Application Of Presurgical Navigated Transcranial Magnetic Stimulation Motor Mapping For Adjuvant Radiotherapy Treatment Planning In Patients With Brain Tumors

Lately navigated transcranial magnetic stimulation (nTMS) has been implemented in the neurosurgical routine to detect motor-eloquent areas for safe and complete resection of high-grad gliomas (HGG). However, in radiotherapy (RT) planning, the primary motor cortex is not respected in target volume delineation. This study evaluates the implementation of nTMS motor mapping for RT planning in patients harbouring motor-eloquent HGGs. nTMS motor maps of 30 patients diagnosed with motor-eloquent HGGs were fused with RT planning and imaging and volumetric modulated RT plans were optimized using nTMS maps as organ at risk (OAR). Doses to nTMS motor maps were evaluated using dose-volume histogramm (DVH) parameters. Mean dose (Dmean) to the nTMS motor maps was 42.3 Gray (Gy) (3.7–61.1 Gy) and was significantly reduced by 14.3% to 37.0 Gy (3.6 - 55.8 Gy, p<0.05) when constraining the dose to nTMS motor areas to 45 Gy. Yet, the dose to the planning total volume (PTV) was not compromised. Even with an additional dose escalation of 70 Gy to the tumor area, nTMS motor maps can be spared by 4.6 +/- 3.5 Gy (12.8%, p<0.05). CONCLUSIONS: nTMS motor maps can be easily implemented in standard RT planning and applied for target contouring in the treatment of HGGs. Doses to motor-eloquent areas can be significantly reduced when considering nTMS motor maps without affecting treatment doses to the PTV. Thus, nTMS could be used as a valuable tool in RT planning.