Computed Tomography Analysis of the Anterosuperior Portion of the Bulla Lamella in Chinese Subjects and Its Surgical Significance in Endoscopic Frontal Sinusotomy

Introduction: The anterosuperior portion of the bulla lamella can extend into the frontal sinus and form the supra bulla frontal cell (SBFC) and supraorbital ethmoid cell (SOEC). This can affect the frontal drainage pathway and make surgery more challenging. Objectives: The aim of the study was to compare the anatomical characteristics of SBFC and SOEC in Chinese chronic rhinosinusitis (CRS) patients and explore the relationship between the cells and frontal sinusitis (FS). The surgical skills in dealing with these cells were also studied. Methods: We prospectively identified SBFC and SOEC in 114 patients with CRS by computed tomography (CT). The sides of the patients were divided into groups A (with FS) and B (without FS). CT scans were analyzed to distinguish the SBFC, SOEC, and the drainage pathway. Statistical analysis was conducted to determine whether the cells were associated with the occurrence of FS. Results: The prevalence of frontal cells was as follows: SBFC: 9.65%, SOEC: 21.93%. There was an association between the presence of SBFC and FS (p < 0.05). The anterior drainage pathway was present in patients with SBFC and SOEC, anterolateral pathway in those with SBFC/SOEC coexisting with the frontal septal cell, and anteromedial pathway in those with SBFC/SOEC coexisting with the supra agger frontal cell. Conclusions: There was an association between the presence of SBFC and the occurrence of FS. Extension of the anterosuperior portion of the bulla lamella into the frontal sinus obstructed the drainage pathway posteriorly. Understanding the anatomy may help surgeons thoroughly dissect the bulla lamella.