title: The effect of seizure focus on regional language processing areas.
abstract: OBJECTIVE
  To determine the effect of seizure focus location within the left hemisphere on the expression of regional language dominance.
  
  
  METHODS
  In this cross-sectional study we investigated 90 patients (mean age 23.3 ± 12.9 years) with left hemisphere focal epilepsy (mean age onset 11.7 ± 8.3 years). Eighteen patients had a frontal lobe focus and 72 had a temporal lobe focus (43 mesial; 29 neocortical). Subjects performed an auditory word definition language paradigm using 3 Tesla blood oxygen level dependent (BOLD) EPI functional magnetic resonance imaging (fMRI). Data were analyzed in SPM2. Regional laterality indices (LIs) for inferior frontal gyrus (IFG), and Wernicke's area (WA), were calculated using a bootstrap method. Categorical language dominance and mean LI were analyzed.
  
  
  RESULTS
  Mean WA LI was lower for subjects with a mesial temporal focus compared with a frontal focus (p = 0.04). There was a greater proportion of atypical language in WA for subjects with a mesial temporal focus compared with a frontal focus (χ(2) = 4.37, p = 0.04). WA LI did not differ for subjects with a neocortical focus compared with a mesial focus or a frontal focus. Mean IFG LI and proportion of atypical language in IFG were similar across seizure focus groups. Age and age of onset were not correlated with mean laterality in WA or IFG. Epilepsy duration tended to be negatively correlated with WA LI (r = -0.18, p = 0.10), but not IFG LI.
  
  
  CONCLUSIONS
  Temporal lobe foci have wide-ranging effects on the distributed language system. In contrast, the effects of a frontal lobe focus appear restricted to anterior rather than posterior language processing areas.
authors.affiliation: Center for Neuroscience, Children's National Medical Center, George Washington University, Washington, District of Columbia 20010, USA.
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Duke
authors.forename: Mekdem
authors.initials: M
authors.lastname: Tesfaye
authors.forename: Madison M
authors.initials: MM
authors.lastname: Berl
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Walker
authors.forename: Eva K
authors.initials: EK
authors.lastname: Ritzl
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Fasano
authors.forename: Joan A
authors.initials: JA
authors.lastname: Conry
authors.forename: Phillip L
authors.initials: PL
authors.lastname: Pearl
authors.forename: Sususmu
authors.initials: S
authors.lastname: Sato
authors.forename: William H
authors.initials: WH
authors.lastname: Theodore
authors.forename: William D
authors.initials: WD
authors.lastname: Gaillard
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D001931:Brain Mapping; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007802:Language; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012640:Seizures / Q000473:pathology* / Q000503:physiopathology*; D055815:Young Adult