A wide-necked extracranial internal carotid artery saccular aneurysm with ipsilateral proximal compression.

Extracranial internal carotid artery aneurysms (EICAA) are rare and can elicit various neurologic symptoms. Here, we present a case of a saccular EICAA compressing its proximal parent internal carotid artery (ICA). Ultrasonography demonstrated the proximal ICA stenosis and the "tardus-parvus" Doppler waveform downstream. The patient underwent aneurysmectomy and graft interposition. The histologic analysis highly supported an atypical fibromuscular dysplasia. Although this patient only showed a neck mass, the reduced ipsilateral cerebral blood supply was a potential cause for neurologic symptoms. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:116-120, 2017.