BACKGROUND: Navigated transcranial magnetic stimulation (nTMS) is increasingly used in presurgical brain mapping. Preoperative nTMS results correlate well with direct cortical stimulation (DCS) data in the identification of the primary motor cortex. Repetitive nTMS can also be used for mapping of speech-sensitive cortical areas. OBJECTIVE: The current cohort study compares the safety and effectiveness of preoperative nTMS with DCS mapping during awake surgery for the identification of language areas in patients with left-sided cerebral lesions. METHODS: Twenty patients with tumors in or close to left-sided language eloquent regions were examined by repetitive nTMS before surgery. During awake surgery, language-eloquent cortex was identified by DCS. nTMS results were compared for accuracy and reliability with regard to DCS by projecting both results into the cortical parcellation system. RESULTS: Presurgical nTMS maps showed an overall sensitivity of 90.2%, specificity of 23.8%, positive predictive value of 35.6%, and negative predictive value of 83.9% compared with DCS. For the anatomic Broca's area, the corresponding values were a sensitivity of 100%, specificity of 13.0%, positive predictive value of 56.5%, and negative predictive value of 100%, respectively. CONCLUSION: Good overall correlation between repetitive nTMS and DCS was observed, particularly with regard to negatively mapped regions. Noninvasive inhibition mapping with nTMS is evolving as a valuable tool for preoperative mapping of language areas. Yet its low specificity in posterior language areas in the current study necessitates further research to refine the methodology.

nTMS provides crucial data for preoperative planning and surgical resection of tumors involving essential motor areas. Expanding surgical indications and extent of resection based on nTMS enables more patients to undergo surgery and might lead to better neurological outcomes and higher survival rates in brain tumor patients. The impact of this study should go far beyond the neurosurgical community because it could fundamentally improve treatment and outcome, and its results will likely change clinical practice.

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Background Augmented reality (AR) has the potential to support complex neurosurgical interventions by including visual information seamlessly. This study examines intraoperative visualization parameters and clinical impact of AR in brain tumor surgery. Methods Fifty-five intracranial lesions, operated either with AR-navigated microscope (n = 39) or conventional neuronavigation (n = 16) after randomization, have been included prospectively. Surgical resection time, duration/type/mode of AR, displayed objects (n, type), pointer-based navigation checks (n), usability of control, quality indicators, and overall surgical usefulness of AR have been assessed. Results AR display has been used in 44.4% of resection time. Predominant AR type was navigation view (75.7%), followed by target volumes (20.1%). Predominant AR mode was picture-in-picture (PiP) (72.5%), followed by 23.3% overlay display. In 43.6% of cases, vision of important anatomical structures has been partially or entirely blocked by AR information. A total of 7.7% of cases used MRI navigation only, 30.8% used one, 23.1% used two, and 38.5% used three or more object segmentations in AR navigation. A total of 66.7% of surgeons found AR visualization helpful in the individual surgical case. AR depth information and accuracy have been rated acceptable (median 3.0 vs. median 5.0 in conventional neuronavigation). The mean utilization of the navigation pointer was 2.6 × /resection hour (AR) vs. 9.7 × /resection hour (neuronavigation); navigation effort was significantly reduced in AR (P < 0.001). Conclusions The main benefit of HUD-based AR visualization in brain tumor surgery is the integrated continuous display allowing for pointer-less navigation. Navigation view (PiP) provides the highest usability while blocking the operative field less frequently. Visualization quality will benefit from improvements in registration accuracy and depth impression. German clinical trials registration number. DRKS00016955.

Background We introduce a user-friendly, standardized protocol for tractography of the major language fiber bundles. Method The introduced method uses dMRI images for tractography whereas the ROI definition is based on structural T1 MPRAGE MRI templates, without normalization to MNI space. ROIs for five language-relevant fiber bundles were visualized on an axial, coronal, or sagittal view of T1 MPRAGE images. The ROIs were defined based upon the tracts’ obligatory pathways, derived from literature and own experiences in peritumoral tractography. Results The resulting guideline was evaluated for each fiber bundle in ten healthy subjects and ten patients by one expert and three raters. Overall, 300 ROIs were evaluated and compared. The targeted language fiber bundles could be tracked in 88% of the ROI pairs, based on the raters’ result blinded ROI placements. The evaluation indicated that the precision of the ROIs did not relate to the varying experience of the raters. Conclusions Our guideline introduces a standardized language tractography method for routine preoperative workup and for research contexts. The ROI placement guideline based on easy-to-identify anatomical landmarks proved to be user-friendly and accurate, also in inexperienced test persons.