Haptic simulation of neurosurgery interventions.

Disorders of blood circulation in the brain (stroke and cerebral hemorrhage) are among the most frequent causes of death in western industrialized countries. Intracranial aneurysms, one of the main causes of bleeding, are treated with two fundamentally different strategies: In the minimally invasive method called coiling, the aneurysm is filled with a wire coil via a catheter, while in the conventional neurosurgical method (clipping), the skull is opened and one or more titanium clips are placed on the artery, which should clamp the aneurysm from the blood circulation. Since the endovascular procedure is increasingly being used for simple types of aneurysms, only complex aneurysms remain for clipping.

For young neurosurgeons, it is therefore becoming increasingly difficult to find simple situations where they can develop the necessary expertise for complex cases. The operation simulator VIRTUAL ANEURYSM of RISC Software GmbH is designed to provide a solution. It allows the training of clipping interventions in different virtual scenarios. The system is equipped with two haptic input devices with force feedback as well as a stereoscopic display. Several aneurysm geometries with varying degrees of difficulty are available, and the user can choose from a list of over 50 3D-modeled clips of different sizes and shapes.

At the beginning of the training, the user exercises the correct head positioning as well as the optimal positioning of the craniotomy for the respective case. During the actual clipping operation, the simulator constantly detects and responds to collisions between instruments and tissue. The realistic deformation of the blood vessels is calculated and visualized in real time using a specially optimized finite element method on the GPU. The resulting forces are sent to the haptic devices so that the trainee can feel the resistance of the tissue.

A clipping forceps with an openinng-sensor is installed on one of the haptic devices. The opening angle is transmitted to the simulation in real-time. Depending on this elected difficulty, a rupture may also occur, and the surgeon must then stop the bleeding within a predetermined period of time and treat the ruptured aneurysm. After the end of the training, the user can view his/her result from all angles. In order to achieve an objective evaluation of the training, the blood flow through the artery with an anchored aneurysm is calculated. In this way, the induced stenosis and the residual flow into the aneurysm can be estimated, which leads to a final assessment scheme. All training data is stored for each user and can be visualized and compared at any time.

This project was funded by the Upper Austrian State Government and the FFG under the BRIDGE program. Partners were the Kepler Universitätsklinikum Neuromed Campus (NC) Linz, Med Campus III and the German medical device manufacturer Aesculap AG, the world market leader for hand-held surgical instruments.

The prototype of the simulator is undergoing a trial at the KUK Neuromed Campus. Further research activities are planned for a better and more realistic simulation of neurosurgical clipping surgery.

This project was funded by the Upper Austrian State Government and the FFG under the BRIDGE program.

The projects of the Research Unit Medical Informatics are funded by the State of Upper Austria through the Strategic Economic and Research Program “Innovatives OÖ 2020.”