title: Atypical cortical language organization in epilepsy patients: evidence for divergent hemispheric dominance for receptive and expressive language function.
abstract: The central goal of presurgical language mapping is to identify brain regions that subserve cortical language function to minimize postsurgical language deficits. Presurgical language mapping in patients with epilepsy presents a key challenge because of the atypical pattern of hemispheric language dominance found in this population, with higher incidences of bilateral and right-biased language dominance than typical. In this prospective study, we combine magnetoencephalography with a panel of tasks designed to separately assess receptive and expressive function to provide a sensitive measure of language function in 15 candidates for resective surgery. We report the following: 4 of 15 patients (27%) showed left hemisphere dominance across all tasks, 4 of 15 patients (27%) showed right hemisphere dominance across all tasks, and 7 of 15 (46%) showed discordant language dominance, with right-dominant receptive and left-dominant expressive language. All patients with discordant language dominance showed this right-receptive and left-expressive pattern. Results provide further evidence supporting the importance of using a panel of tasks to assess separable aspects of language function. The clinical relevance of the findings is discussed, especially about current clinical operative measures for assessing language dominance, which use single hemisphere procedure (intracarotid amobarbital procedure and awake intraoperative stimulation) for determining language laterality.
authors.affiliation: *Department of Neurology, David Geffen School of Medicine, The University of California, Los Angeles, California, U.S.A.; †MEG Laboratory, Scripps Green Hospital, La Jolla, California, U.S.A.; ‡Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, California, U.S.A.; §Division of Neurology, Scripps Clinic, La Jolla, California, U.S.A.; and ‖Department of Cognitive Sciences, University of California, Irvine, California, U.S.A.
authors.forename: Dawn S
authors.initials: DS
authors.lastname: Eliashiv
authors.forename: Lacey
authors.initials: L
authors.lastname: Kurelowech
authors.forename: Patti
authors.initials: P
authors.lastname: Quint
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Chung
authors.forename: Shirley M
authors.initials: SM
authors.lastname: Otis
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Gage
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007802:Language; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation / Q000379:methods; D011446:Prospective Studies; D055815:Young Adult