Are There False-Negative and False-Positive Motor-Evoked Potentials?

ABSTRACTS OF REVIEWED ARTICLESFalse-Negative Transcranial Motor-Evoked Potentials During Scoliosis Surgery Causing ParalysisA Case Report With Literature ReviewModi HN, Suh S-W, Yang J-H, Yoon J-YSpine 2009;34:E896–E900Study DesignCase report.ObjectiveTo report a case of false-negative intraoperative motor-evoked potentials (MEP) that developed paraplegia after surgery.Summary of Background DataAlthough several false-negative results have been reported with somatosensory-evoked potentials, there is no report noted with MEP. Therefore, several authors have preferred using MEPs as a gold standard in neuromonitoring.MethodsWe report a case of false-negative MEP during the scoliosis surgery which is the first report showing false-negative MEPs during operation.ResultsA 15-year-old girl with severe kyphoscoliosis (Cobb angle, 140°) in neurofibromatosis was operated for correction and posterior spinal fusion surgery, using pedicle screw instrumentation. Intraoperative neuromonitoring did not show any change in MEPs throughout the procedure, however, she woke-up with paraplegia. Immediate implant release could not recover her neurology functionally at last follow-up. Positive event during the operation was massive blood loss which could not show drop in MEPs as an ischemic cord injury (probable cause). Postoperative CT scan in both patients did not show any injury with pedicle screw as implants were well placed within the pedicles. Reviewing the literature, we could not find out any prospective study in animals identifying false-negative results with MEPs.ConclusionFrom our experience of false-negative MEPs, we conclude that unwanted events with use of MEP in scoliosis or other spinal surgeries. We propose further prospective research on animals to solve this issue.False Negative and Positive Motor Evoked Potentials in One PatientIs Single Motor Evoked Potential Monitoring Reliable Method?A Case Report and Literature ReviewHong J-H, Suh S-W, Modi HN, Hur C-Y, Song H-R, Park JHSpine 2010;35:E912–E916Study DesignA case report and literature review.ObjectiveTo report a false negative and delayed positive motor-evoked potential (MEP) in 1 patient.Summary of Background DataAn unreliable MEP can result in fatal outcomes because surgeons have recently begun to depend on the MEP for intraoperative decision-making.MethodsWe report a case of a false MEP during scoliosis surgery that showed false negative and positive MEPs during a series of operations.ResultsA 23-year-old