title: Single Pulse Electrical Stimulation to identify epileptogenic cortex: Clinical information obtained from early evoked responses.
abstract: OBJECTIVE
  Single Pulse Electrical Stimulation (SPES) probes epileptogenic cortex during electrocorticography. Two SPES responses are described: pathological delayed responses (DR, >100 ms) associated with the seizure onset zone (SOZ) and physiological early responses (ER, <100 ms) that map cortical connectivity. We analyzed properties of ERs, including frequencies >80 Hz, in the SOZ and seizure propagation areas.
  
  
  METHODS
  We used data from 12 refractory epilepsy patients. SPES consisted of 10 pulses of 1 ms, 4-8 mA and 5s interval on adjacent electrodes pairs. Data were available at 2048 samples/s for six and 512 samples/s (22 bits) for eight patients and analyzed in the time-frequency (TF) and time-domain (TD).
  
  
  RESULTS
  Electrodes with ERs were stronger associated with SOZ than non-SOZ electrodes. ERs with frequency content >80 Hz exist and are specific for SOZ channels. ERs evoked by stimulation of seizure onset electrodes were associated with electrodes involved in seizure propagation.
  
  
  CONCLUSIONS
  Analysis of ERs can reveal aspects of pathology, manifested by association with seizure propagation and areas with high ER numbers that coincide with the SOZ.
  
  
  CONCLUSIONS
  Not only DRs, but also ERs could have clinical value for mapping epileptogenic cortex and help to unravel aspects of the epileptic network.
authors.affiliation: Brain Center Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Center Utrecht, Utrecht, The Netherlands; MIRA, Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.
authors.forename: B E
authors.initials: BE
authors.lastname: Mouthaan
authors.affiliation: Brain Center Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Center Utrecht, Utrecht, The Netherlands. Electronic address: m.a.vanhetklooster-2@umcutrecht.nl.
authors.forename: M A
authors.initials: MA
authors.lastname: van 't Klooster
authors.affiliation: Brain Center Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Center Utrecht, Utrecht, The Netherlands; MIRA, Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Keizer
authors.affiliation: Brain Center Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Center Utrecht, Utrecht, The Netherlands; MIRA, Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.
authors.forename: G J
authors.initials: GJ
authors.lastname: Hebbink
authors.affiliation: Brain Center Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: F S S
authors.initials: FSS
authors.lastname: Leijten
authors.affiliation: Brain Center Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: C H
authors.initials: CH
authors.lastname: Ferrier
authors.affiliation: MIRA, Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.
authors.forename: M J A M
authors.initials: MJAM
authors.lastname: van Putten
authors.affiliation: Brain Center Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Center Utrecht, Utrecht, The Netherlands; SEIN - Stichting Epilepsie Instellingen Nederland, Heemstede, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Zijlmans
authors.affiliation: Brain Center Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: G J M
authors.initials: GJM
authors.lastname: Huiskamp
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000503:physiopathology*; D002648:Child; D004558:Electric Stimulation / Q000379:methods; D000069280:Electrocorticography / Q000379:methods*; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods; D004827:Epilepsy / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D055815:Young Adult
keywords: Electrical stimulation; Epilepsy surgery; Evoked potentials; High frequency oscillations; Intracranial electrodes