Open Access

Nicole Neubauer, Micol Colosimo, Ralf Becker, Mariangela Kopp, Dorothee Mielke, Nadine Lilla, Philipp Krauss

• Since 2009, navigated transcranial magnetic stimulation (nTMS) is accepted as a diagnostic and therapeutic tool in several neurosurgical applications, particularly to perform functional cortical mapping. However, its use in determining the precise cortical representation of the motor hand area affected by intracranial lesions remains limited. This study aims to asses the extent and functional impact of lateralized brain pathologies on the functional hand area. Methods We performed a retrospective analysis on prospectively collected data of at least 20 neurosurgical patients undergoing bilateral motor nTMS (NEXSTIM NBS5) during clinical routine. Patients were tested following an internal standard protocol after determination of the motor stimulation threshold for each hemisphere. After MRI fusion, we analyzed the size of the suprathreshold hand motor response via electromyography (EMG), minimal motor threshold according to side, and handiness as well as age andSince 2009, navigated transcranial magnetic stimulation (nTMS) is accepted as a diagnostic and therapeutic tool in several neurosurgical applications, particularly to perform functional cortical mapping. However, its use in determining the precise cortical representation of the motor hand area affected by intracranial lesions remains limited. This study aims to asses the extent and functional impact of lateralized brain pathologies on the functional hand area. Methods We performed a retrospective analysis on prospectively collected data of at least 20 neurosurgical patients undergoing bilateral motor nTMS (NEXSTIM NBS5) during clinical routine. Patients were tested following an internal standard protocol after determination of the motor stimulation threshold for each hemisphere. After MRI fusion, we analyzed the size of the suprathreshold hand motor response via electromyography (EMG), minimal motor threshold according to side, and handiness as well as age and pathology. Results Preliminary data suggest that the dominant hemisphere exhibits a larger motor hand area surface and a lower stimulation threshold compared to the non-dominant hemisphere, even in the presence of a lesion. Additionally, lesion-related factors such as edema or hemorrhage may influence EMG responses, potentially altering the expected motor representation patterns. Conclusions Preliminary data suggest differences in motor representation of the hand area according to side and handiness. This study might support the importance of preoperative motor mapping for neurosurgical planning.…