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Preoperative motor mapping by navigated transcranial magnetic brain stimulation improves outcome for motor eloquent lesions

12 February 2014

HELSINKI, Finland—Feb. 12, 2014--Nexstim is pleased to announce the publication of the first large-scale comparative study on patient outcomes following neurosurgery guided by Navigated Brain Stimulation (NBS) in challenging cases. The Nexstim NBS System is the first and only FDA-cleared and CE-marked nTMS mapping device available for clinical use. This new study "Preoperative motor mapping by navigated transcranial magnetic brain stimulation improves outcome for motor eloquent lesions" authored by Dr. Sandro Krieg et al. from the Klinikum rechts der Isar, Technische Universität München (TUM), Germany adds to earlier evidence published by Dr. Thomas Picht et al. (Charité-Universitätsmedizin Berlin, Germany) showing that presurgical NBS mapping enabled more frequent and more extensive surgical resection of low-grade glioma tumors.

In this new study, a prospectively enrolled cohort of 100 patients with lesions located in motor eloquent areas were preoperatively mapped by nTMS following adoption of the NBS System in 2010. The 100 patients were matched with a control group of 100 patients who had been operated on in the 3 years prior to 2010 - before the availability of NBS mapping at TUM.

The group of patients preoperatively mapped by NBS showed a significantly lower rate of residual tumor, as determined by postoperative MRI scanning. On long-term follow-up, 12% of the patients in the nTMS group had improved motor function, compared to only 1% of the patients in the control group. Moreover, fewer patients mapped by NBS showed deteriorated motor function postoperatively compared to the control group. With regard to surgical technique, NBS mapping enabled smaller craniotomies.

As part of their conclusions, the authors stated that this study increases the level of evidence for preoperative motor mapping by nTMS and that they therefore strongly advocate nTMS to become increasingly used for presurgical mapping of rolandic lesions in the brain. 

In the article, the authors also state that, "nTMS, with comparably easy and cheap availability, represents a remarkable option for non-invasive mapping because it is also based on MEPs via neuronal activation and therefore has a close relationship to DCS (direct cortical stimulation), which is widely used by neurosurgeons. Navigated TMS can be performed in an awake patient and allows surgical planning already at the state of indication."

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