Multiple basilar trunk aneurysms and bilateral internal carotid artery hypoplasia

We describe a case of a 32-year-old woman with bilateral hypoplastic internal carotid arteries who presented with subarachnoid haemorrhage and was found to have two basilar trunk aneurysms. Carotid angiography showed that both internal carotid arteries were narrowed at their origin and terminated at the cervical segment. Vertebral angiography demonstrated a dilated vertebrobasilar system which supplied sufficient blood flow for both cerebral hemispheres through the posterior communicating arteries. The patient was successfully treated by multiple operations.