[Navigated transcranial magnetic stimulation for preoperative mapping of the eloquent cortex]

Brain tumor surgery in functionally relevant areas is particularly challenging. Preoperative functional mapping with navigated transcranial magnetic stimulation (TMS) was introduced into the clinical routine in 2009 and since then has seen widespread adoption.Accuracy and consistency of TMS motor and language mapping and its clinical relevance.Analysis of published scientific papers and discussion of the findings.Positive (i.e. motor responses are elicited) and negative cortical points for TMS motor mapping can be used for treatment planning and intraoperative decision making. Language mapping points (disruption of language function) positive in TMS can support treatment planning but should be confirmed intraoperatively with direct electrical stimulation. Negative TMS language mapping (language functions are not disrupted) correlates well with the gold standard of intraoperative testing. Recent studies reported improved treatment outcome after preoperative TMS mapping.Patients suffering from brain tumors in eloquent locations should be counseled based on individual functional mapping data before surgery and TMS is a valid non-invasive methodology which can provide such functional mapping.