title: Somatosensory-evoked fields on magnetoencephalography for epilepsy infants younger than 4 years with total intravenous anesthesia.
abstract: OBJECTIVE
  Patients must remain immobile for magnetoencephalography (MEG) and MRI recordings to allow precise localization of brain function for pre-surgical functional mapping. In young children with epilepsy, this is accomplished with recordings during sleep or with anesthesia. This paper demonstrates that MEG can detect, characterize and localize somatosensory-evoked fields (SEF) in infants younger than 4 years of age with or without total intravenous anesthesia (TIVA).
  
  
  METHODS
  We investigated the latency, amplitude, residual error (RE) and location of the N20m of the SEF in 26 infants (mean age=2.6 years). Seventeen patients underwent TIVA and 9 patients were tested while asleep, without TIVA.
  
  
  RESULTS
  MEG detected 44 reliable SEFs (77%) in 52 median nerve stimulations. We found 27 reliable SEFs (79%) with TIVA and 13 reliable SEFs (72%) without TIVA. TIVA effects included longer latencies (p<0.001) and lower RE (p<0.05) compared to those without TIVA. Older patients and larger head circumferences also showed significantly shorter latencies (p<0.01).
  
  
  CONCLUSIONS
  TIVA resulted in reliable SEFs with lower RE and longer latencies.
  
  
  CONCLUSIONS
  MEG can detect reliable SEFs in infants younger than 4 years old. When infants require TIVA for MEG and MRI acquisition, SEFs can still be reliably observed.
authors.affiliation: Division of Neurology, Department of Pediatrics, The Hospital for Sick Children, 555 University Avenue, Toronto, Ont., Canada M5G-1X8.
authors.forename: Eduard
authors.initials: E
authors.lastname: Bercovici
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Pang
authors.forename: Rohit
authors.initials: R
authors.lastname: Sharma
authors.forename: Ismail S
authors.initials: IS
authors.lastname: Mohamed
authors.forename: Katsumi
authors.initials: K
authors.lastname: Imai
authors.forename: Ayataka
authors.initials: A
authors.lastname: Fujimoto
authors.forename: Ayako
authors.initials: A
authors.lastname: Ochi
authors.forename: Amrita
authors.initials: A
authors.lastname: Viljoen
authors.forename: Bill
authors.initials: B
authors.lastname: Chu
authors.forename: Stephanie
authors.initials: S
authors.lastname: Holowka
authors.forename: Sylvester H
authors.initials: SH
authors.lastname: Chuang
authors.forename: Sheelagh M
authors.initials: SM
authors.lastname: Kemp
authors.forename: James T
authors.initials: JT
authors.lastname: Rutka
authors.forename: O
authors.initials: O
authors.lastname: Carter Snead
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Otsubo
mesh_terms: D000704:Analysis of Variance; D000758:Anesthesia / Q000379:methods*; D000771:Anesthesia, Intravenous / Q000379:methods*; D001931:Brain Mapping; D016009:Chi-Square Distribution; D002675:Child, Preschool; D004558:Electric Stimulation / Q000379:methods; D004827:Epilepsy / Q000175:diagnosis* / Q000503:physiopathology*; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D015225:Magnetoencephalography; D008297:Male; D008475:Median Nerve / Q000503:physiopathology / Q000528:radiation effects; D011930:Reaction Time