The Value of Preoperative Planning Based on Navigated Transcranical Magnetic Stimulation for Surgical Treatment of Brain Metastases Located in the Perisylvian Area

Background: Brain metastases are the most common neoplasms in adults. When brain metastases are located in eloquent areas, their treatment still seems controversial and not clearly defined. It is therefore essential to provide correct preoperative planning to better define extension and characterization of brain metastasis. Methods: We retrospectively looked for the tumor database of our institution, patients with single brain metastasis, located in the sylvian area, who underwent resection with the support of intraoperative neurophysiologic monitoring between 2008 and 2018. Results: We retrieved data for 30 adults, each with a single brain metastasis that was located in the sylvian area, including the insula and the lower portion of the motor cortex. Neuronavigation and the intraoperative visualization of the navigated transcranial magnetic stimulation–based reconstruction of functional networks were used to delineate the ideal trajectory toward the lesion. The Karnofsky Performance Status significantly improved in the postoperative period. Conclusions: The correct planning of brain metastasis allows more secure removal of the neoplastic lesion, avoiding and/or reducing the appearance of neurologic deficits. Navigated transcranial magnetic stimulation represents a new method that can promote a more complete and safer resection of the metastatic lesion in eloquent areas. An optimal surgical result, in the absence of postoperative neurologic deficits, allows the patient to undertake adjuvant therapy able to prolong survival.