Aplastic Internal Carotid Artery: A Potentially Catastrophic Vascular Anomaly

Congenital absence of an internal carotid artery (ICA) is a rare vascular anomaly and occurs in less than 0.01% of the population. We report a case of aplastic internal carotid artery in a 34-year-old female. The patient presented to the emergency department with complaints of new-onset involuntary swaying-like movement of her right arm. Brain magnetic resonance imaging showed multifocal tiny areas of acute infarcts in the bilateral frontal, parietal, and left occipital lobes in the watershed distribution. There was no visualization of the flow of the intracranial left internal carotid artery. Follow-up CTA of the head and neck showed a congenital absence of the left internal carotid artery with no evidence of arterial dissection, occlusion, or aneurysm. Obstruction of the internal carotid artery has significant consequences for patients. This effect is amplified if the disruption occurs in the sole anterior blood supply to the parenchyma of the brain, as in this case. In our patient care, imaging was vital to the detection and subsequent treatment with anticoagulation to avoid further cerebral complications, and the patient will now have a better understanding of the increased lifetime risk of further events.