NBS mapping reveals brain plasticity of language function following neurosurgery

HELSINKI, Finland – Feb. 4, 2014 -- There is an overwhelming consensus amongst brain researchers and clinicians that the brain is plastic and that brain function can be significantly re-organized in the individual patient due to the progressive brain disease or in response to brain injury. A medical procedure, such as resection or radiosurgery can also induce reorganization of cortical function. Earlier, Navigated Brain Stimulation (NBS) has been successfully used by clinicians to demonstrate the re-location of motor function following brain surgery in slow-growing brain tumors. Until now, however, plasticity of language function has not been shown.

In a paper "Repeated mapping of cortical language sites by preoperative navigated transcranial magnetic stimulation compared to repeated intraoperative DCS mapping in awake craniotomy" by Professor Meyer´s team at Technische Universität München (TUM), clinicians at the TUM have shown that language function is plastic using Nexstim´s NBS System. By interfering with speech production, the NBS System uses rTMS (repetitive TMS) to map areas of the cortex needed for language.

Although direct cortical stimulation (DCS) is still considered the gold standard for language localization, DCS requires a craniotomy prior to stimulation of the exposed surface of the brain with a bipolar electrode. NBS is a safe, non-invasive procedure that can be used to map language function prior to surgery for planning purposes and also allows for post-operative monitoring of changes in language function localization.

In the study, NBS language mapping was used for the follow-up of three patients undergoing repeated awake surgeries for treatment of language-eloquent gliomas. The awake surgeries and language mappings by both NBS and DCS were repeated 7, 10, and 15 months subsequent to the initial resection.

A good correlation between the pre-surgical NBS language mapping and intraoperative DCS results was observed in all three patients for the initial surgery. However, the initial NBS and DCS findings only corresponded with the results obtained from the second NBS mapping and awake surgery - at 7 months - in one out of the three patients. In their conclusion, the clinicians state that these NBS and DCS data suggest changes of language organization as a consequence of brain plasticity in the other two patients in the study.