Dynamic assessment of internal carotid artery and elongated styloid process in a case of bilateral carotid artery dissection

Background Vascular Eagle syndrome is that an elongated styloid process causes ischemic stroke due to internal carotid artery (ICA) dissection. Dynamic assessment using radiological imaging has not been well investigated. We assessed the change in the relative positional relationship between the elongated styloid process and the ICA using a cone-beam computed tomography (CBCT). Case Description A 46-year-old female presenting with disturbance of consciousness, right hemiparesis, and aphasia was admitted to our hospital. Initial CT analysis showed a bilateral elongated styloid process. Magnetic resonance angiography (MRA) showed occlusion of the left ICA and a near occlusion of the right ICA. MRA also revealed the intimal flap and intramural hematoma in the bilateral ICA. Digital subtraction angiography showed bilateral ICA occlusion and carotid artery stenting was performed subsequently. After that, we visualized the movement of carotid stent with CBCT fusion methods. The stent moved forward and backward at the attachment point of the styloid process during head rotation, and there was a possibility that mechanical stress was emphasized at this point. Styloidectomy was performed after her rehabilitation. The patient did not experience a recurrence of stroke. Conclusion We showed that repeated attachment of the styloid process and ICA may trigger an ICA dissection during head rotation. This finding would be helpful for understanding the causes of vascular Eagle syndrome.