Bilateral internal carotid artery agenesis associated with vertebrobasilar dolichoectasia and acute ischaemic stroke

Bilateral congenital absence of the internal carotid arteries (ICAs) is an exceptionally rare vascular anomaly that profoundly alters cerebral haemodynamic. We describe the case of an elderly woman in her late 60s who presented with acute loss of consciousness and a hypertensive crisis. Neuroimaging revealed complete absence of both ICAs with absent carotid canals, confirming true agenesis, alongside vertebrobasilar dolichoectasia and a two-vessel aortic arch. The anterior circulation was supplied entirely by enlarged posterior communicating arteries. Initial CT demonstrated early ischaemic changes involving less than one-third of the left middle cerebral artery territory, and perfusion imaging identified potentially salvageable penumbra, supporting intravenous thrombolysis. Despite intravenous thrombolysis and intensive care management, the patient's course was complicated by malignant infarction and sepsis, resulting in death. This case underscores the diagnostic importance of recognising congenital ICA agenesis and its association with vertebrobasilar dolichoectasia, which influences cerebrovascular risk, imaging interpretation and acute stroke management.