title: A retrospective analysis of the effect of general anesthetics on the successful detection of interictal epileptiform activity in magnetoencephalography.
abstract: BACKGROUND
  A magnetoencephalography (MEG) study requires the patient to lie still for a prolonged period of time. In children and uncooperative adults with epilepsy, general anesthesia or sedation may be required to insure a good quality study. As general anesthetics have anticonvulsant and proconvulsant properties, we investigated whether the use of anesthesia reduced the successful detection of interictal epilepsy activity.
  
  
  METHODS
  MEG testing was performed on 41 epilepsy patients (10 women, 31 men; 1-48 yr) while anesthetized. To determine the impact of anesthesia on the identification of epileptiform activity, the anesthesia group of patients was compared with all other patients with epilepsy who were recorded in our laboratory without anesthesia, as well as with a subgroup of children with epilepsy who were able to be recorded without the need for anesthesia.
  
  
  RESULTS
  Propofol was used in 38 patients, etomidate in two, and one received sevoflurane. Twenty-nine (71%) were found to have interictal epileptiform activity in their MEG results. The percentage of MEG studies with a positive yield for interictal epileptiform activity is comparable with the percentage (63%) found in the patients with epilepsy undergoing MEG without anesthesia. In the 38 children younger than 18 yr, 28 (74%) had interictal epileptiform activity compared with 80% done without anesthesia.
  
  
  CONCLUSIONS
  We conclude that levels of anesthesia needed to provide unconsciousness and immobility during MEG studies do not significantly alter the likelihood of recording interictal epileptiform spike activity with MEG.
authors.affiliation: Department of Anesthesiology, Henry Ford Medical Group, Detroit, Michigan, USA.
authors.forename: Guruswamy
authors.initials: G
authors.lastname: Balakrishnan
authors.forename: Kavita M
authors.initials: KM
authors.lastname: Grover
authors.forename: Karen
authors.initials: K
authors.lastname: Mason
authors.forename: Brien
authors.initials: B
authors.lastname: Smith
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Barkley
authors.forename: Norman
authors.initials: N
authors.lastname: Tepley
authors.forename: Susan M
authors.initials: SM
authors.lastname: Bowyer
mesh_terms: D000293:Adolescent; D000328:Adult; D018681:Anesthetics, General / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D004827:Epilepsy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007223:Infant; D015225:Magnetoencephalography / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D018681:Anesthetics, General