Changing the clinical course of glioma patients by preoperative motor mapping with navigated transcranial magnetic brain stimulation

Sandro M Krieg, Nico Sollmann, Thomas Obermueller, Jamil Sabih, Lucia Bulubas, Chiara Negwer, Tobias Moser, Doris Droese, Tobias Boeckh-Behrens, Florian Ringel, Bernhard Meyer

Mapping of the motor cortex by navigated transcranial magnetic stimulation (nTMS) can be used for preoperative planning in brain tumor patients. Just recently, it has been proven to actually change outcomes by increasing the rate of gross total resection (GTR) and by reducing the surgery-related rate of paresis significantly in cohorts of patients suffering from different entities of intracranial lesions. Yet, we also need data that shows whether these changes also lead to a changed clinical course, and can also be achieved specifically in high-grade glioma (HGG) patients. We prospectively enrolled 70 patients with supratentorial motor eloquently located HGG undergoing preoperative nTMS (2010-2014) and matched these patients with 70 HGG patients who did not undergo preoperative nTMS (2007-2010). On average, the overall size of the craniotomy was significantly smaller for nTMS patients when compared to the non-nTMS group (nTMS: 25.3 ± 9.7 cm(2); non-nTMS: 30.8 ± 13.2 cm(2); p = 0.0058). Furthermore, residual tumor tissue (nTMS: 34.3%; non-nTMS: 54.3%; p = 0.0172) and unexpected tumor residuals (nTMS: 15.7%; non-nTMS: 32.9%; p = 0.0180) were less frequent in nTMS patients. Regarding the further clinical course, median inpatient stay was 12 days for the nTMS and 14 days for the non-nTMS group (nTMS: CI 10.5 - 13.5 days; non-nTMS: CI 11.6 - 16.4 days; p = 0.0446). 60.0% of patients of the nTMS group and 54.3% of patients of the non-nTMS group were eligible for postoperative chemotherapy (OR 1.2630, CI 0.6458 - 2.4710, p = 0.4945), while 67.1% of nTMS patients and 48.6% of non-nTMS patients received radiotherapy (OR 2.1640, CI 1.0910 - 4.2910, p = 0.0261). Moreover, 3, 6, and 9 months survival was significantly better in the nTMS group (p = 0.0298, p = 0.0015, and p = 0.0167). With the limitations of this study in mind, our data show that HGG patients might benefit from preoperative nTMS mapping.