LAUSR

PURPOSE we describe the integrated use of a neuronavigation-guided system for frameless stereotaxy (Vario-Guide, BrainLAB AG, Germany) with the intraoperative MRI (iMRI) and 5-aminolevulinic acid (5-ALA), observing the advantages and drawbacks that these tools together can have in the treatment of various types of intracerebral lesion. METHODS After skin incision, creation of a burr hole at the entry point and dura opening, the VarioGuide procedure is started. Initially, the wizard software demands positioning of the stereotactic arm over the burr hole and provides feedback upon correct position. The procedure is performed in iMRI theater furnished of a surgical microscope (Kinevo, Zeiss) supplied with a violet-blue excitation light for 5-ALA fluorescence. At the end of the surgery an iMRI scan is performed. We present two exemplary cases to describe the application and workflow of these tools. RESULTS When used for traditional biopsy the possibility to perform a new iMRI scan may be of paramount importance: the brain shift can be compensated and an alternative trajectory can be calculated based on the new images and fiber tracking reconstruction. The fluorescence of the tissue sample examined under microscope filter gave immediate information about the nature of the lesion with the possibility to convert the procedure to an open craniotomy and to remove the tumor. CONCLUSION The combination of a frameless stereotactic system with iMRI and 5-ALA shows benefits in terms of safety and precision. Moreover, these tools were also used to simplify tumor removal after the simple biopsy widening the spectrum of indications.