Risk stratification by nrTMS language mapping

Abstract

Resecting language-eloquent brain lesions is a major challenge in neurosurgery since we need to weight the risks of worsening the patients' functional integrity and achieving a maximum safe resection. Although relevant functional brain structures can be identified intraoperatively by direct cortical mapping during awake surgery, a preoperative identification of functional anatomy is recommended in order to gauge surgical risks, evaluate resectability, plan the surgical approach, and identify potential starting points for intraoperative stimulation mapping. This improves preoperative patient counseling and intraoperative safety and additionally reduces awake time. Likewise, noninvasive preoperative mapping of language function also improves the care of another (small) subgroup of patients, which is not amendable for awake language mapping or fail language mapping during surgery. This chapter therefore provides an overview on the currently available data of presurgical nTMS language mapping as a tool for risk stratification, identification of hemispheric language dominance, and the general reliability of nTMS language mapping for surgical applications.