Unusual stylocarotid artery syndrome—a vascular variant of Eagle syndrome

Abstract

Clinical Presentation

Case 1: A 57-year-old female patient presented with a chief complaint of left-sided pain in her throat, especially upon yawning, bilateral deep pain at the left mandibular angle, odynophagia, and difficulty rotating head. There was no history of trauma. Panoramic radiograph demonstrated pronounced left stylohyoid ligament ossifications. Her symptoms did not resolve even after removal of the ossified left stylohyoid ligament. Multidetector computed tomography imaging revealed constriction of the left internal carotid artery (ICA) between the left styloid process and transverse process of C1.

Case 2: A 68-year old female patient presented with a chief complain of earaches, neck pain, and headaches on the left side. The patient also complained of pain in posterior and superior portion of the left side of her head with tenderness near the left occipital nerve. Cone beam computed tomography examination revealed extensive bilateral ossified stylohyoid ligament with narrow space between the styloid process and the transverse process of C-1 on the left side.

Differential Diagnosis

The clinical presentation and radiographic findings were consistent with stylocarotid artery syndrome as the radiographic diagnosis.

Diagnosis and Management

The treatment options include anticoagulation, thrombectomy, or surgical removal of the prominent styloid process. Bone reshaping of C1 is also advised treatment in some cases for preservation of the styloid muscles and ligaments.

Conclusion

The internal carotid artery compression by anomalous anatomical structures is rare. However, this can lead to the development of neurovascular complications related to mechanical impingement of the ICA. In both our cases the impingement of the ICA was related to decreased space between the styloid process and C1. These decreased distances between the stylohyoid-C1 complex may result in mechanical injury and predispose to carotid artery dissection, pseudoaneurysm and thromboembolism (carotid artery entrapment syndrome). Oral and maxillofacial radiologists should routinely evaluate styloid/C1 transverse process juxtaposition avoid these complications.