gms | German Medical Science

Objective: Language mapping by repetitive navigated transcranial magnetic stimulation (rTMS) is used for resection planning in patients suffering from brain lesions within regions known to be involved in language function. Yet, we also need data that show whether preoperative rTMS for language mapping also has an impact on the patients' clinical course and functional outcomes as it was proved for motor mapping.

Method: We enrolled 25 patients with language eloquently located brain lesions undergoing preoperative rTMS language mapping (GROUP 1, 2011-2013) with mapping results not being available for the surgeon, and matched these patients with 25 subjects, who also underwent preoperative rTMS (GROUP 2, 2013-2014), but mapping results were taken into account during awake mapping and tumor resection via implementation into the neuronavigation system. In addition, cortical language maps were generated by analyzing preoperative rTMS data.

Results: Mean craniotomy sizes were significantly smaller in patients of GROUP 2 (GROUP 1 vs. GROUP 2: 50.1 ± 16.8 cm² vs. 41.6 ± 10.4 cm², p=0.0373), and postoperative language deficits were found significantly more often in patients of GROUP 1 (p=0.0153), although preoperative language status did not differ between groups (p=0.7576). In addition, there was a trend towards less unexpected tumor residuals (GROUP 1 vs. GROUP 2: 32.0% vs. 16.0%, p=0.1853), shorter surgery duration (240.3 ± 53.2 min. vs. 215.5 ± 48.5 min., p=0.0914), and higher postoperative KPS scores (80 vs. 90, p=0.2102) in GROUP 2 patients.

Conclusions: In general, the clinical course and functional outcomes of patients suffering from brain tumors may be improved by preoperative rTMS language mapping. Furthermore, reliable and precise language maps can be generated by rTMS in brain tumor patients, and this approach has once again proven to be safe, effective, and well-tolerable for the individual subject. However, more patients have to be enrolled for more conclusive data.