[Internal Carotid Artery Stenosis Associated with Hyoid Bone:Can Hyoid Bone be a Risk Factor for Acute Cerebrovascular Syndrome?].

Eagle syndrome is a well-known disease caused by elongation of the styloid process and/or calcification of the stylohyoid ligament, which interferes with adjacent anatomical structures, giving rise to acute cerebrovascular syndrome(ACVS)and/or pain. Although hyoid bone is also a stylohyoid complex, its association with ACVS is not well known. Thus, we investigated the anatomical relationship between the internal carotid artery(ICA)and the hyoid bone. Between January 2014 and December 2015, three-dimensional computed tomographic angiography(3D-CTA)of the neck was performed for 218 patients. Of the patients, an abnormal anatomical relationship was noted in 10(4.6%)cases. In 5 cases, the ICA was entrapped by the hyoid bone. In 3 cases, the ICA was in contact with or adjusted to the hyoid bone. In 2 cases, the ICA was compressed by the hyoid bone, causing ACVS. In 7 cases, the position and course of the ICA were inward. In 4 of these cases, the hyoid bone was repositioned back to its normal location. Moreover, in 1 case, the course of the ICA was repositioned back to its normal location beside the hyoid bone. The anatomical position of the hyoid bone may vary more than expected and can be a risk factor for ACVS. In particular, in cases of ACVS where the ICA has an inward course, the relationship between the ICA and the hyoid bone should be proactively examined.