Rates of Middle Meatus (MM) Synechiae Formation Post Endoscopic Sinus Surgery (ESS): A Double-blind Randomized Controlled Study Comparing Silastic and Restora™ Steroid Eluting MM Spacer

Endoscopic sinus surgery (ESS) is the gold standard surgical intervention for chronic rhinosinusitis that is not adequately controlled with medical therapy. Synechiae formation in the middle meatus is the most common complication of endoscopic sinus surgery. Synechiae describes the adhesion of two opposing mucosal surfaces in the nasal cavity that can cause scarring and obstruction of the nasal passage. Incidence of synechiae formation varies in literature and ranges between 4-35 %. Presence of middle meatal synechiae can impair sinus drainage, promote sinusitis, and limit endoscopic visualization of the sinus cavities postoperatively. This may result in difficulty in performing postoperative routine endoscopic debridement and examination, which is paramount to a successful outcome from ESS.

To prevent synechiae formation, numerous studies have been published evaluating the effectiveness of absorbable and non-absorbable spacers placed in the middle meatus for 1-2 weeks postoperatively. The spacer is meant to prevent contact between the denuded surfaces of the middle turbinate and the lateral nasal wall during re-epithelialization. In general, non-resorbable spacers that have been used include sponges, cotton gauze and plastic sheets. Of these, Silastic Silicone sheets have been used in a number of hospitals across the US and Canada. Lee and Baguley have demonstrated the effectiveness of Silastic spacers in reducing the risk of synechiae formation to between 0-6 %. There are also a number of resorbable spacers that are in use, which are preferred by some physicians because there is minimal need to remove the packing materials as they naturally are removed or resorbed during the healing period.

In a recent meta-analysis, Lee et al has revealed that usage of middle meatal spacers (absorbable and non-absorbable) did not decrease the rate of synechiae formation to a statistically significant degree compared to not using any spacer. However, when subgroup analysis was performed, non-absorbable spacer usage demonstrated a statistically significant lower incidence of synechiae compared to no spacers. This can be explained in part by an inherent capability of the absorbable spacer material to degrade to smaller size particulates that, if caught in the healing tissue, could illicit local inflammatory response to slow down the healing and cause further synechiae formation. This mechanism was demonstrated by Maccabee et al in a rabbit model, where fibers of the absorbable spacer became incorporated into healing mucosa and increased the extent of the inflammatory response and formation of fibrosis.

To improve outcomes, physicians have attempted to load steroids such as Triamcinolone and antibiotics such as Neosporin into nasal packing and/or stents. However, residence of the drug in the intended treatment space is minimized as the drug, which is not bound to the spacer, quickly releases and may not remain long enough to impact inflammatory response. A Mometasone Furoate coated stent (Propel™), manufactured by Intersect ENT, is currently the only drug coated nasal stent that has a claim of longer sustained release. In a randomized, controlled, double-blind trial, Marple et al found that this Mometasone Furoate steroid-eluting bio-absorbable stent could significantly improve postoperative outcomes compared to a non-steroid eluting placebo arm with the same stent. Zhao et al conducted a systematic review of the efficacy of this steroid-eluting stent (Propel) vs inert (both resorbable and non-resorbable) spacers and again confirmed that there are lower rates of synechiae formation in the steroid-eluting treatment groups. However, anecdotal evidence, based on discussion with a number of surgeons in the field, suggests that a drug-loaded resorbable spacer may be subject to the same issues as non-drug-loaded resorbable spacers, namely late stage degradation of the material that can cause a secondary spike of the inflammatory cascade, requiring additional surgical intervention to remove the remaining debris.

Therefore, it has been hypothesized that a steroid eluting non-absorbable spacer may provide optimal benefit for the patient's outcome. The Restora™ spacer is made of a biocompatible non-resorbable material that is expected to deliver up to 370 µg of Mometasone Furoate. The steroid elutes out of the spacer and onto the surrounding mucosal tissue during the 6-8 day period during which it is retained.