title: Sleep influences the intracerebral EEG pattern of focal cortical dysplasia.
abstract: OBJECTIVE
  Focal cortical dysplasia (FCD) is able to generate an intrinsic pathological EEG activity characterized by a continuous or near-continuous spiking. Different patterns of discharge were described. We examined quantitatively the distribution of the intracerebral FCD patterns in relation to sleep in order to investigate whether this activity is independent of thalamocortical influences.
  
  
  METHODS
  We analyzed the first sleep cycle of 5 patients with a diagnosis of FCD type II who underwent combined scalp-intracranial electroencephalography (EEG), and showed an intracranial EEG pattern typical for FCD. Three patterns of FCD intracranial EEG activity were identified in all 5 patients, and visually marked for a maximum of 30min of each stage (wake, N1, N2, N3, REM): spike or polyspike exceeding 2Hz (pattern 1), spike or polyspike interrupted by flat periods below 2Hz (pattern 2) and discharges of >15Hz low-voltage rhythmic activity with regular morphology (pattern 3). After marking, the percentages of the three patterns across the different stages were calculated.
  
  
  RESULTS
  The three patterns of FCD were present between 45% and 97% of the total time analyzed. Pattern 1 was the predominant pattern in wakefulness (73-100%), N1 (76-97%) and N2 (58-88.5%) in all patients, and in REM in 4 of 5 patients (91-100%). During N2 and N3, there was an increase in pattern 2 in all patients, becoming the predominant pattern in 3 of the 5 patients during N3 (63-89%). Pattern 3 was rare and only sporadically observed during N2 and N3. Wakefulness and REM sleep showed a similar pattern (pattern 1) with a slight amplitude reduction in REM sleep.
  
  
  CONCLUSIONS
  Despite the presence of an almost continuous discharge, sleep is an important modulator of the pathological EEG patterns found in FCD type II. This might suggest that dysplastic tissue is influenced by the thalamo-cortical control mechanisms involved in the generation of sleep.
authors.affiliation: Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, Québec H3A 2B4, Canada; Neurology Department, Centro Hospitalar do Algarve, Faro Hospital, Rua Leao Penedo, 8000-386 Faro, Portugal. Electronic address: ines.mcordeiro@gmail.com.
authors.forename: Inês
authors.initials: I
authors.lastname: Menezes Cordeiro
authors.affiliation: Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, Québec H3A 2B4, Canada. Electronic address: nellen@ieee.org.
authors.forename: Nicolas
authors.initials: N
authors.lastname: von Ellenrieder
authors.affiliation: Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, Québec H3A 2B4, Canada. Electronic address: natalja.zazubovits@mcgill.ca.
authors.forename: Natalja
authors.initials: N
authors.lastname: Zazubovits
authors.affiliation: Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, Québec H3A 2B4, Canada. Electronic address: francois.dubeau@mcgill.ca.
authors.forename: François
authors.initials: F
authors.lastname: Dubeau
authors.affiliation: Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, Québec H3A 2B4, Canada. Electronic address: jean.gotman@mcgill.ca.
authors.forename: Jean
authors.initials: J
authors.lastname: Gotman
authors.affiliation: Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, Québec H3A 2B4, Canada; Neurology Department, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria. Electronic address: birgit.frauscher@mcgill.ca.
authors.forename: Birgit
authors.initials: B
authors.lastname: Frauscher
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D058256:Brain Waves / Q000502:physiology*; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D065703:Malformations of Cortical Development, Group I / Q000503:physiopathology*; D017286:Polysomnography; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages; D055815:Young Adult
keywords: AASM; Epilepsy; Interictal; Intracerebral EEG; Polysomnography; Thalamo-cortical