Internal carotid artery dissection as a possible complication of Eagle syndrome

A 38-year-old female patient presented to the Emergency Department complaining of an intense headache upon waking up, accompanied by left hemiplegia, and dysarthria.

A CT was performed, showing a hyperdense Sylvian fissure “dot” sign (Figure 1). No signs of acute ischemic injury were observed. ASPECTS: 10 (Figures 2a and 2b).

A CT perfusion showed an increase in mean transit time and venous drainage time, with decreased blood flow, and conservation of cerebral volume in the territory of the right middle cerebral artery (Figures 3a, 3b, 3c, and 3d).

A CT angiography and an angiogram demonstrated right internal carotid dissection caused by an elongated styloid process. Stenting of the internal carotid artery was performed (Figures 4a, 4b, 4c and 4d). Also observed was an occlusion of the superior division M2 of the middle cerebral artery. Therefore, a mechanical thrombectomy was performed (Figures 5a, 5b, and 5c).

Eagle syndrome is a symptomatic elongation of the styloid processor or calcification of the stylohyoid ligament [1,2]. It is a rare, unknown entity. The styloid process is an extension of bone that normally varies in length from 2 to 3 cm, becoming the cause of Eagle syndrome when it exceeds 4 cm [2].

Clinical presentation is varied and originates from the compression of adjacent anatomical structures by the styloid processor or calcification of the stylohyoid ligament. It can be divided into two main variants: classical and vascular [3].

In the classical variant, the patients can have symptoms caused by compression and irritation of cranial nerves in the region, especially the glossopharyngeal nerve, inducing dysphagia and neck pain [3].

In the vascular variant, the patients can have symptoms due to compression of the carotid artery [1,3]. It can cause neurological symptoms because of the mechanical compression of the vessel or sympathetic plexus irritation. In rare cases, it can cause carotid dissection and ischemic stroke [3].

The diagnosis is based on clinical suspicion and imaging tests [1,4].

Head and neck X-rays may be helpful. However, computed tomography is the test of choice, as it provides data on the elongation of the processes and their relationship with adjacent structures [4,5]. Additionally, CT angiography can provide information on carotid flow, compression, and vascular damage [4].

The definitive treatment for Eagle syndrome is surgery to remove the styloid process/calcification stylohyoid ligament [6].

In cases of carotid artery dissection due to Eagle syndrome, endovascular management is necessary for carotid artery reconstruction (stenting and balloon angioplasty). If there is intracranial involvement as ischemic stroke, it may be necessary a thrombectomy [7].

Written informed patient consent for publication has been obtained.