Endovascular structures of the basilar artery as forms of the basilar nonfusion spectrum

Cerebrovascular diseases are a growing social and clinical problem. The intravascular anatomy of the cerebral circulation remains poorly understood, although an increasing number of endovascular interventions are being conducted. The purpose of this study was to describe intravascular structures in the vertebrobasilar system and to investigate the hemodynamic consequences of their presence. Thirty anatomical specimens of the human brain were analyzed via angioscopy, and the presence of intravascular structures was documented. Additional histological studies were performed. The effect on blood flow was simulated using computational fluid dynamics. In 8 out of 30 cases (26.7%), the following endovascular structures were visualized: 6 strings, one septum, and one chord. The histological structure showed a layered pattern, resembling that of the arterial wall. Blood flow simulations revealed several areas of disturbed flow. Intravascular structures are common in the basilar artery. The reason for their formation is the incomplete fusion of the longitudinal neural arteries, and together with fenestrations, they belong to the basilar nonfusion spectrum. The presence of structures can cause technical difficulties and ischemic complications related to endovascular interventions. Hemodynamic changes caused by endovascular structures can promote atherosclerosis, thromboembolism, narrowing of the pontine arteries and the development of aneurysms.