Article
TMS as a part of multimodal management of safe glioma resection in the motor cortex
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Authors
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M.T. Forster
- Klinik für Neurochirurgie, Universitätsklinikum Frankfurt am Main
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T. Gasser
- Klinik für Neurochirurgie, Universitätsklinikum Frankfurt am Main
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E. Hattingen
- Klinik für Neurochirurgie, Universitätsklinikum Frankfurt am Main
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V. Seifert
- Klinik für Neurochirurgie, Universitätsklinikum Frankfurt am Main
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A. Szelényi
- Klinik für Neurochirurgie, Universitätsklinikum Frankfurt am Main
| Published: | May 20, 2009 |
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Outline
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Objective: Tumours located in the motor cortex pose a challenge to all neurosurgeons. The path between the greatest possible resection and postoperative paresis may be very narrow. For preoperative assessment of eloquent cortical areas fMRI is used, whereas intraoperatively direct cortical stimulation (DCS) is performed.
Navigated transcranial magnetic stimulation (nTMS) is comparable to DCS in activating cortical pyramidal neurons. Thus, for preoperative resection planning of centrally located tumors, it might be more precise compared to fMRI.
Methods: In a prospective series, eight patients (51.6±19y, 2 females) with tumours located in or adjacent to the motor cortex were evaluated for glioma surgery. Preoperatively, fMRI and nTMS were applied for preoperative assessment of the extent of tumour resection. For fMRI acquisition the Wilde intelligence test and semantic-synonym-task were utilized. These data were integrated in the eXimia NBS station (Nexstim Ltd., Finland) for ensuing motor cortex mapping by TMS. Responses from TMS were evaluated by EMG response amplitude and latency and accordingly visualized on the fMRI. In a next step the so modified fMRI was integrated into neuronavigation. During surgery, the coordinates of each DCS site were unambiguously defined and integrated into neuronavigation, too. Finally, the coordinates of stimulation sites, of TMS and of fMRI were compared.
Results: In all patients TMS showed congruence with DCS. In contrast to fMRI, TMS and DCS enabled identification of eloquent cortex within the tumour. Moreover, fMRI consistently visualized a smaller area of functional tissue than defined by TMS and DCS. Safe tumour resection could be performed in all patients of whom none presented new paresis postoperatively.
Conclusions: Tumours located in motor cortex are often generally categorized as unresectable. By usingTMS this opinion may be called into question since it anticipates information usually only enabled by DCS and therefore may show functional tissue beside the tumour. According to our experience, TMS has its place in multimodal functional surgical planning in eloquent cortex surgery.
