Clinical implications of false-negative and false-positive intraoperative transcranial motor evoked potentials in brain tumor surgery.

Intraoperative monitoring of transcranial motor-evoked potentials (tc-MEPs) is widely used to detect disturbances of the motor function during brain tumor surgery. We analyzed false-positive and false-negative tc-MEP findings in consecutive institutional brain tumor surgery cases. A total of 342 patients who underwent brain tumor surgery with tc-MEP monitoring between January 2018 and September 2025 were retrospectively identified and analyzed. Intraoperative tc-MEP findings were compared with postoperative motor outcomes to assess concordance and discordance. False-positive and false-negative tc-MEP findings were defined based on the presence or absence of postoperative motor deficits during the immediate postoperative period and at 1 and 3 months after surgery. The cohort consisted of 170 men (49.7%) and 172 women (50.3%), with a median age of 60 years. Meningioma was the most common pathology, followed by glioma and metastatic brain tumors. Overall, 324 patients (94.7%) showed concordance between intraoperative tc-MEP findings and postoperative motor outcomes. Discordant findings were observed in 18 patients (5.26%), including 10 false-positive cases (2.92%) and 8 false-negative cases (2.34%). Exploratory analyses revealed that peri-rolandic tumor location was significantly associated with false-negative tc-MEP findings, whereas no clinical or tumor-related factors were significantly associated with false-positive events. tc-MEP monitoring demonstrated a high concordance rate with postoperative motor outcomes in brain tumor surgery. False-positive and false-negative findings occurred infrequently and were influenced by tumor location and perioperative factors.