The distribution of stylohyoid chain anatomic variations by age groups and gender: an analysis using MDCT

The aim of this study is to investigate the frequency of the SHC variations, and the distribution of the SP lengths in different age and sex groups using MDCT. MDCT scans were performed in 805 patients (401 males, 404 females). The patients were divided into six groups according to their ages. The length of the styloid process (SP) and its angulation on the transverse (TA) and sagittal (SA) planes were measured. Structural variations of the SHC were observed by means of three-dimensional (3D) and multiplanar reconstruction (MPR) images. Absence of the styloid process (n = 10), double proximal origin (n = 13), segmentation (n = 223), complete ossification (n = 24), and an SP with three proximal parts in one patient were among the anomalies detected. The mean length of the SP was greater in males than in females (33.2 ± 13.2 vs. 29.6 ± 10.5 mm, P < 0.001). Elongated SP (ESP) was observed in 56 % of the patients in the study group, and this ratio was the highest in Group 3 with 65.4 % (P < 0.05). TA and SA were 70.2° ± 4.1°, 69.9° ± 4.2° and 86.6° ± 6.5°, 88.3° ± 6.6° for the right and left sides, respectively. Besides, 3D and MPR images also present detailed and reliable data to radiologists and surgeons for the evaluation of the SHC. ESP has been detected in more than half of the patients, being more frequent in males and in individuals in the fifth decade of life. For an accurate diagnosis, clinicians should consider the ESP while evaluating the patients in this age group.