title: The effect of age on motor evoked potentials in children under propofol/isoflurane anesthesia.
abstract: Intraoperative transcranial motor evoked potential (MEP) monitoring may help prevent neurologic injury during spine surgery. This type of monitoring may be difficult in the pediatric population under general anesthesia. We retrospectively reviewed data from 56 children, aged 2 to 18 yr, who were to undergo surgical correction of idiopathic scoliosis with MEP monitoring. Under combined isoflurane-propofol general anesthesia, before incision, we examined the minimum stimulating threshold voltage required to achieve a 50-microvolt or greater MEP response amplitude. Younger age was associated with an increase in the threshold voltage needed to elicit a sufficient MEP response. In addition, younger age was associated with longer stimulating pulse trains and greater need to adjust stimulating scalp electrodes. Body surface area, height, weight, and body mass index were also significant factors, but they were not independent predictors, after adjusting for age. Younger children received significantly lower levels of isoflurane and comparable doses of propofol, compared with older patients. Stronger stimulation needed to produce MEP responses in younger patients may reflect immaturity of their central nervous system, specifically conduction by the descending corticospinal motor tracts. Greater attention must be given to optimizing physiologic variables, limiting depressant anesthetics, and selecting the most favorable stimulating conditions in children, especially those <10 yr old.
authors.affiliation: Department of Anesthesia & Perioperative Care, Box 0648, Room L-008, University of California, San Francisco, San Francisco, California 94143-0648, USA. lieberman@anesthesia.ucsf.edu
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Lieberman
authors.forename: Russ
authors.initials: R
authors.lastname: Lyon
authors.forename: John
authors.initials: J
authors.lastname: Feiner
authors.forename: Mohammad
authors.initials: M
authors.lastname: Diab
authors.forename: George A
authors.initials: GA
authors.lastname: Gregory
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000758:Anesthesia; D002648:Child; D002675:Child, Preschool; D019054:Evoked Potentials, Motor / Q000187:drug effects*; D005260:Female; D006801:Humans; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D016343:Monitoring, Intraoperative; D015999:Multivariate Analysis; D015742:Propofol / Q000494:pharmacology*; D012189:Retrospective Studies
chemical_list: D007530:Isoflurane; D015742:Propofol