Carotid Artery Dissection Caused by an Elongated Styloid Process: Three Case Reports and Review of the Literature

Abstract

Eagle syndrome is a set of symptoms associated with an elongated styloid process. Although it is an important cause of cerebrovascular complications such as carotid artery dissection (CAD) or thromboembolism, the condition may be underdiagnosed. We treated three patients with CAD caused by an elongated styloid process within a year. The first patient was a 55-year-old man who developed recurrent thromboembolism despite anticoagulation therapy. Computed tomography (CT) angiography showed bilateral CAD with tips of styloid processes attached to the dissected lesions. He underwent surgical resection of the styloid process followed by carotid artery stenting. The second patient was also a 55-year-old man who developed acute stroke due to carotid artery occlusion, and underwent thrombectomy and carotid artery stenting. Both these patients experienced resolution of their neurological symptoms and had no recurrence of stroke. The third patient was an 80-year-old man with an asymptomatic dissecting aneurysm of the cervical internal carotid artery. He had a history of odynophagia and underwent surgical resection of the styloid process, with resolution of his symptoms. These cases, taken together with recent evidences showing that CAD was associated with the styloid process length, suggest that Eagle syndrome may not be an uncommon cause of CAD. Examination by CT angiography is important to avoid misdiagnosis. A literature review indicates that some cases were refractory to anticoagulation and surgical resection of the elongated styloid process or carotid artery stenting could be a treatment option to prevent further stroke.

Keywords: Eagle syndrome; carotid artery dissection; elongated styloid process; ischemic stroke; stylo-carotid syndrome.

Fig. 1

Preoperative diagnostic images in Case 1. A, B: T₁-weighted magnetic resonance imaging (MRI) images, showing a double lumen in both ICAs (A, circles) suggesting dissection, and thrombus in the pseudo-lumen on the left side (B, circle). C–E: Computed tomography (CT) angiograms of the elongated styloid processes in a 3-dimensional image (C) and maximum intensity projection (MIP) images on the right side (D) and on the left side (E). The styloid processes (arrows) were quite close to the ICAs.

Fig. 2

Postoperative images of Case 1 after surgical resection of the styloid process and carotid artery stenting. A, B: Computed tomography (CT) angiogram images after the resection of the styloid process. Detachment of the styloid process from internal carotid artery (ICA) was confirmed. Intimal flap in the right ICA was observed (B, arrow). C, D: Right common carotid artery angiogram before (C) and after (D) stent placement. After stent placement, the stenosis in the true lumen has been improved.

Fig. 3

A: Right internal carotid artery angiogram in Case 2 just after recanalization, showing irregular stenosis in the internal carotid artery (ICA). The position of the styloid process is shown with dotted lines. B: The stent was deployed to cover the dissection. C: Right common carotid artery angiogram after stent placement, showing complete restoration of the true-lumen. D: Computed tomography (CT) angiogram after stenting. The styloid process (arrow) was adjacent to the stented ICA.

Fig. 4

A: Preoperative computed tomography (CT) angiogram in Case 3, showing elongation of the left styloid process. B: The left styloid process (arrow) was adjacent to the internal carotid artery (ICA), causing dissection and aneurysmal change.