BackgroundVertebrobasilar dolichoectasia (VBD) is a rare cerebrovascular disorder. The natural history of patients with VBD is generally poor, and current treatments do not appear to provide significant clinical benefit. Therefore, understanding the underlying mechanisms of VBD and implementing appropriate strategies in advance are particularly important.Case presentationIn the first case, a 15-year-old boy initially presented in July 2020 with recurrent mild nausea and vomiting. He was diagnosed with left internal carotid artery (ICA) occlusion secondary to a giant fusiform aneurysm, along with a cerebellar arachnoid cyst. The patient received conservative treatment but did not adhere to the recommendation for regular follow-up. In August 2023, he developed hydrocephalus and severe brainstem compression caused by VBD. Ventriculoperitoneal (V-P) shunting failed to prevent rapid clinical deterioration, which eventually led to fatal intracranial hemorrhage. The second case involved a 9-year-old boy who initially presented in June 2013 with hydrocephalus and underwent V-P shunting. In June 2020, he was diagnosed with right ICA dolichoectasia during an evaluation for neck discomfort and subsequently underwent ligation of the right ICA. In March 2022, he experienced an acute onset of altered consciousness, and neuroimaging confirmed brainstem compression due to VBD. Considering the high anesthetic risk and the limited potential benefit of further surgical intervention, treatment was withdrawn, and the patient ultimately died of brainstem infarction.ConclusionsThese cases highlight the importance of close monitoring in pediatric patients with ICA occlusion, given the associated risk of VBD. Further research into the pathogenesis of VBD, particularly in pediatric patients, is essential to develop more effective preventive and therapeutic strategies.