Evaluation of Styloid Process Length using Multidetector Computed Tomography Scan in Indian Population: A Cross-sectional Study

Introduction: The length of the Styloid Process (SP) has been a subject of research since Eagle's case report on a syndrome characterised by symptoms related to a painful elongated SP. Various modalities including orthopantomogram, digital radiography, cadaveric measurements, and Multidetector Computerised Tomography (MDCT) scanning have been used to study SP length. The present study aims to determine the normal SP length in the Indian population, specifically among armed forces personnel, using MDCT scans. Aim: To measure the SP length in the Indian population using MDCT scans and establish a cut-off length to define elongation. Materials and Methods: A single centre cross-sectional study was conducted at the Department of Radiology, Command Hospital Pune, Maharashtra, India from January 2023 to March 2023. The SP length was measured in 402 patients referred for CT scans of the head and Paranasal Sinus (PNS), utilising 3D Multiplanar Reformation (MPR), curved reformat, and volume rendering techniques. The patients were divided into six age groups: Group I (<20 years), Group II (21 to 30 years), Group III (31 to 40 years), Group IV (41 to 50 years), Group V (51-60 years), and Group VI (>60 years). Statistical analysis was performed using the Statistical Package for Social Sciences (SPSS) Version 28.0, and significance was set at p-value <0.05. Results: Among the 402 patients, 210 were males, and 192 were females, with a mean age of 43.8±16.7 years. The mean SP length across all patients was 23.24±3.92 mm. The mean length was 23.74±4.50 mm on the right side and 22.74±3.72 mm on the left side, with no statistically significant difference between them (p-value=0.058). There was a significant gender difference, with males having a mean length of 23.67±4.12 mm and females 22.77±3.64 mm (p-value=0.011). The SP length increased significantly with age, demonstrating a notable difference between age groups. The upper limit of normal (90th percentile) ranged from 25.74 mm for patients <20 years to 28.91 mm for patients >60 years. Conclusion: A statistically significant difference in SP length was observed between genders, with a significant increase in length with age. In the Indian population, an SP length greater than 28 mm should be considered elongated.