Univeristy Medical Center Groningen - Department of Neurosurgery, Univeristy Medical Center Groningen - Department of Anesthesiology, University Medical Center Groningen - Department of Neurology,

OBJECTIVE: The influence of anesthetic depth on Tc-mMEP (transcranial electrical stimulation muscle motor-evoked-potential) characteristics is not known. Anesthetic depth is commonly quantified with the bispectral-index (BIS). The association of stepwise changes in BIS on Tc-mMEP characteristics in an adolescent patient is described. METHODS: A female with idiopathic scoliosis was included in an ongoing prospective observational study examining the effects of depth of anesthesia on Tc-mMEPs. Preoperative neurological examination showed no abnormalities.