the middle turbinate, medial to the eth-
From the Department of Otolaryngology, Children’s Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, NY. Address reprint requests to Sanjay R. Parikh, MD, Department of Otolaryngology, Children’s Hospital at Montefiore, 3400 Bainbridge Avenue, 3rd Floor, Bronx, NY 10467. E-mail: [email protected] © 2004 Elsevier Inc. All rights reserved. 1043-1810/04/1501-0008$30.00/0 doi:10.1053/j.otot.2004.01.003
OPERATIVE TECHNIQUES IN OTOLARYNGOLOGY—HEAD AND NECK SURGERY, VOL 15, NO 1 (MAR), 2004: PP 37-41
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moid infundibulum. In scenarios where the uncinate attaches to the middle turbinate or skull base, the frontal recess will share a common compartment with the ethmoid infundibulum, and thus exposure of the frontal sinus should occur by removing the superior aspect of the uncinate.12 The majority of the blood supply of the frontal sinus is from branches of the ophthalmic artery, specifically the anterior ethmoidal branch.9 The venous drainage is extremely important because it is often the portal of entry for the spread of sinusitis intracranially. The mucosa of the sinus drains via small diploic veins that extend through the sinus wall and communicates with the venous plexus of the dura, periorbita, and cranial periosteum.13 Specifically, the dural veins empty into the sagittal sinus, communicating directly with the cortical veins draining the brain.14 This intimate extension network of drainage is a setup for the propagation of infection throughout the area.14
FRONTAL SINUSITIS IN CHILDREN The 2 principal etiologic factors in frontal sinusitis are obstruction of the nasofrontal duct and mucosal inflammation.15 It was Van Alyea in the 1940’s who suggested that progression to chronic frontal sinusitis in the presence of a patent ostium is a result of either a blocked middle meatus, often secondary to impingement of the middle turbinate against the lateral nasal wall, or encroachment of the drainage space by an ethmoid or frontal cell.16 A more recent study remarked that 85% of pediatric patients with frontonasal abnormalities demonstrated frontal sinusitis, compared with only a 2% incidence of frontal sinusitis without frontonasal duct abnormality.11 Congenital anatomic considerations include the following: over-pneumatized ethmoid bulla, enlargement of agger nasi cells, large supraorbital ethmoid cells, and variations in insertion of the uncinate process.4 Numerous predisposing factors for frontal sinusitis have been reported in the literature, including allergic and vasomotor rhinitis, mucociliary disorders, immunosuppression, previous sinus surgery, chemical exposure, cocaine abuse, swimming, and previous trauma.17 In one report looking at chronic sinusitis in children, more than half the patients had a positive reaction to allergens on allergy testing.18 The incidence of frontal sinusitis in children is not reported in the recent literature. One study looked at sinus disease in 142 computed tomography (CT) scans of the face performed for other indications and found that 41% had some degree of mucosal thickening of a sinus; however, in the 42 CT scans that visualized the frontal sinus, none showed pathology within this sinus.19 There have been several reports on the microbiology of frontal sinusitis in the literature. One such study compared frontal sinusitis to maxillary sinusitis in similar organisms and found a predominance of S. pneumoniae, H. influenzae, and M. catarrhalis in acute disease and anaerobic bacteria in chronic disease.20 It is hypothesized that the low oxygen tension in the sinus secondary to obstruction supports the growth of anaerobic organisms.4,8,20 Another study reported that H. influenzae was more common in patients undergoing frontal sinus surgery for the first time, whereas coagulase-negative Staphylococcus was more common in patients undergoing revision surgery.21 Independent of the bacteria involved, the concern in frontal sinusitis remains the risk of disease progression.
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COMPLICATIONS OF FRONTAL SINUSITIS Complications from frontal sinusitis generally result from extension to the orbit, the frontal bone itself, or intracranially.10 The frontal sinus is also the most frequent sinus affected by mucoceles, with secondary mucoceles caused by ostia obstruction.22 Orbital complications such as cellulitis, subperiosteal abscess, orbital abscess, and optic neuritis can occur with frontal sinusitis, but they are often presumed secondary to ethmoid disease. Pott’s puffy tumor, first described in 1775 by Percivall Pott, is a subperiosteal abscess of the frontal bone associated with frontal osteomyeleitis.4 Originally described as a complication of trauma, it is now more often observed secondary to frontal sinusitis.8 Intracranial complications from frontal sinusitis include the following: meningitis, epidural abscess, subdural empyema, intracerebral abscess, and dural sinus thrombophlebitis.13 Considering all forms of sinusitis, intracranial complications are the second most common complication, behind only orbital cellulitis.22 Sinusitis has been reported to be the most common source of infection in patients with brain abscesses, and the frontal sinus is the most common sinus affected.13 A retrospective report of 649 patients admitted to a hospital for all forms of sinusitis reported an incidence of 3.7% of intracranial complications, the most common being frontal lobe abscesses.23 The proposed mechanisms of intracranial spread are through direct erosion of frontal bone or anatomic defects, hematogenous spread through septic microemboli, or retrograde progressive extension of thrombophlebitis via the valveless diploic veins of Breschet.4,8,13,14 When intracranial spread has occurred from sinusitis, the morbidity is significant, with average hospitalizations of 1 month and neurological sequelae in 25% of patients.24 It has also been reported that the mortality rate with intracranial spread is between 5% to 10%.13
INDICATIONS FOR SURGERY IN CHILDREN The timing of surgical intervention for pediatric frontal sinusitis is controversial. It is important to note that trends in adult sinusitis usually do not hold true for pediatric patients and that the vast majority of children with sinus infections do not develop chronic problems. Subsequently, surgical treatment of pediatric frontal sinusitis has generally been reserved for disease that has spread beyond the sinus.25 Recent attempts at setting up clinical practice guidelines for pediatric sinusitis have failed because of a lack of consensus on the definition of disease and a method of disease staging.26 It has been mentioned that surgical intervention in children is reasonable after other avenues of disease control have been exhausted. These include adequate courses of antibiotics, adenoidectomy if present, evaluation for immunodeficiency, and control of potential aggravating factors such as smoke exposure and allergic rhinitis.27 Recent literature has also suggested that surgery is often reserved for patients with mucociliary disorders such as cystic fibrosis or Kartagener’s syndrome, or for those with an immunocompromising disorder such as HIV. Talbot reported that only 7 of the last 40 pediatric patients (ie, 15%) undergoing sinus surgery at one institution were new surgical patients without mucociliary or immunologic deficiencies.25 It has been reported that with the exception of mild cases, acute frontal sinusitis should be managed in a hosIMAGE-GUIDED FRONTAL SINUS SURGERY IN CHILDREN
pital setting to prevent complications.28 Some have also suggested that drainage of the sinuses should be performed not only if there is a threat of a complication but also if the sinus fails to drain in 1 to 3 days with medical management.25,28 The situation is more lucid when the disease has already progressed outside of the sinuses, because most would agree then that aggressive surgical treatment is prudent.10,23
PEDIATRIC FRONTAL SINUS SURGERY The ideal operation for frontal sinusitis involves the least invasive operation that addresses the complications associated with the infection, as well as inciting factors that promoted the original disease.4 This is especially true in pediatrics, where the growth of the facial skeleton needs to be considered.25,29 It has been suggested that eliminating disease in the osteomeatal complex will often allow the frontal sinus to drain adequately; thus, it is unusual that instrumentation of the frontal sinus needs to be performed in an initial attempt to clear a diseased frontal sinus.25 As mentioned by Jacobs, the first reported surgical procedure on the frontal sinus was a combined external and intranasal approach published by Wells in 1870.30 Advances in the field have increased the options available to the otolaryngologist; these now include trephination, external frontoethmoidectomy, obliteration with or without an osteoplastic flap, and intranasal endoscopic approaches.31 Trephination was, and in many instances continues to be, the most effective procedure to decompress an infected frontal sinus.10 Advantages to this approach are that it can be performed under local anesthesia, it is relatively simple to perform, and the midline frontal sinus septum can be addressed via an extended approach.10,32 However, this procedure fails to address the structural abnormalities of the frontal sinuses’ normal drainage pathway.32 One further pitfall of trephination is the potential injury to the supratrochlear nerve.33 External frontoethmoidectomy in adults is lauded for good access to the orbit, and it can be useful in cases with orbital complications.13 Several disadvantages of this approach include inadequate exposure in a large or septate sinus and failure to maintain a patent nasofrontal duct,
FIGURE 2. Intraoperative view of the frontal sinus in the saggital plane of a boy with frontal subperiosteal abscess using an infrared image-guidance system. Image-guided confirmation of position was performed before incision and trephination.
resulting in recurrent infections or mucocele formation in 20% to 30% of patients.13 In the pediatric patient, frontoethmoidectomy has been discouraged, given the possibilities of disruption in the growth of the facial skeleton, mucocele formation, and future ductal stenosis.25 Frontal sinus obliteration, used more frequently in the past, is usually only reserved today for persistent disease.10 In children, it has been reported to be used for trauma, recurrent intracranial complications, and destructive osteomyelitis.25 Frontal bone removal is occasionally warranted in cases of osteomyelitis or large areas of bony erosion.8 Endoscopic sinus surgery, in addition to avoiding skin incisions, has the advantage of being able to address other sinus disease through the same approach. This is important because even in cases of isolated frontal sinusitis, middle meatal antrostomies and anterior ethmoidectomies should be performed to open the osteomeatal complex and facilitate intranasal drainage.10 Many surgeons’ reluctance to perform endoscopic sinus surgery in children has been secondary to concern about subsequent altered facial growth and poor visualization secondary to the variable anatomy of the frontal sinus region.32,34-36 The issue of future facial growth was addressed in a recent study of 46 children, where no effect on facial growth was seen after endoscopic sinus surgery of the ethmoid or maxillary sinuses.29 As for visualization of the variable pediatric sinus anatomy, new navigational sinus systems may be helpful in this regard.
PEDIATRIC IMAGE-GUIDED FRONTAL SINUS SURGERY FIGURE 1. Axial plane contrast-enhanced CT scan of an 11year-old male with a frontal subperiosteal abscess secondary to acute frontal sinusitis. The CT scan demonstrates a ring-enhancing midline fluid density over the frontal bone. PARIKH AND BROWN
Image guidance is evolving into a useful adjunct to endoscopic sinus surgery. Image-guidance systems assist the surgeon with navigation of the nares and paranasal sinuses. Intraoperatively, the patient’s relative position to a
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FIGURE 3. Minimally invasive incision over the frontal sinus after image-guided trephination.
specific landmark (eg, headset) is tracked via electromagnetic or infrared communication. This enables a computer to quickly calculate the position of tracked instruments relative to the landmark. This position is then demonstrated on a monitor, with cross-hairs superimposed on multi-planar views of the patient’s CT or magnetic resonance imaging scan.37 Several series have reported favorable outcomes with the use of image guidance for the frontal sinus in adults; however, its full utility in pediatric cases is unclear.38-40
FIGURE 5. Intraoperative view of the nasofrontal recess in the coronal plane of an 11-year-old girl with subdural abscess using an electromagnetic image-guidance system.
Challenges in pediatric frontal sinus surgery consist of variation in frontal sinus growth and limited access in narrow nares. Image guidance can be used in 2 different techniques to address these issues. In the case of a subperiosteal abscess over the frontal sinus (Figure 1), incision and drainage along with frontal sinus trephination is prudent. Image guidance can be useful in pinpointing an exact location for drilling the anterior wall of the frontal sinus and planning an incision (Figure 2). In this manner, a minimally invasive incision can be performed with the knowledge that it is overlying the frontal sinus (Figure 3). This is particularly useful in pediatric patients, given their variable frontal sinus growth. A second technique for which image guidance may be clinically useful is the endoscopic endonasal approach. Frontal sinus instrumentation in children should be avoided except in complicated cases such as an intraorbital or intracranial infection (Figure 4). In these cases, the osteomeatal complex should be opened via maxillary sinusotomy and anterior ethmoidectomy. Subsequently, the nasofrontal recess should be viewed endoscopically and possibly instrumented for release of purulent material. This approach to the frontal sinus is challenging because of the inflamed and hemorrhagic mucosa that occurs in an acute infection. Image guidance can be useful in such cases with navigation, exploration, and instrumentation of the infected nasofrontal recess (Figure 5).
CONCLUSION
FIGURE 4. Axial plane contrast-enhanced CT scan of an 11year-old obtunded female with a subfrontal lobe abscess secondary to frontal sinusitis. The CT scan demonstrates an eliptiform ring-enhancing fluid-filled cavity adjacent to the frontal lobe with contralateral shift of the midline.
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Frontal sinus surgery in children is rarely performed except in cases of complicated frontal sinusitis. Although traditional surgical approaches to the frontal sinus, such as trephination and external frontoethmoidectomy, continue to be performed, contemporary operative methods include the use of endoscopy and image guidance. Two novel approaches to the pediatric frontal sinus are image-guided IMAGE-GUIDED FRONTAL SINUS SURGERY IN CHILDREN
frontal sinus trephination and image-guided frontal sinusostomy. Our early experience suggests that image guidance may be a useful adjunct to performing frontal sinus surgery in pediatric patients with complicated frontal sinusitis.
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