Evolution of Embolic Agents in Interventional Neuroradiology

The growth in understanding of the pathophysiological relationships between various neurovascular diseases in the past decades has increased the significance and need for endovascular treatment. Consequently, an extraordinary development of different embolic agents was indispensable. The present work first presents the historical milestones in the discovery of various embolic materials used for neurovascular interventions. In the second part, the current endovascular embolization procedures, requiring both liquid and solid embolic agents, are discussed. In some cases and diseases the combination of both may be mandatory. Special emphasis is placed on the consideration needed when choosing appropriate embolic materials, chiefly depending on the goal of the endovascular procedure. Furthermore, the present understanding of the specifics in angioarchitecture and hemodynamics, leading to the most suitable form of access to the vascular lesion, will be covered. Regarding the latter, it is important to note that the aim should always be to achieve optimal superselectivity while being aware of all approaches, ranging from transarterial and transvenous to direct puncture. Finally, based on the limitations of the currently available embolic materials, we present a brief outlook on the future of new liquid and solid embolic agents.