title: Effect of partial drug withdrawal on the lateralization of interictal epileptiform discharges and its relationship to surgical outcome in patients with hippocampal sclerosis.
abstract: OBJECTIVE
  To assess changes in the relative lateralization of interictal epileptiform discharges (IEDs) and interictal EEG prognostic value in terms of surgical outcome between periods with full medication (FMP) and reduced medication (RMP) in patients with temporal lobe epilepsy (TLE) associated with hippocampal sclerosis (HS).
  
  
  METHODS
  Interictal scalp EEGs of 43 patients were evaluated for the presence of IEDs separately in a waking state (WS) and sleeping state (SS) during FMP and RMP. In each period, patients were categorized as having unitemporal or bitemporal IEDs. Surgical outcome was classified at year 1 after surgery and at last follow-up visit as Engel I or Engel II-IV; and alternatively as completely seizure-free or not seizure-free.
  
  
  RESULTS
  There were significant changes in relative IED lateralization between FMP and RMP during SS. The representation of patients with unitemporal IEDs declined from 37 (86%) in FMP during SS to 25 (58%) in RMP during SS (p=0.003). At year 1 after surgery, the relative IED lateralization is a predictive factor for surgical outcome defined as Engel I vs. Engel II-IV in both FMP during WS (p=0.037) and during SS (p=0.007), and for surgical outcome defined as completely seizure-free vs. not seizure-free in FMP during SS (p=0.042). At last follow up visit, the relative IED lateralization is a predictor for outcome defined as Engel I vs. Engel II-IV in FMP during SS (p=0.020), and for outcome defined as completely seizure-free vs. not seizure-free in both FMP during WS (p=0.043) and in FMP during SS (p=0.015). When stepwise logistic regression analysis was applied, only FMP during SS was found to be an independent predictor for surgical outcome at year 1 after surgery (completely seizure-free vs. not seizure-free p=0.032, Engel I vs. Engel II-IV p=0.006) and at last follow-up visit (completely seizure-free vs. not seizure-free p=0.024, Engel I vs. Engel II-IV p=0.017). Gender was found to be independent predictor for surgical efficacy at year 1 if the outcome was defined as completely seizure-free vs. not seizure-free (p=0.036).
  
  
  CONCLUSIONS
  The predictive value of relative IED lateralization with respect to surgical outcome in interictal EEG is present only during FMP; the predictive value decreases with the reduction of AEDs caused by the change of relative IED lateralization.
authors: Brno Epilepsy Center, First Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic; Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic. Electronic address: irena.dolezalova@fnusa.cz.
authors: Irena
authors: I
authors: Doležalová
authors: Brno Epilepsy Center, First Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic; Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic.
authors: Milan
authors: M
authors: Brázdil
authors: First Department of Pathological Anatomy, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors: Markéta
authors: M
authors: Hermanová
authors: Institute of Biostatistics and Analyses, Masaryk University, Brno, Czech Republic.
authors: Eva
authors: E
authors: Janoušová
authors: Brno Epilepsy Center, First Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic; Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic.
authors: Robert
authors: R
authors: Kuba
mesh_terms: D000328:Adult; D000927:Anticonvulsants / Q000008:administration & dosage* / Q000009:adverse effects; D004569:Electroencephalography / Q000379:methods*; D004833:Epilepsy, Temporal Lobe / Q000188:drug therapy* / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006624:Hippocampus / Q000473:pathology* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012598:Sclerosis / Q000188:drug therapy / Q000503:physiopathology / Q000601:surgery; D013375:Substance Withdrawal Syndrome / Q000175:diagnosis / Q000503:physiopathology*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000927:Anticonvulsants
keywords: Bitemporal IEDs; Epilepsy; Hippocampal sclerosis; Interictal epileptiform discharges (IEDs); Outcome; Unitemporal IEDs