title: Presurgical language mapping in children with epilepsy: clinical usefulness of functional magnetic resonance imaging for the planning of cortical stimulation.
abstract: OBJECTIVE
  Presurgical language mapping in dominant hemisphere epilepsy to evaluate the risk of postoperative deficit is particularly difficult in children. Extraoperative invasive cortical stimulation can show some areas critical to language, but not all of them, due to scarce sampling, poor cooperation, cortical immaturity, or network reorganization, whereas functional magnetic resonance imaging (fMRI) displays entire networks involved in, but not necessarily critical to, language. In a homogeneous series of children with epilepsy, we compared the contributions of language fMRI and depth electrode stimulations to optimize language mapping.
  
  
  METHODS
  Eight children (7.5-15.5 years) with left frontal or temporal epilepsy underwent language fMRI and language stimulation with depth electrodes as part of their comprehensive presurgical workup. fMRI data collected during sentence generation were analyzed using statistical parametric mapping (SPM2) (false discovery rate [FDR] p < 0.05). Bipolar stimulations were performed during language production tasks. By coregistering fMRI and postimplantation computed tomography (CT) images, we were able to directly compare the cortical areas identified by both investigations.
  
  
  RESULTS
  fMRI during sentence generation robustly showed activation in the whole perisylvian regions with little reorganization (left hemisphere dominant in 7). Of the 184 electrode contacts tested for language, only 8 were positive (language disruption) in three of the seven patients with periictal language impairment and left language dominance. All of the positive contacts colocalized with an fMRI activated cluster, that is, fMRI did not miss any region critical to language (sensitivity = 100%). However, 54 of the 176 negative contacts were within activated clusters (low specificity).
  
  
  CONCLUSIONS
  In children with epilepsy, the sensitivity of fMRI during sentence generation allows for the detection of all critical regions displayed by cortical stimulation within the large perisylvian language network, but with a low specificity. It is, therefore, useful to optimize the placement of intracranial electrodes when language mapping is necessary. Systematic planning of the electrode placement according to language fMRI maps should increase the yield of extraoperative cortical stimulation, which appears rather low in children when compared to adults.
authors: Pediatric Neurosurgery Unit, Fondation Ophtalmologique A de Rothschild, Paris, France.
authors: Sandrine
authors: S
authors: de Ribaupierre
authors: Martine
authors: M
authors: Fohlen
authors: Christine
authors: C
authors: Bulteau
authors: Georg
authors: G
authors: Dorfmüller
authors: Olivier
authors: O
authors: Delalande
authors: Olivier
authors: O
authors: Dulac
authors: Catherine
authors: C
authors: Chiron
authors: Lucie
authors: L
authors: Hertz-Pannier
mesh_terms: D000293:Adolescent; D001931:Brain Mapping / Q000379:methods; D002648:Child; D004558:Electric Stimulation / Q000379:methods; D004827:Epilepsy / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D007839:Functional Laterality; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D057234:Preoperative Period; D013702:Temporal Lobe / Q000503:physiopathology*