Integration of multimodality imaging and surgical navigation in the management of patients with refractory epilepsy. A pilot study using a new minimally invasive reference and head-fixation system

To review the experience with a new system (VBH system) for minimally invasive frameless stereotactic guidance, acting as a common platform to provide multimodal image integration and surgical navigation in a consecutive series of 25 patients who underwent surgery for drug-resistant seizures. The usefulness of the VBH system for integrating all images to produce one dataset and for intraoperative instrument guidance and navigation was judged semiquantitatively in a three-tiered scale (+, ++, +++). Seizure outcome was classified according to Engel. The presurgical evaluation extended over 21.2 months (mean). A total of 141 registrations of images were performed (mean 5.6 per patient, range: 2 to 16). In 19 (76%) of 25 patients structural data fused with functional data were used for the presurgical workup. Six patients proceeded directly to navigated resection. Nineteen patients (76%) underwent invasive recording, of whom 13 underwent resective surgery. In seven patients (28%) the combination of multimodal image fusion and intra-operative stereotactic guidance was judged essential (+++) to remove the epileptogenic zone. Integration of all images to form one dataset was essential (+++) for decision making in 15 and helpful (++) in 4 patients (overall 76% of patients). Intraoperative use of frameless neuronavigation was essential (+++) in ten and helpful (++) in all remaining patients. Eighty percent of the patients achieved satisfactory seizure outcome after 1 year. The VBH system is a safe and effective non-invasive tool for repetitive imaging, multimodal image fusion and frameless stereotactic surgical navigation in candidates for epilepsy surgery.