Dear ladies and gentlemen, dear chairman, thank you for giving me the opportunity to present the results of our comparative cohort study on the functional outcome after pre- versus intraoperative language mapping for glioma resection and the evaluation of a classification system for language eloquence. As all of you know, a considerable number of gliomas requires the resection of language eloquent tumors via direct electrical stimulation during awake rheumatomy. On the other hand, we were already able to show that language eloquent gliomas can be resected purely based on navigated repetitive transcranial magnetic stimulation data as mapped preoperatively. The objectives of the present study were on the one hand to analyze the outcomes after preoperative NRTMS-based and intraoperative DES-based glioma resection in a large cohort, and on the other hand to introduce a new classification of language eloquence due to the necessity of making glioma locations comparable. We therefore enrolled 100 patients who underwent NRTMS-based glioma resection between March 2015 and May 2019, and during the same period we enrolled 47 patients who underwent DES-based glioma resection during awake rheumatomy. We compared these two groups regarding the clinical and radiological outcome parameters, which were measured preoperatively, postoperatively, and at three months follow-up. The new classification for language eloquence, which was developed to make glioma locations comparable, was based on our personal experience and the literature which was published on the location of language eloquence based on DES mappings. To allocate patients to one of the two groups, we followed our standard protocol when patients with language eloquent brain lesions come to our department. We first performed an NRTMS language mapping and looked for language positive sites in terms of an NRTMS language mapping within the lesion. If there were language positive sites in terms of an NRTMS language mapping within the lesion, we resected the tumor under DES language mapping during awake craniotomy, and if there were no language positive sites within the lesion, the resection was performed purely based on an NRTMS language mapping. For the comparison of tumor locations, we developed this new classification system for language eloquence. We separated it into high, moderate, and low, looked for the tumor location on a cortical and a subcortical level, and we looked for the patient's history regarding clinical aspects of language eloquence. So each patient received points for cortical language eloquence, subcortical language eloquence, and clinical language eloquence, and the points of each of these three gradings were summarized into the final grading. For the comparison of clinical outcomes between the two groups, we did not find statistically significant differences. There was a higher percentage of transient postoperative language deficits in the awake group, but without significance. Regarding the results for the extent of resection between the two groups, we found more gross total resections in the NRTMS group and more subtotal resections in the awake group, and these results were statistically significant. Regarding the summarized points of tumor locations within the NRTMS and the awake group, we found higher points in the awake group than in the NRTMS group. Nevertheless, we still found tumor locations with high points in patients who underwent tumor resection purely based on NRTMS language mapping. And regarding the final grading, of course, there were more highly language eloquent tumors with regards to the cortical and subcortical grading within the awake group, but still highly cortical and subcortical tumor locations within the NRTMS group. Based on these results, we can conclude that resecting language eloquent gliomas purely based on NRTMS data is feasible if the clinical workflow is followed, and the proposed classification for language eloquence makes language eloquent tumors comparable, as shown by its correlation with functional and radiological outcomes. Thank you for your attention.

preoperative navigated repetitive transcranial magnetic stimulation

intraoperative direct electrical stimulation

glioma resection

language mapping

classification system