Frontal Sinus Stenting Techniques Periprocedural Care

The frontal recess is difficult to access endoscopically without the use of specialized equipment designed to navigate its complex anatomy. This equipment includes curved suctions, angled endoscopes (30º, 45º, and 70º), frontal giraffe instruments (various angles, lengths, and types), a frontal sinus seeker, and image guidance system. Many stents of different shapes and materials are commercially available. Some surgeons prefer to fashion their own stents with various materials (see the image below).

Examples of frontal sinus stents: (A) Sheet of 1/100-inch thick silastic fashioned into a T-shaped stent, (B) reinforced silastic sheet used for Draf 3 cavity, (C) Rains silastic stent, (D) Silastic T-tube stent, (E) Acclarent Relieva Stratus MicroFlow Spacer, (F) Intersect ENT Propel sinus implant (FDA approved for use in the ethmoid sinus; use in the frontal sinus as a stent is off-label).

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Historically, different materials have been used to construct stents. These include gold, tantalum foil, polyethylene terephthalate (Dacron), and polymeric silicone (Silastic). ^[9] One of the most influential studies directing the design of stents was that of Neel et al, in which the superiority of soft versus rigid stents was demonstrated based on outcomes in a dog model. They found that the use of firm tubing hampered epithelialization and stimulated osteoblastic activity and scar formation. ^[13] This was thought to be due to local ischemia, impaired drainage, and infection around the rigid tubes.

Since this landmark study, various soft stenting materials have been introduced (see the image below).

Examples of frontal sinus stents: (A) Sheet of 1/100-inch thick silastic fashioned into a T-shaped stent, (B) reinforced silastic sheet used for Draf 3 cavity, (C) Rains silastic stent, (D) Silastic T-tube stent, (E) Acclarent Relieva Stratus MicroFlow Spacer, (F) Intersect ENT Propel sinus implant (FDA approved for use in the ethmoid sinus; use in the frontal sinus as a stent is off-label).

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These include rolled silicone sheeting, silicone tubing, soft catheter devices, Merocel spacers, soft rubber T-tubes, and numerous proprietary devices, such as the Rains self-retaining stent with a tapered collapsible bulb at the distal end (see the image below), ^[7] Freeman bi-flanged silicone stent, ^[14] Jacobs radiopaque silicone frontal sinus cannula, and Parrell frontal sinus T-stent. U-shaped or H-shaped stents can be used for bilateral frontal sinus stenting in Draf III or endoscopic Lothrop procedures. ^[15] Other variations include biliary-type or specially designed T-tubes that can be used when the frontal intersinus septum is taken down. ^[5]

Endoscopic placement of right frontal sinus stent after a revision Draf 2b frontal ostioplasty in a patient with previous surgery and radiation for esthesioneuroblastoma. (A) 1/100 thick silastic sheet is cut into a T shape based on the size of the frontal ostium, (B) right frontal ostium; view with a 70º endoscope, (C) the sheet is to be rolled into a stent, grasped with giraffe forceps, and the T flange inserted into the frontal sinus, (D) the rolled part of the stent lines the area of the frontal recess.

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Stent modifications include the use of radiopaque markers, expandable elements, winged flanges for self-retention, as well as suture tails to facilitate easy removal in the office setting. More recently, experimentation with drug-eluting stent materials (see Medications section) has occurred. Hosemann et al presented one of the first drug-releasing stents in 2002, which was capable of releasing dexamethasone for a period of at least 25 days. ^[16] Dexamethasone-releasing stents were shown to decrease granulation formation and stroma thickness without impeding epithelial differentiation when compared to placebo in rabbit sinusotomies. ^[17]

Herrmann and colleagues showed paclitaxel-impregnated stents were well tolerated in a sheep model and hypothesized this local drug delivery method may minimize postoperative scarring. ^[18] Doxycycline-releasing stents were subsequently introduced by Huvenne et al who demonstrated suppressed bacterial growth and improved visual analog scale for the frontal region at 3 months when compared with placebo. ^[19] The AcclarentRelieva Stratus MicroFlow Spacer designed with a microporous reservoir for drug release is approved in the United States for use with saline. Recently, the Propel mometasonefuroate-releasing stent designed by Intersect ENT received premarket approval from the FDA for use in the ethmoid sinus, making it the only drug-eluting nasal implant with FDA approval to date. ^[20] This device was evaluated for safety and efficacy by numerous studies prior to FDA approval. ^{[21, 22, 23, 24]}

Use of the Propel device in the frontal sinus as a stent is currently off-label.

Table 1. Drug-Eluting Stent Studies by Author and Year (Open Table in a new window)

Anesthesia

General anesthesia is used for the vast majority of sinus surgery. However, in-office frontal sinus stenting can be performed in select patients whose statuses are post ethmoidectomy and post frontal sinusotomy with an amenable frontal neo-ostium. In-office stenting requires frontal sinus equipment, as well as topical and infiltrative local anesthesia.

Perioperative management

In the perioperative period before and after placement of frontal sinus stents, patients should perform a regimen of frequent nasal saline irrigation and topical nasal steroids to minimize blockage from dried mucus and ameliorate scarring and adhesions. Many sinus surgeons also advocate for a course of postoperative oral antibiotics; however no consensus exists as to the optimal duration of therapy. Oral steroids ^[9] and topical budesonide irrigations (off-label use) are also recommended by some surgeons, especially in cases of marked polypoidal disease.

Patients should be followed with periodic office visits for intranasal examination, debridement, and stent cleaning, which helps maintain patency. Stents are removed in the office after a variable period of time. The goal is to keep them for the minimum duration that allows for remucosalization. Although stents are well tolerated by most patients, potential complications include stent displacement and the need for removal due to patient discomfort.

Duration of stenting

Frontal sinus stents are typically removed after the frontal sinus outflow tract has remucosalized and the healing process is complete (see the image below).

Frontal sinus stenting in a Draf III cavity. A Draf III (endoscopic modified Lothrop) procedure was performed in a patient with right frontal muco-pyocele and extensive osteitis in the frontal recess. (A) Frontal neo-ostium after modified Lothrop with extensive bone devoid of mucosal lining. (B) Soft silastic stent placed in the neo-ostium for 6 weeks. (C) Well-healed and remucosalized frontal neo-ostium at 6 months postoperatively.

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The optimal duration of frontal sinus stent maintenance has yet to be determined by empiric evidence, but stents should be removed as early as possible given clinical circumstances. Authors have recommended stenting periods ranging from 1 week to 6 months or longer. Primary frontal sinusotomies likely require a shorter duration of stenting. Metson used a 4-mm silastic stent in cases in which the frontal sinus ostium had been surgically enlarged. The stent was removed 1-8 weeks after surgery (average 3.2 weeks). The healed neo-ostium remained patent at follow-up 19-24 months postoperatively. ^[25]

In Rains’ series of 102 stents, average stent removal was performed at 35 days, with a range of 6-130 days. This was predicated upon re-epithelialization of the ethmoidectomy site, absence of significant purulence, and resolution of polypoid mucosa. ^[7] However, according to other literature, wound healing in the paranasal sinuses following major surgery may take up to 3 months. ^[16] When considering stent duration, thought should also be given to Perloff and Palmer’s finding of bacterial biofilms on frontal recess stents removed from patients 1-4 weeks after placement. ^[11]

Recent developments include a trend toward long-term maintenance of frontal sinus stents in patients deemed to be at high risk of restenosis. Long-term frontal sinus stents are defined as those in place for 3 months or longer. Numerous studies have shown long-term stenting to be well tolerated by patients. ^{[3, 9, 15, 26]} Weber et al showed that stents left in place for 6 months are more effective than those removed earlier based on outcomes measures. ^[15]

Lin and Witterick found that stents could be safely left in place for an average of 16.3 months but recommended long-term stenting only in patients with chronic frontal sinus disease resistant to standard endoscopic frontal sinusotomy. ^[26] In 2009, Orlandi and Knight published their data of frontal sinus stents placed over a 6-year period, revealing an average stenting duration of 32.6 months, with only 2 of 9 patients requiring removal of stents up to 6 years after placement. ^[3] Hunter’s series of 3 patients tolerating stents from 48 to over 60 months adds support for patient tolerance and functionality of long-term stenting. ^[9]