Assessment of Normal Intracranial Parameters of the Sellar Region in Healthy Subjects of South Indian Population: A Retrospective Study

Abstract

Introduction: There is a significant degree of anatomical variation at the level of the sphenoid sinus and sella turcica and a wide range of these values have been reported in literature and ethnic variation has also been found to contribute to this. Thus preoperative imaging of the central skull base with a knowledge of the normal anatomy and measurements in a specific population is imperative to identify these variations and prevent avoidable intraoperative complications. Aim: To assess the normal intracranial measurements of the intercarotid distance, pituitary fossa width, optic chiasm height, optic chiasm width and the pituitary to optic chiasm distance in healthy subjects of the South Indian population aged between 10 to 80 years and establish normal reference ranges across the various age groups. Materials and Methods: This retrospective study was conducted in the Radiology Department at SRM Medical College Hospital and Research Centre, Chennai, Tamil Nadu, India, from July 2021 to December 2021. The study included normal Magnetic Resonance Imaging (MRI) brains of 700 healthy subjects (378 males and 322 females) in the age range of 10 to 80 years. Subjects were divided into seven groups of 100 subjects for each decade. The variables that were measured included the intercarotid distance, pituitary fossa width, optic chiasm height, optic chiasm width and the pituitary to optic chiasm distance. RStudio version 1.2.1093 was used for statistical analysis and p-value <0.05 was considered statistically significant. Association between age and outcome variables was assessed by Pearson’s correlation coefficient and its 95% confidence interval. Results: The overall mean age was 45.4 years. The overall mean intercarotid distance was 16.2±3.7 mm, optic chiasm width was 13.1±1.6 mm, optic chiasm height was 2.18±2.7 mm, pituitary width was 12.1±2.3 mm, pituitary to optic chiasm distance was 5.7±1.84 mm. The overall pituitary fossa width and pituitary to optic chiasm distance was found to be higher in males (p-value <0.001; p-value=0.03 respectively) than females while there was no significant difference between genders in the rest of the parameters. A low and positive correlation was found between age and the pituitary width, age (r-value=0.175, p-value <0.001) and the pituitary to optic chiasm distance (r-value=0.342, p-value <0.001) and pituitary width and optic chiasm width (r-value=0.236, p-value <0.001). A strong and positive correlation was found between the pituitary width and the intercarotid distance (r-value=0.736, p-value <0.001). Conclusion: Establishment of normal reference values across various age groups of the South Indian population may prove useful for future reference and improving diagnostic accuracy.