Adverse Events Associated with Motor Evoked Potential Monitoring

Abstract

Intraoperative motor evoked potential（MEP）monitoring is generally a safe technique but can inadvertently cause harm. Transcranial electrical stimulation（TES）can cause excitotoxic or thermal injury of the brain or scalp. Direct cortical stimulation may cause electrochemical injury at the electrode-tissue interface. Careful observation and avoidance of excessive electrical stimulation are important to prevent adverse events. Other safety concerns include invasive electrode complications, seizures, arrhythmia, bite injuries, and movement-induced injury. Tongue and lip bite injuries by jaw muscle contractions are the most commonly reported complications during MEP monitoring. Frequent intraoperative checking of the position of the soft bite block and around the mouth is recommended. Movement in the surgical field caused by TES may disturb surgical manipulation. Therefore, the timing of stimulation for MEP monitoring should be selected carefully. Skull defects, cortical lesion, epilepsy, and implanted bioelectric devices are considered to be relative contraindications. Benefits and risks should be considered carefully before MEP monitoring in patients with a relative contraindication. Sharing knowledge about adverse events associated with MEP monitoring and communication among monitorists, surgeons, and anesthesiologists are critical for successful monitoring of MEP and for safety.