gms | German Medical Science

Objective: The intraoperative definition of tumour margins especially during the extirpation of low grade or irradiated gliomas can be quite difficult. This can be facilitated with the use of a neuronavigation system. Nevertheless, the possible development of an intraoperative brain shift is a drawback in using this technique resulting in the continuous search for new methods for better brain shift control.

Methods: This technique was developed using a BrainLab neuronavigation system. In the preoperative planning software several trajectories were placed at the tumour margins on T1-weighted MR images. Right after craniotomy ventricular catheters were placed along the predefined trajectories using the neuronavigation pointer after a 5mm dural incision has been made. The position of the placed catheters will be visualized on-line using a registered ultrasound probe. With repeated intraoperative use of the navigated ultrasound, a partial control of the developed brain shift can be achieved. With the visualization of the catheters at the resection wall, the preoperatively defined target points have been reached.

Results: 13 patients with low grade, high grade or irradiated gliomas have been operated using the described technique. In one case with a recurrent grade II glioma incidentally the accuracy of the catheter placement could be verified. In this case the recurrent tumour was located inside the previous resection cavity surrounded by a small layer of CSF. During the operation the catheter could be found exactly at this border. The use of this technique facilitated the intraoperative orientation despite the development of an intraoperative brain shift.

Conclusions: The technique of catheter-guided neuronavigation allows partial control of an intraoperatively developed brain shift. Algorithms to superimpose on-line acquired ultrasound information on preoperatively defined 3D objects have to be developed.