Carotid artery dissection associated with long styloid process

A 68-year-old male with a history of high blood pressure was admitted to the emergency department for sudden onset speech difficulty not associated with headache, neck pain or any head or neck manipulation or trauma. Pertinent clinical findings included normal vital signs, mild motor predominant aphasia, slight right inferior facial palsy and a National Institutes of Health Stroke Scale score of 3. A brain computed tomography (CT) revealed early ischemic changes in the left frontal and insular cortex. CT-angiography (Panel A-1) displayed a dissection of mid-cervical left internal carotid artery with mild narrowing of the arterial lumen (arrowhead), an eccentric mural hematoma (asterisk) and a distance of 4 mm between the styloid process (arrow) and the internal carotid artery. Further analysis of the CT-angiography confirmed bilateral elongated styloid processes (left=46 mm, right=38 mm) with medial angulation (Panels A-2 and A-3). The patient was started on antiplatelet therapy and further etiological investigation was negative (echocardiography, Holter monitoring and blood tests).

Panel A.

Eagle syndrome was described in the first half of the 20th century, and the first case in which a causal relationship was proposed to exist between an elongated styloid process and an internal carotid artery dissection was documented in 1999 by Zuber et al. ¹ Recently, two independent case–control studies found an association between carotid artery dissection and longer ipsilateral styloid processes ² and shorter styloid process – internal carotid artery distances, ³ even in the absence of Eagle syndrome. It is generally accepted that the styloid process is elongated if its length is greater than 30 mm. ⁴ Few studies have defined the normal styloid process – internal carotid artery interval. In one analysis of patients without cervical artery dissection, the mean distance was 7–8 mm. ⁵ Our patient did not manifest the clinical characteristics of Eagle syndrome; specifically, previous symptoms of cervical, facial or throat pain, otalgia, dysphagia or carotidynia. Therefore, only a careful analysis of the CT-angiography revealed the close and, in our opinion, causal relationship of the long styloid process and the internal carotid artery dissection.

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