Functional Compression of the Right Internal Carotid Artery by the Hyoid Bone in a Patient with Moyamoya Syndrome and Low Internal Carotid Artery Bifurcation: A Case Report

Background: Functional compression of the internal carotid artery by hyoid bone is a rare but potentially serious condition that can
lead to vascular complications, particularly when coexisting with intracranial vascular abnormalities. This case report describes a 48-
year-old woman with acute cerebral ischemia due to a combination of functional right internal carotid artery compression by the hyoid
bone, low carotid bifurcation, and coexisting Moyamoya syndrome.
Case Report: In this article, we describe the clinical case of a 48-year-old woman who presented with sudden-onset weakness in her
left arm. Imaging studies demonstrated acute ischemia in the territory supplied by the right middle cerebral artery. Further evaluation
with computed tomography angiography revealed compression of the right internal carotid artery by the hyoid bone. However,
additional imaging studies, including digital subtraction angiography and carotid Doppler ultrasound, did not reveal any signs of
internal carotid artery stenosis. This suggested that the compression was functional, occurring only in specific positions of the head or
arms. The patient was also newly diagnosed with Moyamoya syndrome, characterized by progressive stenosis of the intracranial
vessels. Prompt recognition of these findings enabled timely management, including the initiation of antiplatelet therapy.
Conclusion: In cases of acute brain ischemia, it is crucial to consider both intracranial and extracranial vascular conditions. This case
report underscores the significance of identifying anatomical variations in the relationship between the hyoid bone and the internal
carotid artery, as it can lead to arterial compression and potentially trigger acute ischemic strokes, especially in combination with
Moyamoya syndrome. Understanding these anatomical nuances is essential for early diagnosis and appropriate management.