Open Access

Tammam Abboud, Maximilian Stein, David Wasilewski, Kathleen Seidel, Arthur Wagner, Katharina Faust, Florian Ringel, Dorothee Mielke, Bernhard Meyer, Veit Rohde, Andrea Szelenyi

• Intraoperative monitoring of motor-evoked potentials (MEPs) during resection of supratentorial brain tumors under general anesthesia is commonly performed using either transcranial electrical stimulation via scalp electrodes (TES) or direct cortical stimulation via a strip electrode placed on the precentral gyrus (DCS). To date, evidence favoring one method over the other is lacking. Methods: TRANSEKT is a multicenter, randomized, double-blind, exploratory parallel-group trial conducted at six neurosurgical centers in Germany and Switzerland. Adult patients with supratentorial tumors adjacent to the corticospinal tract and no or mild preoperative paresis were randomized to intraoperative monitoring with TES-MEP or DCS-MEP. A bihemispheric threshold criterion was applied for TES-MEP monitoring, whereas an amplitude-based criterion was used for DCS-MEP. The primary endpoint was deterioration of motor function at discharge or 7 days after surgery, assessed using the Medical ResearchIntraoperative monitoring of motor-evoked potentials (MEPs) during resection of supratentorial brain tumors under general anesthesia is commonly performed using either transcranial electrical stimulation via scalp electrodes (TES) or direct cortical stimulation via a strip electrode placed on the precentral gyrus (DCS). To date, evidence favoring one method over the other is lacking. Methods: TRANSEKT is a multicenter, randomized, double-blind, exploratory parallel-group trial conducted at six neurosurgical centers in Germany and Switzerland. Adult patients with supratentorial tumors adjacent to the corticospinal tract and no or mild preoperative paresis were randomized to intraoperative monitoring with TES-MEP or DCS-MEP. A bihemispheric threshold criterion was applied for TES-MEP monitoring, whereas an amplitude-based criterion was used for DCS-MEP. The primary endpoint was deterioration of motor function at discharge or 7 days after surgery, assessed using the Medical Research Council scale. Secondary endpoints included predictive accuracy of MEP monitoring, extent of tumor resection, and safety outcomes. Results: A total of 137 patients were randomized and 114 patients were included in the final analysis (DCS n = 54; TES n = 60) with a dropout rate of 17%. Mean age was 60 years and 56% of patients were male. Postoperative deterioration of motor function occurred in 13/54 patients (24%) in the DCS group and in 12/60 patients (20%) in the TES group (p = 0.6). Sensitivity for predicting postoperative motor deficits was comparable between techniques (DCS 44%, TES 29%; p = 0.399), while specificity was high in both groups and non-inferior for TES compared with DCS (DCS 86%, TES 94%; p = 0.021). Residual tumor was detected in 33% of patients in the DCS group and in 30% in the TES group, with no significant difference between groups (p = 0.63). Intraoperative seizures occurred in 4/114 cases (3.5%). Three-month mortality was 16%, with one death directly related to surgery. Conclusions: Preliminary results of the TRANSEKT trial demonstrate no significant difference between TES-MEP and DCS-MEP regarding postoperative motor deterioration or extent of tumor resection. Superiority of one monitoring technique over the other could not be confirmed, supporting individualized technique selection based on surgical context and institutional expertise.…