Introduction: Better understanding of the mechanisms behind cerebral plasticity, coupled with non-invasive detection of its presence, harbors a huge potential to improve glioma therapy. Our aim was to demonstrate the frequency of plastic reshaping, find patterns behind it, and prove it can be recognized non-invasively using navigated transcranial stimulation (nTMS).
Methods: We used nTMS to map cortical motor representation in 22 patients with gliomas affecting the precentral gyrus immediately pre-op, and 3-42 months post-op. Location changes of the primary motor area, defined as hotspots and map centers of gravity, were measured.
Results: Spatial normalization of nTMS and MRI data showed an average primary motor area shift of 4.7±0.8mm standard error of the mean (SEM) on the mediolateral axis, and 9.7±1.5mm SEM on the anteroposterior axis. Motor-eloquent points tended to shift towards the resection cavity by 4.5±3.6mm SEM if the lesion was anterior to the rolandic region and by 2.6±3.4mm SEM if it was located more posteriorly. Overall, 8 out of 16 (50%) high-grade and 3 out of 6 (50%) low-grade glioma patients showed a functional shift of over 10 mm at the cortical surface level.
Conclusions: Despite the series’ small size, analysis of these data shows impressively that cortical functional reorganization occurs quite frequently. Moreover, nTMS is shown to detect such plastic reorganization non-invasively. However, since tumor- and deficit-related subgroups might show different patterns, multicentric analysis of a larger cohort seems compulsory. This provides further motivation to join our newly founded multicentric international study group.
Patient Care: by the oncological potential of neuroplasticity
Learning Objectives: By the conclusion of this session, participants should be aware of the oncological potential of neuroplasticity