Morphometric analysis of the stylohyoid complex

Stylohyoid complex is anatomical structure predisposed to numerous individual variations. These may result in its extreme elongation, medial deviation and finally Eagle's syndrome occurrence. The aim of this study was to measure the length, angulation, evaluate morphological variations of stylohyoid complex by computed tomography and, subsequently, relate obtained data to the gender and the age of the evaluated cases.

The material included CT scans of stylohyoid complexes of 282 individuals. The entire length, maximal thickness, and angulation of the stylohyoid complexes in the coronal, transverse, and sagittal planes were measured.

According to their morphology, orientation and length, stylohyoid complexes were classified into six morphological types. Elongated, bent, segmented, and segmented with attached stylohyoid ligament for the lesser horns of the hyoid bone stylohyoid complex types were characterized by significantly greater length, while pseudoarticulated type was characterized by significantly lower length in relation to normal stylohyoid complex type. The elongated type was additionally significantly thicker and with significantly lower value of medial angle in transverse plain than the normal stylohyoid complex type. Elongated, bent, and segmented types were significantly more frequent in males than in females. Furthermore, the frequency of the elongated stylohyoid complex type increased, whereas normal and pseudoarticulated types decreased with age.

In conclusion, elongated and more medially deviated stylohyoid complexes are more frequent in males than in females. Their more frequent presence in the older age groups indirectly connects this phenomenon with the aging process.