Incidental sonographic finding of an extracranial internal carotid artery aneurysm confirmed by CT angiography.

We report a rare case of an extracranial internal carotid artery aneurysm (EICAA) discovered incidentally by color Doppler sonography (CDUS) and confirmed by CT angiography with three-dimensional reconstructions. As both brain MRI and cerebral angiography were normal and the patient remained asymptomatic, he was neither operated on nor stented but was discharged with appropriate antiplatelet therapy. The volume of his EICAA is checked regularly by CDUS.