The Anatomy of the Stylohyoid Chain: A Systematic Review with Meta-Analysis

Area of Science:

• Anatomy
• Radiology
• Otolaryngology

Background:

• The temporal bone's styloid process (SP) and stylohyoid ligament (SHL) form the stylohyoid chain (SHC).
• Variations in the SHC, particularly SP elongation, have clinical significance due to proximity to vital head and neck structures.
• Understanding SHC anatomy and variants is crucial for clinical practice.

Purpose of the Study:

• To systematically review and meta-analyze the prevalence of typical stylohyoid chain (SHC) anatomy and morphological variants.
• To determine the pooled mean length of the styloid process (SP).
• To identify optimal imaging modalities for SHC variants.

Main Methods:

• Systematic literature review of four databases (PubMed, Google Scholar, Scopus, Web of Science).
• Inclusion of studies on typical SP anatomy and SHC morphological variants.
• Meta-analysis using R software to calculate pooled prevalence and mean SP length.

Main Results:

• A total of 104 studies with 136,010 heminecks were analyzed.
• Typical SP ( < 30 mm) prevalence was 74.97%; elongated SP (> 30 mm) prevalence was 25.03%.
• Pooled mean SP length was 28.91 mm. Pseudo-articulated SHC ossification: 4.39%; segmented: 3.89%. Computed tomography (CT) showed higher prevalence.

Conclusions:

• The elongated styloid process (SP) is a common variant (25.03%), not a rare finding.
• Computed tomography (CT) is the optimal imaging modality for detecting SP variants.
• This meta-analysis provides essential data on SHC anatomy and variants for clinicians.