Analysis of Intraoperative Motor Evoked Potential Changes and Surgical Interventions in 513 Pediatric Spine Surgeries.

PURPOSE (1) To determine probabilities of immediate postoperative new motor deficits after no, reversible, and irreversible motor evoked potentials (MEP) deteriorations and (2) to calculate the same outcome considering whether MEP deteriorations were followed by surgical interventions in the absence of confounding factors. METHODS We analyzed MEPs from 513 surgeries. Four-limb MEPs were evoked by transcranial electrical stimulation. Baseline recordings were obtained before skin incision and updated before instrumentation. Motor evoked potentials deteriorations were considered significant whenever they showed a persistent, reversible, or irreversible amplitude decrease of >80% of the baseline values. RESULTS Nine patients showed postoperative new motor deficits. Probabilities of postoperative new motor deficits were null, 2.8%, and 36.8% with no, reversible, and irreversible MEP deteriorations, respectively. The risk of immediate postoperative new motor deficits was significantly lower (P = 0.0002) in reversible MEP compared with irreversible MEP deteriorations. In patients showing reversible/irreversible MEP deteriorations in the absence of confounding factors, surgical interventions compared with nonsurgical interventions significantly decreased the risk of immediate postoperative new motor deficits (P = 0.0216). CONCLUSIONS This study shows that probabilities of immediate postoperative new motor deficits increase with the severity of intraoperative MEP changes. In addition, our results support the value of surgical interventions triggered by MEP deteriorations to reduce postoperative adverse motor outcomes.