The Unzip Technique for Removal of Large Supra Agger Frontal Cells (SAFC or Formerly Kuhn Type 3) during Endoscopic Frontal Sinusotomy

Abstract


Objectives: To evaluate performing endoscopic frontal sinusotomies in the setting of large supra agger frontal cells (SAFC or formerly known as Kuhn type 3 frontal cells) using the unzip technique during endoscopic sinus surgery. Methods: A review of prospectively collected data was performed of 32 consecutive patients (37 sides) who underwent endoscopic frontal sinusotomies for SAFCs between January 2012 and October 2016 to identify and evaluate subjects the unzip technique for removal of SAFCs was performed. Data collected and analyzed included demographics, CT imaging characteristics, findings at surgery, use of frontal sinus stents, preoperative and postoperative SNOT-22 quality of life scores, primary versus revision surgery, and size of intraoperative and postoperative frontal sinusotomy, and complications. The operative technique was described. Results: Eighteen (18) subjects (23 sides) underwent successful frontal sinusotomies and removal of SAFCs using the unzip technique. All sides had endoscopically confirmed persistent postoperative patency with a mean follow-up of __._ months. None of the patients required revision surgery. No cases of CSF leak, epistaxis requiring packing or cauterization, or orbital injury occurred. Conclusion: The unzip frontal sinusotomy technique for removal of Kuhn type 3 frontal cells provides safe and effective access to the native frontal sinus when the natural outflow tract can be identified. Key Words: Anatomy, frontal sinusitis, sinus surgery, endoscopic, frontal cell.

Introduction


Surgery of the frontal sinuses remains one of the most difficult aspects of endoscopic sinus surgery (ESS).DeConde 2016 The complex anatomy and high variability of the frontal outflow tract result in higher rates of stenosis in frontal sinus surgery than surgery in the other paranasal sinuses. The Bent and Kuhn classification of frontoethmoidal cells is one of the most widely cited.Bent 1994 One particularly large frontal cell in the classication, the type 3 frontal cell, is described as a large cell above the agger nasi cell that invaginates into the frontal sinus cavity. A recent consensus review introduced "The International Frontal Sinus Anatomy Classification" in which the Kuhn-type type 3 frontal cells were renamed large supra agger frontal cells (SAFC) to provide more descriptive terminology.Wormald 2016 These classification systems are summarized in Table 1. Large SAFCs are particularly difficult to manage endoscopically because the frontal outflow tract narrows significantly at the level of the frontal cell and tends to be located posteromedially adjacent to the lateral lamella of the cribriform plate.Wormald 2016,Patel 2017 Surgery in this area thus may have higher risk of skull base injury and cerebrospinal fluid leak. Draf described extents of endoscopic frontal sinus surgery techniques.

Draf I is the most conservative procedure of the frontal sinus and includes removal of the posterior wall of the agger nasi cell. Draf IIa frontal sinusotomy is the opening of the frontal sinus outflow tract from the medial orbital wall to the middle turbinate, including removal of frontal cells or supraorbital ethmoid cells. Draf IIb frontal sinusotomy is an extended procedure with the removal of the frontal sinus floor and excision of part of the middle turbinate. Draf III frontal sinusotomy (also called modified Lothrop procedure) includes connecting the frontal sinuses with anterosuperior septectomy and removal of the intersinus septum.Weber 2001 Despite this classification, few surgical techniques have been published that specifically address approaches to large SAFCs during endoscopic frontal sinusotomy. Wormald described an axillary flap approach to the frontal recess that also mentions addressing SAFCs from an anterior approach and fracturing the cell with a curved curette; however, the author does not provide a detailed description of the technique in this article.Wormald 2002 A centrifugal frontal sinus technique has been described in which a curved image-guidance probe was used to puncture through the roof of the frontal sinus cell before further performing the sinusotomy from this initial site. This technique avoids the natural outflow tract and relies on image guidance accuracy.Yao 2015  

This study assesses a technique to safely and effectively performing endoscopic frontal sinusotomy through the natural outflow tract in the setting of obstructive SAFCs.