title: Utility of foramen ovale electrodes in mesial temporal lobe epilepsy.
abstract: OBJECTIVE
  To determine the ability of foramen ovale electrodes (FOEs) to localize epileptogenic foci after inconclusive noninvasive investigations in patients with suspected mesial temporal lobe epilepsy (MTLE).
  
  
  METHODS
  We identified patients with medically intractable epilepsy who had undergone FOE investigation for initial invasive monitoring at our institution between 2005 and 2012. Indications for initiating FOE investigation were grouped into four categories: (1) bilateral anterior temporal ictal activity on scalp electroencephalography (EEG), (2) unclear laterality of scalp EEG onset due to muscle artifact or significant delay following clinical manifestation, (3) discordance between ictal and interictal discharges, and (4) investigation of a specific anatomic abnormality or competing putative focus. The FOE investigation was classified as informative if it provided sufficient evidence to make a treatment decision.
  
  
  RESULTS
  Forty-two consecutive patients underwent FOE investigation, which was informative in 38 patients (90.5%). Of these 38 patients, 24 were determined to be appropriate candidates for resective surgery. Five were localized sufficiently for surgery, but were considered high risk for verbal memory deficit, and nine were deemed poor surgical candidates because of bilateral ictal origins. The remaining 4 of 42 patients had inconclusive FOE studies and were referred for further invasive investigation. Of the 18 patients who underwent resective surgery, 13 (72%) were seizure-free (Engel class I) at last follow-up (mean 22.5 months).
  
  
  CONCLUSIONS
  More than 90% of our 42 FOE studies provided sufficient evidence to render treatment decisions. When undertaken with an appropriate hypothesis, FOE investigations are a minimally invasive and efficacious means for evaluating patients with suspected MTLE after an inconclusive noninvasive investigation.
authors.affiliation: Department of Neurosurgery, Columbia University Medical Center, New York Presbyterian Hospital, New York, New York, U.S.A.
authors.forename: Sameer A
authors.initials: SA
authors.lastname: Sheth
authors.affiliation: Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, U.S.A.
authors.forename: Joshua P
authors.identifier: http://orcid.org/0000-0001-5300-0010
authors.initials: JP
authors.lastname: Aronson
authors.affiliation: Division of Epilepsy, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, U.S.A.
authors.forename: Mouhsin M
authors.initials: MM
authors.lastname: Shafi
authors.affiliation: Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, U.S.A.
authors.forename: H Westley
authors.initials: HW
authors.lastname: Phillips
authors.affiliation: Department of Neurology, Emory University School of Medicine, Atlanta, Georgia, U.S.A.
authors.forename: Naymee
authors.initials: N
authors.lastname: Velez-Ruiz
authors.affiliation: Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, U.S.A.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Walcott
authors.affiliation: Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, U.S.A.
authors.forename: Churl-Su
authors.initials: CS
authors.lastname: Kwon
authors.affiliation: Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, U.S.A.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Mian
authors.affiliation: Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, U.S.A.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Dykstra
authors.affiliation: Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, U.S.A.
authors.forename: Andrew
authors.identifier: http://orcid.org/0000-0002-0828-826X
authors.initials: A
authors.lastname: Cole
authors.affiliation: Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, U.S.A.
authors.forename: Emad N
authors.initials: EN
authors.lastname: Eskandar
mesh_terms: D000293:Adolescent; D000328:Adult; D004292:Dominance, Cerebral / Q000502:physiology; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods*; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D054085:Foramen Ovale / Q000503:physiopathology*; D006801:Humans; D008297:Male; D011939:Mental Recall / Q000502:physiology; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012815:Signal Processing, Computer-Assisted; D014706:Verbal Learning / Q000502:physiology
keywords: Depth electrodes; Epilepsy; Foramen ovale; Mesial temporal sclerosis