Dynamic imaging evaluation of the positional relationship between the elongated styloid process and the carotid artery stent using cone-beam CT: illustrative case.

Eagle syndrome is a condition in which mechanical stimulation of an elongated styloid process causes internal carotid artery (ICA) dissection. The patient presented with partial right hemiparesis and dysarthria and was diagnosed with left ICA occlusion due to dissection with horizontal segmental patency of the middle cerebral artery, for which carotid artery stenting was performed. The tip of the styloid process was at the same level as the entry of the dissected segment, suggesting mechanical stimulation of the styloid process as the cause of dissection. Dynamic evaluation of the positional relationship between the tip of the styloid process and the carotid artery stent during head rotation was performed with cone-beam CT. The distance between the tip of the styloid process and the carotid artery stent was shortest in the neutral position and increased with head rotation. Repeated head rotation while swinging a golf club was thought to be the cause of the ICA dissection in this patient. The greater the range of motion of the styloid process during head rotation, the greater the likelihood of mechanical stimulation of an elongated styloid process to the ICA. https://thejns.org/doi/10.3171/CASE25260.