An evaluation of the prevalence of elongated styloid process in Taiwanese population using digital panoramic radiographs.

Background/purpose: Styloid process (SP) was an anatomical structure located in front of the stylomastoid foramen and the occurrence of styloid process elongation was uncertainly reported. The purpose of this study was to survey, using digital panoramic radiography, the lengths of styloid process (SP) and the prevalence of elongated SP in the Taiwanese population. Their relationships with age, gender and laterality were also determined. Materials and methods: A total of 539 patients (including 53 that were referred from the Department of Otorhinolarygngology with clinical symptoms) were studies retrospectively. Panoramic radiographic examinations were performed on all these patients at the Outpatient clinics of the Department of Stomatology, Taichung Veterans General Hospital between January 2019 and December 2019. Patients were divided into groups according to their age and gender. The length of SP from the base of temporal bone junction to the tip of the process was measured using the Sirona software. Data were analyzed using SPSS version 22.0 based on tests of Chi-square, Mann-Whitney U and Kruskal Wallis tests. Statistical significance was set at p < 0.05. Results: A total of 539 (240 males and 299 females) digital panoramic radiographs were measured and evaluated in this study. The mean length of SP was 30 ± 0.7 mm on the right side and 29 ± 0.7 mm on the left side. The average length of SP on both sides was 29.5 ± 0.7 mm. In those cases with symptomatic Eagle syndrome, the mean length of SP was 32 ± 0.8 mm on the right side and 33 ± 0.8 mm on the left side (average 32.5 ± 0.8 mm). These lengths were statistically different between the general population and the symptomatic patients. Furthermore, the mean length of SP was 29 ± 0.7 mm in females and 30 ± 0.7 mm in males. The length of the SP grew progressively with age, and was more clearly seen within subjects from 41 to >60 years of age (p < 0.005). Meanwhile, the prevalence of elongated SP in our study was 41.5% on the right side and 36.2% on the left side, with female predominance. Conclusion: The mean length of SP was 30 ± 0.7 mm (right side) and 29 ± 0.7 mm (left side). The prevalence of elongated SP was 41.5% on the right side, and 36.2% on the left side. Our findings were consistent with some previous studies that were differences related with age, and were more prominent in those patients with symptoms.