Frontal Sinus Rescue 26

Contents

Introduction . . . 243

Historical Perspective . . . 244

Technique . . . 244

Indications . . . 246

Introduction Since the late 1980’s, endoscopic frontal sinusotomy has emerged as the preferred technique for the surgi- cal management of chronic frontal sinusitis that is re- fractory to routine medical treatment [9]. During en- doscopic frontal sinusotomy, the partitions of the cells that pneumatize the frontal recess are carefully identified and removed under endoscopic visualiza- tion. Throughout the procedure, mucosa is pre- served, and the boundaries of the frontal recess are not disturbed. Thus, after endoscopic frontal sinusot- omy, the frontal recess should be a widely patent, mu- cosa-lined structure with rigid walls. If a frontal recess boundary is not fixed, then it may collapse into the frontal recess and cause secon- dary frontal recess/ostium stenosis. Today, this most commonly occurs after resection of the middle turbi- nate (which forms the medial boundary of the frontal recess). Because the middle turbinate remnant that remains after middle turbinate resection is often de- stabilized, it may fall laterally and compromise fron- tal recess patency. Simply stated, standard endoscop- ic frontal sinusotomy is often inadequate for the sur- gical treatment of chronic frontal sinusitis after mid- dle turbinate resection, since the technique cannot compensate for frontal recess stenosis due to collapse of the middle turbinate. Revision endoscopic frontal Frontal Sinus Rescue Martin J. Citardi, Pete S. Batra, Frederick A. Kuhn 26 Core Messages

The frontal sinus rescue procedure, more formally known as the revision endoscopic frontal sinusotomy with mucoperiosteal flap advancement, is a technique for the management of frontal sinus obstruction after middle turbinate resection.

In this procedure, the frontal stenosis is removed, and a small mucoperiosteal flap is advanced over the denuded region of the frontal neo-ostium.

In this way, normal frontal mucociliary clearance is restored to the frontal sinus that had been obstructed by previous middle turbinate resection.

The procedure offers several distinct advantages in the setting of frontal recess stenosis related to previous middle turbi- nate resection, including preservation of lateral frontal recess mucosa and less trau- ma to the frontal recess than alternative procedures such as the Modified Lothrop.

Advantages . . . 248

Disadvantages . . . 248

Conclusion . . . 248

References . . . 248

sinusotomy with mucoperiosteal flap advancement, termed the frontal sinus rescue procedure (FSR), has been developed as a modification of the standard en- doscopic frontal sinusotomy technique [5, 10].

The important principles of FSR are:

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FSR is not the creation of a simple hole to drain an obstructed frontal sinus

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In FSR, bony and soft tissue obstruction caused by the destabilized middle turbinate remnant is removed, and then a mucosal flap is advanced across the denuded bone at the medial aspect of the frontal ostium

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Critical lateral frontal recess mucosa is pre- served; thus mucociliary clearance is restored, since the normal drainage pattern is down the lateral aspect of the frontal recess

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Of course, the entire FSR procedure is per- formed under endoscopic visualization.

Historical Perspective

In 1921, Lynch described the external frontoethmoi- dectomy procedure for management of frontal sinus disease [12]. It soon became apparent that frontal re- cess stenosis was the most important cause of failure of frontoethmoidectomy, and the failure rates were unacceptably high. In attempting to minimize this problem, in 1935, Sewall developed a medially-based mucoperiosteal flap, which he used to reline the fron- tal opening [16]. In 1936, McNaught reported a varia- tion on Sewall’s strategy when he introduced a later- ally-based mucoperiosteal flap, which was also used to reline the frontal opening [13]. In 1952, Boyden de- scribed his experience in 57 operations in which he had successfully employed the Sewall procedure [2].

The success of the mucoperiosteal flap for frontal si- nus surgery has also been corroborated by the work of Ogura [14] and Baron [1].

In the 1996–1997, Kuhn developed the FSR, and initial experiences were reported later [5, 10]. FSR builds upon the concepts outlined by Sewall, McNaught, Boyden, and others who were able to use mucoperiosteal flaps to cover denuded areas of a sur-

gically-enlarged frontal neo-ostium. Thus, the im- portance of avoiding exposed bone in the frontal re- cess has been recognized for many decades. Similar- ly, the ability of a mucoperiosteal flap to minimize secondary stenosis is not a new idea.

Technique

Most FSR procedures are performed with intraoper- ative surgical navigation [3, 4]. Review of the preop- erative high-resolution sinus CT at the computer workstation greatly facilitates the comprehension of complex three-dimensional frontal recess anatomy, and this knowledge can be directly applied through intraoperative surgical navigation. Of course, the sur- geon may rely upon CT scan images on a standard x- ray view box; but this approach may be more diffi- cult.

The procedure may be performed under general anesthesia or local anesthesia with intravenous seda- tion. Achieving adequate levels of anesthesia with lo- cal blocks may be problematic; therefore, almost all patients require general anesthesia.

At the beginning of the surgery, detailed endo- scopic examination of the nasal cavity with particu- lar attention to the frontal recess region must be per- formed. Topical 0.05% oxymetazoline provides sig- nificant mucosal decongestion with relatively long duration. Intraoperative surgical navigation may be invaluable during the initial diagnostic nasal endos- copy. Often gentle palpation may help to delineate critical anatomic features. The relationship of the middle turbinate remnant to the medial orbital wall must be established (Fig. 26.1A). In addition, the rela- tive position of the skull base, including the cribri- form plate, should be determined. Because the fron- tal recess is far anterior along the skull base, the 30°, 45°, and 70° telescopes must be used to provide ade- quate visualization. A 0-degree telescope will not provide an adequate view of the area.After this initial examination is complete, the middle turbinate stub and adjacent medial orbital wall should be infiltrated with 1% lidocaine with 1:100,000 epinephrine, which is used for its vasoconstrictive effect. Over-infiltra- tion of local anesthetic will tend to distort the soft- tissue anatomy, and suboptimal infiltration will be associated with greater mucosal oozing.

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The initial step is a parasagittal incision along the most anterior aspect of the middle turbinate stub (Fig. 26.1B). A sickle knife may be passed above the 30°, 45°, or 70° telescope to achieve this objective. Al- ternatively, a frontal recess curette may be used to create a controlled tear, but this approach often in- duces unacceptable collateral tissue damage. Small, through-cutting giraffe forceps, which have just been introduced recently, provide a direct means to create this incision. The parasagittal incision releases the scar band that has pulled the middle turbinate later- ally across the frontal recess outflow track. At this point, the middle turbinate stub should be apparent.

This bony remnant may be directly attached to the skull base, or it may simply be encased in thickened, scarred mucosa. The mucosa along the medial and lateral aspects of the bony middle turbinate remnant is then gently elevated from the underlying bone (Fig. 26.1C). The medial mucosa as well as a very small area of adjacent mucosa along the nasal roof (frontal sinus floor) is removed and discarded (Fig. 26.1D). The lateral mucosal flap is preserved;

this mucosa is the mucoperiosteal flap for which FSR is formally named. After elevation, the mucoperios- teal flap mucosa is gently pushed superiorly so as to avoid inadvertent trauma and damage. Next, the bony middle turbinate stub must be removed (Fig. 26.1E). If it is merely a free fragment, then a non- cutting giraffe forceps may be used to grasp and take it from the operative field. If the bony middle turbi- nate stub is attached to the skull base, then it must be freed of that attachment and removed. Today, the through-cutting frontal giraffe forceps are ideally suited for this function. Alternatively, a frontal recess curette may be used to fracture the middle turbinate stub. Finally, the mucoperiosteal flap, which had been displaced superiorly, is repositioned over the former middle turbinate site (Fig. 26.1F). The raw surface of the underside of the flap faces the denuded bone of the middle turbinate removal site; these two surfaces are likely to stick together throughout the healing process.

In most instances, a frontal recess stent should not be used, since the stent may displace the delicate flap and thus undo what the procedure aims to accom- plish. Of course, in certain instances, a soft, low-cali- ber frontal recess stent will be appropriate.

It must be emphasized that the mucosa of the lat- eral frontal recess is not disturbed. The natural mu-

Fig. 26.1A–F.The fundamental principles of the frontal sinus rescue procedure.AThe middle turbinate remnant (MTR) has scarred across the outflow tract frontal sinus (FS).BThe later- al attachment/adhesion of the middle turbinate remnant has been released.CMucosa from the medial and lateral aspects of the middle turbinate remnant has been partially elevated.

DThe mucosa from the medial aspect of the middle turbinate remnant has been removed and discarded.EThe bony middle turbinate remnant has been resected, and the remaining mu- cosa from its lateral aspect has been preserved. This mucosa, indicated by the arrow, forms the mucoperiosteal flap.FThe mucosal flap has been advanced across the former middle tur- binate attachment point.

cociliary clearance process for the frontal sinus is along the lateral frontal recess; preservation of this mucosa helps to achieve restoration of frontal sinus function.

After FSR, thorough and comprehensive postoper- ative care must be performed [8]. Serial nasal endos- copy provides a simple means for monitoring the frontal neo-ostium as well as a platform for early intervention for the release of early fibrinous adhe- sions. Gentle debridement under endoscopic visual- ization is necessary. Acute suppurative exacerbations of chronic rhinosinusitis may be cultured and appro- priate culture-directed antibiotics should be institut- ed. All patients should perform irrigations with iso- tonic or hypertonic saline solution. Some patients will also receive systemic corticosteroids for a few weeks. (Full discussion of the strategy for postopera- tive care is beyond the scope of this chapter.)

The steps for FSR are schematically illustrated in Fig. 26.1.

Indications

쐽

FSR was designed for the surgical treatment of chronic frontal sinusitis due to frontal recess obstruction after middle turbinate resection.

FSR compensates for the destabilized middle turbi- nate and secondary bony frontal ostium stenosis, while standard endoscopic frontal sinusotomy inade- quately addresses these issues.

Concomitant issues may include frontal sinus/re- cess osteitis/osteoneogenesis, frontal bone osteomye- litis, and mucocele with or without bony erosion.

Since acute infection is associated with greater bleed- ing which may obscure visualization, FSR may not be feasible for the surgical management of acute frontal sinusitis requiring surgical drainage; however, con- sideration for FSR in this scenario may be appropri- ate. In addition, FSR may play a significant role in the surgical management of allergic fungal sinusitis in- volving the frontal sinus after middle turbinate re- section, since FSR creates a patent functional tract that permits long-term endoscopic monitoring and debridement.

In the situation of frontal sinusitis after middle turbinate resection, the central problem is obstruc- tion of the frontal sinus outflow tract by residual bony and soft tissue scar. Both the modified endo- scopic Lothrop procedure and frontal sinus oblitera- tion have been presented as alternatives for surgical management of refractory frontal sinusitis, due to frontal recess/ostium stenosis after middle turbinate amputation. It must be emphasized that both of these procedures carry significant morbidity, and the long- term prognosis after these procedures is often sub- optimal.

Frontal sinus obliteration with autologous fat [6]

may be complicated by perioperative morbidity, chronic pain, and delayed mucocele formation [15].

Furthermore, the evaluation of the frontal sinus in a patient with persistent symptoms after fat oblitera- tion is typically impossible, since MRI signal charac- teristics of the fat graft are inconsistent and mixed, even in the asymptomatic patient [11]. Frontal sinus obliteration focuses on the frontal sinus contents, but the real issue in frontal sinusitis is the frontal recess.

As a result, frontal sinus obliteration is a misdirected procedure that destroys a potentially healthy frontal sinus.

The modified endoscopic Lothrop procedure, a technique for the resection of frontal sinus floor under endoscopic visualization, has gained some popularity [7]. Although this is an endoscopic proce- dure, it is not minimally invasive. The frontal drillout inevitably causes significant frontal recess trauma, including destruction of mucosa, which leads to soft tissue and bony stenosis. The long-term impact of this procedure is unknown. Because frontal recess mucosa is inevitably disrupted by the modified en- doscopic Lothrop procedure, normal frontal muco- ciliary clearance is often irreversibly altered. Thus, even a frontal sinus with a patent frontal neo-ostium after drillout may not clear its mucus appropriately.

FSR should be considered in the context of frontal sinus obliteration and modified endoscopic Lothrop procedure. FSR re-establishes normal frontal si- nus/recess mucociliary clearance, while these other procedures tend to disrupt this physiology. In partic- ular, frontal sinus obliteration destroys the frontal si- nus, and the modified endoscopic Lothrop procedure destroys the frontal recess. FSR seeks to preserve these structures and promote normal sinus function.

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FSR Outcomes

The published surgical results demonstrate that FSR achieves frontal recess patency and function. In a preliminary report, relief from frontal recess scar and frontal ostium stenosis was achieved in 14 of 16 sides (87.5%) in 12 patients with average follow-up of 8.5 months [5]. In an update of the initial publication, Kuhn noted frontal recess patency (confirmed by na- sal endoscopy) and complete resolution of symptoms

in 29 of 32 operative sides in 24 patients [10]. It should be noted that 18 sides were successfully treat- ed with FSR on the first attempt, seven sides required a revision FSR procedure, and four sides required two revision FSR procedures. Mean follow-up was 9.6 months, and one patient had long-term patency at 37 months.

Representative endoscopic images of the healed frontal recess after FSR are shown in Figures 26.2 and 26.3.

Fig. 26.2. AAfter middle turbinate resection, the remnant mid- dle turbinate may scar the frontal recess, leading to formal frontal recess/ostium stenosis. In this endoscopic view of the right frontal recess, the frontal ostium (arrow) is stenotic, and middle turbinate remnant (indicated by *) is simply encased in scar. Purulent secretions drain slowly from the narrowed fron- tal ostium.BThis endoscopic image of the right frontal recess was obtained 8 years after FSR. The frontal neo-ostium is clearly patent and functional. The preoperative view of this frontal recess is shown in A

Fig. 26.3.The FSR mucoperiosteal flap heals across the former insertion point for the destabilized middle turbinate stub. This endoscopic image of the left frontal recess shows a patent left frontal neo-ostium, 7 years after revision FSR. The flap (indi- cated by *) has healed well, and the mucosa is quite healthy

Advantages

FSR offers several distinct advantages:

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Because the lateral frontal recess mucosa is not disturbed by the procedure, mucociliary clearance is restored.

쐽

FSR compensates for both bony and soft tissue stenosis induced by middle turbinate resec- tion.

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FSR builds upon established techniques for endoscopic frontal sinusotomy, and FSR incor- porates mucoperiosteal flaps that were first used as means to re-line surgically created frontal neo-ostia created via an external eth- moidectomy.

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FSR mucoperiosteal flap minimizes the ten- dency for granulation tissue and stenosis.

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FSR is truly minimally invasive; in contrast, the alternative procedure of frontal sinus obliteration is quite extensive with significant morbidity.

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FSR is also a truly functional procedure; in contrast, the alternative procedure of modified endoscopic Lothrop causes significant frontal recess trauma that may ultimately compro- mise the final surgical result.

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Because FSR is not destructive to the frontal recess, surgical revision under endoscopic vis- ualization is reasonably easy to pursue.

Disadvantages

The potential disadvantages of FSR must be consid- ered as well:

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The mucoperiosteal flap, which is the key fea- ture of FSR, is extremely delicate. If the flap is disrupted, the procedure cannot be completed.

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FSR is a difficult technique. The entire proce- dure is performed with curved frontal recess instruments under the visualization provided by the angled telescopes.

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Endoscopic frontal recess instrumentation is required; in particular, fine through-cutting giraffe forceps greatly facilitate the procedure.

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The cribriform plate is just behind the site of the surgical manipulations. Hence, FSR carries the risk of skull-based injury with concomi- tant cerebrospinal fluid leak.

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In some instances, revision FSR will be re- quired.

Conclusion

Frontal sinusitis after middle turbinate resection is a serious surgical challenge, for which standard endo- scopic frontal sinusotomy is poorly suited. The fron- tal sinus rescue procedure, more formally known as revision endoscopic frontal sinusotomy with muco- periosteal flap advancement, is uniquely designed for the correction of frontal stenosis due to middle turbinate resection. In this procedure, the bone and soft-tissue stenosis is removed, and the surgically enlarged frontal neo-ostium is relined with a small mucoperiosteal flap. Mucosa of the lateral frontal re- cess is preserved. In this way, frontal sinus rescue procedure may restore appropriate mucociliary clearance to a frontal sinus obstructed due to previ- ous middle turbinate resection.

References

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