title: Language lateralization by fMRI and Wada testing in 229 patients with epilepsy: rates and predictors of discordance.
abstract: OBJECTIVE
  To more definitively characterize Wada/functional magnetic resonance imaging (fMRI) language dominance discordance rates with the largest sample of patients with epilepsy to date, and to examine demographic, clinical, and methodologic predictors of discordance.
  
  
  METHODS
  Two hundred twenty-nine patients with epilepsy underwent both a standardized Wada test and a semantic decision fMRI language protocol in a prospective research study. Language laterality indices were computed for each test using automated and double-blind methods, and Wada/fMRI discordance rates were calculated using objective criteria for discordance. Regression analyses were used to explore a range of variables that might predict discordance, including subject variables, Wada quality indices, and fMRI quality indices.
  
  
  RESULTS
  Discordant results were observed in 14% of patients. Discordance was highest among those categorized by either test as having bilateral language. In a multivariate model, the only factor that predicted discordance was the degree of atypical language dominance on fMRI.
  
  
  CONCLUSIONS
  fMRI language lateralization is generally concordant with Wada testing. The degree of rightward shift of language dominance on fMRI testing is strongly correlated with Wada/fMRI discordance, suggesting that fMRI may be more sensitive than Wada to right hemisphere language processing, although the clinical significance of this increased sensitivity is unknown. The relative accuracy of fMRI versus Wada testing for predicting postsurgical language outcome in discordant cases remains a topic for future research.
authors.affiliation: Department of Neurology and the Comprehensive Epilepsy Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. jjanecek@mcw.edu
authors.forename: Julie K
authors.initials: JK
authors.lastname: Janecek
authors.forename: Sara J
authors.initials: SJ
authors.lastname: Swanson
authors.forename: David S
authors.initials: DS
authors.lastname: Sabsevitz
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Hammeke
authors.forename: Manoj
authors.initials: M
authors.lastname: Raghavan
authors.forename: Megan
authors.initials: M
authors.lastname: E Rozman
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Binder
mesh_terms: D000328:Adult; D017668:Age of Onset; D000654:Amobarbital; D004569:Electroencephalography; D004827:Epilepsy / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D006993:Hypnotics and Sedatives; D007091:Image Processing, Computer-Assisted; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies
chemical_list: D006993:Hypnotics and Sedatives; D000654:Amobarbital