Gender and Side Asymmetry in the Length of the Styloid Process

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 or structures attached to it becomes
ossified. Pathology of the styloid process is referred to as Eagle’s syndrome. This was after the first
publication by Eagle [1] in which he reported a 4% prevalence of elongated styloid processes in the
cohort that he investigated. Later studies reported a much higher percentage of elongated styloid
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 publication by Eagle. The study also looked at
evidence of asymmetry between the two sides within the same specimen. Comparing the lengths
between different sexual groups, were also investigated.
Forty five styloid processes from 28 different individuals were measured for comparison. The sample
group consisted out of 18 male- and 10 female subjects. The lengths of the styloid processes varied
from 7.17 – 50.54 mm, with a mean of 27.48 mm. This mean length of 27 mm supports the claim by
Eagle that the “normal” length of the styloid process is around 25 mm.
Ten out of 25 individuals (40%) exhibited “elongated” styloid processes measuring over 25 mm.
These findings were higher than those reported by Eagle. Elongated styloid processes are clinically
important in order to make the correct diagnosis if there is problems in the neck.
In our investigation the styloid processes were on average 0.87mm longer on the right side and 3.12
mm longer in male specimens.