Non-Invasive Measurement of Cortical Plasticity in Brain Tumour Surgery: A Monocentric Experience of nTMS Mapping and Definition of Cognitive Reshaping Based on Tumour Histological Grade

Background and Objectives: Cortical plasticity assessment using navigated transcranial magnetic stimulation (nTMS) represents a promising non-invasive strategy for predicting reorganisation of cortical circuits in neuro-oncological patients. This study examined how glioma grade influences cognitive network reorganisation by multiparametric analysis. Materials and Methods: We conducted a prospective monocentric study at the Neurosurgical Department in Florence and a comparative analysis of motor (M), language (Ln), calculation (C), and visuo-spatial functions (VS) between patients with low-grade gliomas (LGGs) and high-grade gliomas (HGGs) undergoing pre- and postoperative nTMS mapping (at 5 ± 2, 30 ± 10, and 90 ± 10 days of follow-up). Results: Between January2024 and September 2025, we enrolled 69 patients, and the total number of nTMS mapping procedures was 70: one relapse, (M:F = 345:365), level of scholarship 8–15 years, 21 LGGs, 30 HGGs, 19 non-glial lesions (excluded), left lesions n = 37, right lesions n = 31, bilateral n = 2, bi-hemispheric nTMS = 80%. Considering LGGs and HGGs, the major motor function displacement was obtained in the right hemisphere (Rh; predominantly for HGGs 64 mm vs. LGGs 39 mm), with more restrained displacement in the left hemisphere (Lh; LGGs 20 mm vs. HGGs 21 mm). For Ln, displacement was higher for HGGs (57 mm vs. LGGs 31 mm). However, surprisingly for HGGs in the Lh, the displacement was more significant (60 mm), whereas for LGGs it was major in the Rh (~ 80 mm). For C, displacement for HGGs was 72 mm Lh vs. 48.11 mm Rh, and for LGGs 50 mm Lh vs. 41 mm Rh. Insufficient data were obtained for the network. Qualitative analyses further characterised this reorganisation: motor f. demonstrated reshaping around the primary motor cortex; linguistic f. displaced from temporo-parietal areas to the inferior frontal gyrus; calculation and VS functions reorganised within frontoparietal circuits. The correlation between cognitive results and BPI revealed that higher BPI values were associated with prolonged recovery periods. Nevertheless, functional recovery was achieved in up to 90% of patients across all assessed functions. Conclusions: We propose non-invasively measuring cortical plasticity across different cognitive domains with a quantitative–qualitative framework for assessing functional reorganisation with a multimodal assessment in glioma patients.