gms | German Medical Science

Objective: Increased usage of neuronavigation systems have led to the authors’ experience, that definitive planning of craniotomy and skin incision placement is often decided after referencing of the navigation system in the OR. In times of drastic reduction of working time of hospital physicians in compliance with EU rules and overcrowded outpatient clinics, neurosurgeons face a time management challenge that results in less time being spent on preoperative planning. We present our experiences using a self-developed bone removal plug-in to plan skin incision and minimalinvasive craniotomy in revascularization surgery and its validation through transdural ICGangiography.

Method: Based on the previously presented 5-step algorithm called Maximum-Minimal-Protocol, a simple virtual bone removal tool has been developed in cooperation with the Vienna Technical University, Institute of Computer Graphics, as a plug-in for the 64-bit, FDA cleared version of the OsiriX software (Pixmeo, Geneva, Switzerland), an open source medical image processing software and DICOM viewer. By reconstructing VR models of STA (donor) and MCA (recipient) branches in preoperative CT-A scans, an individually tailored approach was planned with a „1-click“ option, measured and transferred to the patient skin before final positioning. Before dural opening, validation of the preoperatively planned recipient artery was performed by indocyanine green video-angiography (ICG-VA).

Results: We present our series of the first ten consecutive patients undergoing revascularization surgery (EC-IC bypass, indirect revascularization for Moya-Moya) under Maximum-Minimal-Protocol planning. In all cases, preoperative identification and segmentation of donor/ recipient vessels and exact placement of minimally-invasive craniotomy with our bone removal plug-in took <2min. The transfer and plot of the measured coordinates and vessels on patient skin in the OR lasted less than 60sec and proved in 100% to be remarkably accurate, as the validation through transdural ICG-VA and post-operative CT-A scans demonstrated.

Conclusions: We present our promising and validated first experiences planning and simulating minimalinvasive approaches in EC-IC bypass surgery with a newly developed bone removal software tool. This tool – in combination with the Maximum-Minimal-Protocol – circumvents the necessity for neuronavigation in the cases described above and guarantees a maximum of time- (and therefore cost-) efficiency in the OR.