3D‐CT Comparison of the Stylohyoid Chain in Eagle's Syndromes, Glossopharyngeal Neuralgia, and Asymptomatic Controls

Abstract

Objectives: (1) Describe 3-dimensional (3D) computed tomography (CT) anatomic features of the stylohyoid chain in Eagle’s syndrome patients (ES), glossopharyngeal neuralgia patients (GPN), and normal asymptomatic controls (NC). (2) Understand 3D-CT features findings associated with Eagle’s syndrome. Methods: Retrospective chart review from November 2000 to November 2013. 3D shaded surface display CT reconstructions of the stylohyoid chain were generated for 10 ES patients, 16 GPN, and 15 NC patients. Demographic and clinical symptom data were recorded. Anatomic data collected from CT scans included: length of ossified styloid process, anterior-posterior (APA) and medial-lateral (MLA) styloid process angulation, ossification pattern of the stylohyoid chain, and minimum distances between the styloid process and the internal carotid artery, C1 transverse process, and tonsillar fossa. Results: The average distance from the styloid process tip to the tonsillar fossa was found to be significantly shorter in ES patients (12.7 mm) compared with GPN (21.4 mm; P < .05) or NC (24.8 mm; P < .001) patients. No other measured variables were found to be significantly different between groups, including average styloid process length (ES: 48.0 vs GPN: 40.3 vs NC: 40 mm; P > .05). Conclusions: The styloid process was found to be significantly closer to the tonsillar fossa in ES patients as compared to GPN and NC patients by 3D-CT reconstructions. No significant differences were found in other measures, including styloid process length. Distance to the tonsillar fossa may be a more appropriate diagnostic criterion for ES than styloid process length, and may contribute to the pathophysiology of ES.