Anatomical Measurement as a Reference for Functional Endoscopic Sinus Surgery Based on CT Scans and Dissections.

Introduction Diseases of the paranasal sinuses, nasal cavities, and those related to the skull base can be treated with nasal endoscopic surgery. Anatomical references are essential to safely perform these surgeries. Objective To measure and compare the distance from the posterior wall of the maxillary sinus to the anterior skull base in cadavers and on computed tomography (CT) scans to determine a measurement as an anatomical reference in imaging exams for sinus and anterior skull base surgery. Methods In dissections and CT scans, we took measurements from the most upper and medial point of the posterior wall of the maxillary sinus (point A) to the point where the skull base deflects and the anterior sphenoid wall is formed (Δ 90°; point B), in the right and left nasal cavities. We used 51 cadavers aged ≥ 18 years in the present research. Results The measurements obtained from CT scans and dissections were greater than 1.5 cm in all cadavers, and they were positively correlated. The 1-cm increase in the AB-tomography measurement corresponded to the 1.08-cm increase to the right and 1.07-cm to the left in the AB-dissection measurement. Conclusion The CT measurements may be considered a reliable tool to promote safe and effective access to the paranasal sinuses, matching the distance that should be dissected until the anterior base of the skull.

Setting of an endoscopic nasal reference point for surgical access to the anterior base through an anatomical study on cadavers / Definição do ponto de referência endoscópica nasal ao acesso cirúrgico à base anterior por estudo anatômico em cadáveres

Abstract Introduction: Diseases of paranasal sinuses, nasal cavity, and skull base can be treated by endonasal operations using a nasal rigid endoscope. When conducting this kind of surgery, anatomical references are critical for safety. Objective: To measure the distance from the posterior wall of the maxillary sinus to the skull base, according to socio-demographic characteristics, and to detail an anatomical reference point for paranasal sinus operations and for an access to the anterior skull base, comparing anatomical variations between right and left sides, gender, height, weight, age, and ethnicity in cadavers. Methods: Measures were taken from the 90° angle (the starting point where deflection of the skull base begins to form the anterior wall of the sphenoid, also known as Δ90°) to the upper, middle, and lower points of the posterior wall of the maxillary sinus. This study used 60 cadavers aged over 17 years, and evaluated these bodies with respect to age, height, BMI, weight, gender, and ethnicity, comparing measurements of right and left sides. Results: The measurements were >1.5 cm in all cadavers and did not vary with age, height, weight, gender, and ethnicity on their right and left sides. The lack of association between the measurement from Δ90° to the upper, middle, and lower posterior walls of the maxillary sinus (categorical or quantitative) is noteworthy, considering the characteristics studied. Conclusion: The methodology defined the nasal point of reference, considering an absence of variation in the cadavers’ characteristics.

Resumo Introdução: Doenças dos seios paranasais, cavidades nasais e doenças da base do crânio podem ser tratadas com operação endonasal utilizando-se endoscópio rígido nasal. Referências anatômicas são importantes para a segurança durante a realização dessas operações. Objetivo: Medir a distância da parede posterior do seio maxilar à base anterior do crânio de acordo com características sócio-demográficas. Detalhar um ponto de referência anatômico para operações dos seios paranasais e acesso à base anterior do crânio comparando variações anatômicas entre os lados direito e esquerdo, gênero, altura, peso, idade e etnia em cadáveres. Método: Medidas do ângulo de 90º (ponto onde inicia a deflexão da base do crânio para formar a parede anterior do esfenoide, chamado de ângulo de 90º – Δ_90º) aos pontos superior, médio e inferior da parede posterior do seio maxilar. Foram utilizados 60 cadáveres com idade acima de 17 anos, e avaliados com idade, altura, peso IMC, gênero e etnia, comparando-se as medidas dos lados direito e esquerdo. Resultados: As medidas foram maiores que 1,5 cm em todos os cadáveres e não variaram com a idade, altura, peso, gênero e etnia nos lados direito e esquerdo dos cadáveres. Destaca-se falta de associação entre a medida do Δ90º à parede posterior superior; média e inferior do maxilar (categórico ou quantitativo) com as características estudadas. Conclusão: A metodologia empregada definiu o ponto de referência nasal por não variar com as características dos cadáveres.

Setting of an endoscopic nasal reference point for surgical access to the anterior base through an anatomical study on cadavers.

INTRODUCTION: Diseases of paranasal sinuses, nasal cavity, and skull base can be treated by endonasal operations using a nasal rigid endoscope. When conducting this kind of surgery, anatomical references are critical for safety. OBJECTIVE: To measure the distance from the posterior wall of the maxillary sinus to the skull base, according to socio-demographic characteristics, and to detail an anatomical reference point for paranasal sinus operations and for an access to the anterior skull base, comparing anatomical variations between right and left sides, gender, height, weight, age, and ethnicity in cadavers. METHODS: Measures were taken from the 90° angle (the starting point where deflection of the skull base begins to form the anterior wall of the sphenoid, also known as Δ90°) to the upper, middle, and lower points of the posterior wall of the maxillary sinus. This study used 60 cadavers aged over 17 years, and evaluated these bodies with respect to age, height, BMI, weight, gender, and ethnicity, comparing measurements of right and left sides. RESULTS: The measurements were >1.5cm in all cadavers and did not vary with age, height, weight, gender, and ethnicity on their right and left sides. The lack of association between the measurement from Δ90° to the upper, middle, and lower posterior walls of the maxillary sinus (categorical or quantitative) is noteworthy, considering the characteristics studied. CONCLUSION: The methodology defined the nasal point of reference, considering an absence of variation in the cadavers' characteristics.