Measurement of Normal Size of Styloid Process with 3D Reconstruction CT

Abstract

Purpose: To measure the normal size of the styloid process using 3D (three-dimensional) reconstruction CT. Materials and Methods: We retrospectively analyzed 3D reconstruction images obtained after coronal and axial CT scanning of the temporal bone or neck of 115 patients. The length and shape of both sides of the styloid process, the location of its tip, and calcification of the stylohyoid ligament were retrospectively analysed. Results: The mean length of the styloid process was 26.6 (7.9)mm on the right side, and 26.4(8.3)mm on the left, a statistically insignificant difference (p=0.694). Its mean length was 26.2 (8.5)mm in men and 26.7 (7.2)mm in women, a statically in significant difference (p=0.733). As for variation with age, mean length tended to increase until the third decade, but not beyond. Segmental type (104/230, 45.2%) and fragmental type (73/230, 31.7%) were more commonly seen in shape of styloid process, and tapering tip of styloid process (156/230, 67.9%) is more commonly seen than clubbing tip of it (74/230, 32.1%). The process was angulated in six cases (2.6%); its tip was more frequently located between the internal and external carotid artery (211 cases, 91.7%) than more medially (19 cases, 8.3%). In the former location, the length of the process was 26.2( 7.2)mm, and in the latter, 37.0(6.0)mm. The difference was statistically significant (p=0.000). Calcification had occurred in 33 cases (14.3%). Conclusion: The length of a normal styloid process was 18-32 mm. There were no statistically significant differences between its two sides, or between the sexes. Length tended to increase until the third decade, but not beyond. Predominantly the tip was located between the internal and external carotid artery, though the process was longer when its tip was located medially.