title: High frequency oscillations mirror disease activity in patients with focal cortical dysplasia.
abstract: OBJECTIVE
  The study analyzes the occurrence of high frequency oscillations in different types of focal cortical dysplasia in 22 patients with refractory epilepsy. High frequency oscillations are biomarkers for epileptic tissue, but it is unknown whether they can reflect increasingly dysplastic tissue changes as well as epileptic disease activity.
  
  
  METHODS
  High frequency oscillations (80-450 Hz) were visually marked by two independent reviewers in all channels of intracranial implanted grid, strips, and depth electrodes in patients with focal cortical dysplasia and refractory epilepsy. Rates of high frequency oscillations in patients with pathologically confirmed focal cortical dysplasia of Palmini type 1a and b were compared with those in type 2a and b.
  
  
  RESULTS
  Patients with focal cortical dysplasia type 2 had significantly more seizures than those with type 1 (p < 0.001). Rates of high frequency oscillations were significantly higher in patients with focal cortical dysplasia type 2 versus type 1 (p < 0.001). In addition, it could be confirmed that rates of high frequency oscillations were significantly higher in presumed epileptogenic areas than outside (p < 0.001).
  
  
  CONCLUSIONS
  Activity of high frequency oscillations mirrors the higher epileptogenicity of focal cortical dysplasia type 2 lesions compared to type 1 lesions. Therefore, rates of high frequency oscillations can reflect disease activity of a lesion. This has implications for the use of high frequency oscillations as biomarkers for epileptogenic areas, because a detailed analysis of their rates may be necessary to use high frequency oscillations as a predictive tool in epilepsy surgery.
authors.affiliation: Department of Neuropediatrics and Muscular Diseases, University of Freiburg, Freiburg, Germany.
authors.forename: Karolin
authors.initials: K
authors.lastname: Kerber
authors.forename: Pierre
authors.initials: P
authors.lastname: LeVan
authors.forename: Matthias
authors.initials: M
authors.lastname: Dümpelmann
authors.forename: Susanne
authors.initials: S
authors.lastname: Fauser
authors.forename: Rudolf
authors.initials: R
authors.lastname: Korinthenberg
authors.forename: Andreas
authors.initials: A
authors.lastname: Schulze-Bonhage
authors.forename: Julia
authors.initials: J
authors.lastname: Jacobs
mesh_terms: D000293:Adolescent; D000328:Adult; D001927:Brain Diseases / Q000145:classification / Q000503:physiopathology* / Q000601:surgery; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology*; D002648:Child; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004576:Electromyography; D004827:Epilepsy / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D054220:Malformations of Cortical Development / Q000145:classification / Q000503:physiopathology* / Q000601:surgery; D065703:Malformations of Cortical Development, Group I; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D012815:Signal Processing, Computer-Assisted; D013223:Statistics as Topic; D055815:Young Adult
keywords: Cortical dysplasia; EEG; Epilepsy surgery; Epileptogenesis; High frequency oscillations; Intracranial electrodes