Angulation, Length, and Morphology of the Styloid Process of the Temporal Bone Analyzed by Multidetector Computed Tomography

Purpose: To investigate the angulation, length, and structural variations of the styloid process (SP) by multidetector computed tomography (MDCT).

Material And Methods: MDCT scans were performed in 283 cases (127 M and 156 F, age range 18-77 years). The length of the SP and its angulation on the transverse and sagittal planes were measured. Structural variations of the SP were observed by means of three-dimensional (3D) and multiplanar reconstruction (MPR) images.

Results: The length of the bony SP on both sides varied from 0 to 62 mm (mean 26.8 +/- 10.0 mm). Angulation ranged between 55 degrees and 90.5 degrees (7 2.7 +/- 6.6) in the transversal plane and between 76 degrees and 110 degrees (93.5 +/- 6.9) in the sagittal plane. Morphologically, the SP showed a considerable amount of variation. A solitary SP was present in 168 individuals (59.4%). In 9 individuals (3.1%), the SP was duplicated (4 unilateral and 5 bilateral). Sixty-one persons (21.6%) showed an incomplete ossified SP (42 unilateral and 19 bilateral), whereas in 7 individuals (2.5%) a bony SP was absent entirely (7 unilateral). In 38 individuals (13.4%), the stylohyoid ligament was ossified (16 entirely, 22 partial). In all individuals, 3D and MPR images showed the SP in its entire length.

Conclusion: MDCT with 3D CT and MPR of SP may show further detailed information related to SP. Not only the length of the SP, but also its 3D orientation, should be in focus in anatomical and clinical studies.