Recent advances in cerebrovascular simulation and neuronavigation for the optimization of intracranial aneurysm clipping.

Endovascular treatment of intracranial aneurysms (IAs) has improved to the extent that in some instances such an approach has now become safer than surgery. This has dramatically changed clinical practice by reducing the volume and increasing the complexity of IAs referred for open surgical treatment. We review the simulation techniques and dedicated vascular neuronavigation systems that have been developed to maintain the quality of aneurysm clipping in this context. Simulation of surgical approaches was made possible by the introduction of high-resolution 3D imaging techniques such as three-dimensional CT angiography (3D-CTA) and three-dimensional digital subtraction angiography (3D-DSA), enabling reproduction of the craniotomy and rotation of the vascular tree according to the orientation of the operative microscope. A virtual simulator for compiling such data, the Dextroscope®, is now available for this purpose. Simulation of final clipping has been investigated through virtual or physical models, enabling anticipation of aneurysm deformation during clip application and selection of the appropriate clip(s) in terms of number, size, shape and orientation. To improve surgical dissection guidance, specific cerebrovascular neuronavigation procedures have been developed based on 3D-CTA or 3D-DSA. These help make the operation secure by accurately predicting the location and orientation of an aneurysm within its parenchymal and vascular environment. Future simulators dedicated to cerebrovascular procedures will need to integrate representation of the brain surface and biomechanical modeling of brain and aneurysm wall deformation under retraction or during clipping. They should contribute to training and maintenance of surgical skills, thereby optimizing the quality of surgical treatment in this field.