• Thomas Picht, Juliane Schulz, and Peter Vajkoczy.
• Department of Neurosurgery, Charité University Hospital, Berlin, Germany, thomas.picht@charite.de.
• Acta Neurochir (Wien). 2013 Oct 1; 155 (10): 1813-21.

BackgroundResection is recommended for low-grade gliomas, but often it is not performed if the tumor is suspected of invading the primary motor cortex. The study aim is to assess what influence preoperative navigated transcranial magnetic stimulation (nTMS) has on the treatment strategy and clinical outcome for suspected low-grade gliomas in presumed motor eloquent location.MethodsThis paper reports on all our patients with gliomas in the primary motor cortex that were non-enhancing on MRI, since we began using nTMS (n = 11). For the comparison group, we identified the 11 most recent such patients just before we started using nTMS.ResultsExact delineation of motor functional versus non-functional cortical tissue was provided by nTMS in all cases, also within the area of altered FLAIR signal. In 6 out of 11 cases, the nTMS mapping result changed the treatment plan towards early and more extensive resection. Only one nTMS patient had another seizure within the follow-up period, whereas four patients in the comparison group had further seizures. In the nTMS group, 1 of 4 patients with pre-op neurological deficits improved by one year; whereas the comparison group had increased neurological deficits in 3 of the 8 patients not having surgery. The median (range) change of tumor volume from baseline to 1 year was -83 % (-67 % to -100 %) in the nTMS group, but +12 % (+40 % to -56 %) in the comparison group (p < 0.001).ConclusionsnTMS provides accurate motor mapping results also in infiltrative gliomas and enables more frequent and more extensive surgical resection of non-enhancing gliomas in or near the primary motor cortex. The substantial differences observed here in neurological and oncological outcomes suggest that further comparative research is warranted.

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