Contents
Introduction . . . . 261
Stenting Materials . . . . 262
Indications for Stenting . . . . 262
External Versus Endoscopic Approach . . . . 263
Duration of Stenting . . . . 265
Postoperative Stent Management . . . . 265
Conclusion . . . . 266
References . . . . 266
Introduction
The concept of frontal sinus stenting to minimize postoperative stenosis and improve mucosalization
of the frontal sinus outflow tract (FSOT) following frontal sinus surgery has been reported in the litera- ture for nearly 100 years. The external fronto-eth- moidectomy, as originally described by Lynch, in- volved postoperative stenting of the nasofrontal communication. Technological advances in sinus en- doscopes, surgical instruments, high-resolution computed tomographic (CT) scanning, and image guidance have allowed for improved visualization and intranasal surgical access to the nasofrontal re- gion. However, despite these advances, postoperative stenosis of the FSOT with recurrent frontal sinus dis- ease remains a significant problem (Fig. 28.1).
Factors such as polyposis, osteitic bone, and later- alization of the middle turbinate/middle turbinate remnant may lead to FSOT stenosis, regardless of the
Frontal Sinus Stenting
Seth J. Kanowitz, Joseph B. Jacobs, Richard A. Lebowitz
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Core Messages
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Postoperative stenting of the frontal sinus outflow tract has been demonstrated to im- prove long-term patency rates
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Soft (Silicone) sheets or stents are superior to rigid stents
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A minimum six-week period of stenting is generally recommended
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Routine care after stent placement includes appropriate antibiotic therapy, nasal irriga- tion, gentle debridement, and topical nasal steroid spray
Fig. 28.1. Endoscopic view of stenotic right frontal sinus neo-
ostium
surgical approach and the adequacy of the frontal sinusotomy. Failure rates of nearly 30% have been re- ported in the literature – and because of this propen- sity for postoperative stenosis of the FSOT, stenting remains an important component in the surgical management of chronic frontal sinusitis.
Stenting Materials
The concept of frontal sinus stenting dates back to 1905 when Ingals reported the use of a gold tube, placed endonasally, to help stent the surgical bed un- til the nasofrontal duct was mucosalized [11]. In 1921, in the initial description of the fronto-ethmoidecto- my procedure that now bears his name, Lynch placed a firm rubber tube in the nasofrontal duct to help maintain patency [14]. The stent remained in place for five days postoperatively. Lynch initially reported a 100% success rate in 15 patients treated with this technique and followed for a period of 2.5 years. Un- fortunately, the long-term failure rate for this proce- dure was found to be approximately 30% [16, 17].
In the 1940’s and 50’s, Goodale, Harris, and Scharfe described their experiences with the use of tantalum for frontal sinus stenting [5, 6, 8, 20]. Originally dis- covered by Eckenberg in 1902, tantalum is an inert basic element. Goodale described the use of a thin sheet of tantalum sutured to the orbital periosteum, while Harris and Scharfe both employed tantalum tubes extending from the frontal sinus into the nose.
In their series, the authors reported success rates that were superior to the classic Lynch operation with de- creased scarring of the nasofrontal duct, improved epithelialization, and decreased granulation tissue formation. Metson employed similar techniques and tantalum foil for drainage of frontal sinus mucoceles, but added an acrylic tube for mucoceles with intra- cranial extension [13]. In 1972, Barton described sim- ilar results in 34 patients implanted with a 6 or 8 mil- limeter (mm) Dacron Woven Arterial Graft sutured into the frontal sinus floor and extending downward into the middle meatus [2]. None of the implants were removed during the 17-year study period, and all of the patients were relieved of their frontal head- ache symptoms.
Initially, most surgeons used rigid frontal sinus stents. However, in animal and clinical trials pub-
lished in 1976, Neel demonstrated the superiority of thin, pliable Silastic sheeting [16, 17]. He reported a 29% failure rate with rubber tubing and a 17% failure rate with thin Silastic sheeting, in patients followed for an average of 13.5 years postoperatively. In his ca- nine model, Neel demonstrated significant fibrosis and osteoblastic activity, with little or no epithelial- ization, in frontal ostia that had been stented with firm rubber stents. In contrast, a normal mucosal lin- ing was observed on histological specimens in ducts stented with thin Silastic sheeting. The difference was felt to be due to local ischemia, impaired drain- age, and infection around the rigid tubes.
Schaefer and Close employed Silastic tubing for small endoscopic frontal sinusotomies (4 to 6 mm) in four of 36 patients treated [19]. However, a 50% sten- osis rate resulted, which was attributed to a failure to maintain a postoperative communication between an air passage and the mucosa, thus resulting in mas- sively hypertrophied mucosa and obstruction of the frontal sinus ostium. More recently, numerous au- thors have described the use of a variety of Silicone tubes, as well as rolled Silicone sheeting, placed ei- ther externally or endoscopically, to help maintain patency of the nasofrontal duct. [1, 3, 4, 7, 9, 10, 12, 15, 18, 21, 22].
Indications for Stenting
There are no standard, accepted indications for post- operative stenting of the FSOT. Routine stenting is not advocated, and the decision to place a frontal si- nus stent is based on the surgeon’s assessment of the patient’s risk for stenosis of the FSOT. A number of conditions need to be considered as risk factors for FSOT stenosis, and thus, as potential indications for stenting.
Hosemann demonstrated a doubling (16% vs.
33%) of the rate of FSOT stenosis when the intraoper- ative diameter of the neo-ostium was less than 5 mm [9]. Therefore, a FSOT diameter of less than 5 mm is often considered an indication for stenting. Other in- dications include extensive demucosalization, partic- ularly with circumferential exposure of bone, at the level of the frontal sinus ostium; osteitic bone (as de- termined by pre-operative CT) in the FSOT; extensive polyposis [as is often seen in patients with allergic
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fungal sinusitis (AFS)]; flail middle turbinate, partic- ularly in cases of partial middle turbinate resection;
and revision frontal sinus surgery with pre-operative scarring or lateralization of the middle turbinate (Fig. 28.2).
Indications for FSOT Stenting
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Frontal sinus neo-ostium diameter less than 5 mm
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Extensive or circumferential exposure of bone in the FSOT
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Polyposis/AFS
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Flail/lateralized middle turbinate
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Revision frontal sinus surgery
External Versus Endoscopic Approach
The initial works of Lynch, Goodale, Harris, and Scharfe predated the availability of fiberoptic nasal endoscopes and endoscopic sinus instrumentation.
Therefore, the techniques of those authors involved an external approach to the frontal sinus and place- ment of the stent. As the surgical management of frontal sinus disease shifts from external to endo- scopic approaches, the techniques of frontal sinus stenting have changed as well.
However, some authors still report the use of an external approach for the placement of a frontal si- nus stent. Barton employed a modified Lynch exter- nal frontal sinusotomy for the placement of a Dacron graft with a reported 100% success rate for relief of frontal headache symptoms [2]. Neel also employed a modified Lynch external approach (Neel-Lake) for
Fig. 28.2.
Intraoperative image
guidance with probe in
stenotic left frontal sinus
outflow tract
the placement of thin Silastic sheeting to stent the frontal ostium. In 13 patients (14 ducts), there was one (7%) short-term failure at four months, which was treated with frontal sinus obliteration. After an addi- tional seven years of observation, the overall failure rate was 20% (three ostia), with both long-term fail- ures being successfully treated with revision frontal sinusotomy [16, 17]. Using a similar external ap- proach in 18 patients who failed a previous transna- sal widening of the nasofrontal communication, Yamasoba placed a Silicone T-tube in the frontal si- nus outflow tract [22]. Complete epithelialization of the nasofrontal communication, and resolution of symptoms was reported in all patients after tube re- moval. Two patients subsequently suffered closure of the FSOT. More recently, Amble placed thin silicone rubber sheeting to reconstruct the nasofrontal com- munication after a modified external Lynch proce- dure in which the frontal process of the superior maxilla was preserved [1]. Of the 164 patients stud- ied, 96% achieved resolution of their symptoms.
In 1990, Schaefer and Close first reported their ex- perience with endoscopic placement of thin Silastic tubing as a frontal sinus stent, resulting in a 50% fail- ure rate in the four patients studied [19] (Fig. 28.3).
Employing three different kinds of stents (Rains self- retaining silicone tube, U-shaped silicone tube, and
H-shaped silicone tube) and various Draf endoscop- ic frontal sinus drainage procedures in 12 patients, Weber reported complete resolution or significant improvement in 10 patients’ frontal sinus symptoms, and moderate improvement in two patients. Howev- er, while clinically significant stenosis of the FSOT did not occur, stenting could not prevent the recur- rence of endoscopically or radiographically visible polypoid mucosal disease [21]. Hoyt reported similar results in 21 patients (32 stents) who had vented tubu- lar plastic stents placed endoscopically [10]. Freeman placed a bi-flanged Silicone tube (Freeman frontal si- nus stent) endoscopically in 55 sinuses and external- ly in nine sinuses with follow-up of 12–45 months [4].
Six sinuses eventually required fat obliteration, four due to restensosis secondary to lateralization of the middle turbinate with scarring, and two due to the development of frontal sinus polyps. Rains also em- ployed a soft Silicone tube with a tapered collapsible bulb placed endoscopically in 67 patients. With a to- tal of 102 stents placed, and follow-up of 8–48 months, a failure rate of 6% was reported. Allergic fungal sinusitis was present in all cases requiring re- vision [18].
Ultimately, the success of all nonobliterative fron- tal sinus surgery, whether external or endoscopic, is judged by the long-term functional patency of the FSOT. In many instances the FSOT may not be visibly patent, but can be endoscopically probed in asymp- tomatic patients [12].
To Pre-operatively Assess the Need for FSOT Stenting
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Carefully review the sinus anatomy on CT to determine the potential surgical diameter of the frontal sinus neo-ostium, as limited by the frontal beak, anterior skull base, medial orbit, and cribiform plate.
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Evaluate the pre-operative CT for radiographic evidence of AFS, and/or osteitis of the bone of the FSOT.
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