Safety of Transcranial Motor-Evoked Potential Linked Quadripolar Montage

The linked quadripolar montage for transcranial electric motor-evoked potentials (qTceMEP) consists of four stimulation electrodes: two linked anodes and two linked cathodes. This montage has grown in popularity because it can result in a larger compound muscle action potential amplitude compared with the conventional bipolar montage. Despite the increasing number of centers adopting qTceMEP, no studies have investigated patient safety to date. The aim of this study is to evaluate the safety profile of qTceMEP.

A total of 3,806 spine surgeries performed at a single institution using intraoperative transcranial electrical motor-evoked potentials (TceMEP) were reviewed. Among them, 1,196 were performed using bipolar TceMEP, while the remaining 2,610 cases were performed using qTceMEP. The incidence of intraoperative seizure, unexpected cardiac events, bite/oral injuries, and movement-related injuries was compared between the two groups, bipolar TceMEP and qTceMEP. The statistical analysis was performed using MedCalc.

No seizure activity, cardiac anomalies, or adverse events related to intracranial and cardiac implant devices were reported in either group. The incidence of intraoperative oral injuries was 0.4% in the bipolar TceMEP group and 0.5% in the qTceMEP group. The difference in the incidence of oral injuries between the two groups was not statistically significant.

The use of qTceMEP does not increase or decrease a patient's risk of intraoperative injury. Both bipolar TceMEP and qTceMEP are safe, presenting a small incidence of oral injuries and no other adverse side effects.