The gender and side asymmetry of length of the styloid process

Abstract

The styloid process is a sharp bony projection, at the base of the skull, and part of the temporal bone. Muscles and ligaments are attached to this process, but they are rarely of any clinical significance unless the styloid process is fractured or severely elongated. Pathology of the styloid process is referred to as Eagle’s syndrome. This was after a publication by Eagle (1937) in which he reported a 4% prevalence of elongated styloid processes. Later studies reported much higher percentages of elongated processes. The aims of this study was to investigate the mean length of the styloid process and compare this with what is accepted as the “normal” length after the Eagle publication. The study also looked at evidence of asymmetry between the two sides within the same specimen. Comparison in the lengths between the two sexes were also made. Forty-five styloid processes from 28 different individuals were measured for comparison. The sample group consisted out of 18 males- and 10 female subjects. The lengths of the styloid processes varied from 7.17 – 50.54mm, with a mean of 27.48mm. Styloid processes were on average 0.87mm longer on the right side and 3.12mm longer in the male specimens. This mean length of 27mm supports the claim by Eagle that the “normal” length is around 25mm. Ten out of 25 individuals (40%) exhibited “elongated” styloid processes measuring over 25mm. These findings were higher than those reported by Eagle. Elongated styloid processes are clinically important in order to make the correct diagnosis.

Keywords: Styloid process; Eagel’s Syndrome; Elongated (abnormal length) styloid process.