title: Electrocorticographic language mapping in children by high-gamma synchronization during spontaneous conversation: comparison with conventional electrical cortical stimulation.
abstract: BACKGROUND
  This study describes development of a novel language mapping approach using high-γ modulation in electrocorticograph (ECoG) during spontaneous conversation, and its comparison with electrical cortical stimulation (ECS) in childhood-onset drug-resistant epilepsy.
  
  
  METHODS
  Patients undergoing invasive pre-surgical monitoring and able to converse with the investigator were eligible. ECoG signals and synchronized audio were acquired during quiet baseline and during natural conversation between investigator and the patient. Using Signal Modeling for Real-time Identification and Event Detection (SIGFRIED) procedure, a statistical model for baseline high-γ (70-116 Hz) power, and a single score for each channel representing the probability that the power features in the experimental signal window belonged to the baseline model, were calculated. Electrodes with significant high-γ responses (HGS) were plotted on the 3D cortical model. Sensitivity, specificity, positive and negative predictive values (PPV, NPV), and classification accuracy were calculated compared to ECS.
  
  
  RESULTS
  Seven patients were included (4 males, mean age 10.28 ± 4.07 years). Significant high-γ responses were observed in classic language areas in the left hemisphere plus in some homologous right hemispheric areas. Compared with clinical standard ECS mapping, the sensitivity and specificity of HGS mapping was 88.89% and 63.64%, respectively, and PPV and NPV were 35.29% and 96.25%, with an overall accuracy of 68.24%. HGS mapping was able to correctly determine all ECS+ sites in 6 of 7 patients and all false-sites (ECS+, HGS- for visual naming, n = 3) were attributable to only 1 patient.
  
  
  CONCLUSIONS
  This study supports the feasibility of language mapping with ECoG HGS during spontaneous conversation, and its accuracy compared to traditional ECS. Given long-standing concerns about ecological validity of ECS mapping of cued language tasks, and difficulties encountered with its use in children, ECoG mapping of spontaneous language may provide a valid alternative for clinical use.
authors.affiliation: Comprehensive Epilepsy Center, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA. Electronic address: Ravindra.Arya@cchmc.org.
authors.forename: Ravindra
authors.initials: R
authors.lastname: Arya
authors.affiliation: Comprehensive Epilepsy Center, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Pediatric Neuroimaging Research Consortium, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: J Adam
authors.initials: JA
authors.lastname: Wilson
authors.affiliation: Comprehensive Epilepsy Center, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Pediatric Neuroimaging Research Consortium, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Vannest
authors.affiliation: Comprehensive Epilepsy Center, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Anna W
authors.initials: AW
authors.lastname: Byars
authors.affiliation: Comprehensive Epilepsy Center, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Hansel M
authors.initials: HM
authors.lastname: Greiner
authors.affiliation: Comprehensive Epilepsy Center, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Division of Clinical Engineering, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Buroker
authors.affiliation: Comprehensive Epilepsy Center, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Hisako
authors.initials: H
authors.lastname: Fujiwara
authors.affiliation: Division of Pediatric Neurosurgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Francesco T
authors.initials: FT
authors.lastname: Mangano
authors.affiliation: Comprehensive Epilepsy Center, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Katherine D
authors.initials: KD
authors.lastname: Holland
authors.affiliation: Comprehensive Epilepsy Center, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Division of Epidemiology and Biostatistics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Horn
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Nathan E
authors.initials: NE
authors.lastname: Crone
authors.affiliation: Comprehensive Epilepsy Center, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Douglas F
authors.initials: DF
authors.lastname: Rose
mesh_terms: D000293:Adolescent; D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D004558:Electric Stimulation / Q000379:methods*; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000503:physiopathology; D005240:Feasibility Studies; D005260:Female; D065818:Gamma Rhythm; D006801:Humans; D007398:Interpersonal Relations; D007802:Language; D008297:Male; D008959:Models, Neurological; D011300:Preoperative Care; D012680:Sensitivity and Specificity; D013060:Speech / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology
keywords: Drug resistant epilepsy; Electrical cortical stimulation; Electrocorticograph; High-γ synchronization; Language mapping