Differentiation Between Internal Carotid Artery Hypoplasia and Acquired Narrowing by Neurovascular Ultrasound: Case Series and Literature Review

Uniformly narrowed internal carotid artery (ICA) without proximal steno-occlusion or parietal anomalies is often subject to misdiagnosis due to lack of awareness. We combined our experiences of 4 cases with 29 previously published cases to form a retrospective series including 18 cases of ICA hypoplasia and 15 cases of ICA acquired narrowing. The ultrasonic manifestations of ICA acquired narrowing and ICA hypoplasia are extremely similar, but narrowed ICA without intracranial occlusion or bottle-neck-sign highly indicates ICA hypoplasia, whereas moyamoya vessels favor ICA acquired narrowing, thus promoting the understanding of and discriminability between the two on neurovascular ultrasound.