title: Cerebral lesions can impair fMRI-based language lateralization.
abstract: OBJECTIVE
  Several small patient studies and case reports raise concerns that the reliability of functional magnetic resonance imaging (fMRI) may be impaired in the vicinity of cerebral lesions. This could affect the clinical validity of fMRI for presurgical language lateralization. The current study sets out to identify if a systematic effect of lesion type and localization on fMRI exists.
  
  
  METHODS
  We classify lesions typically occurring in epilepsy patients according to (1) their potential to disturb blood oxygenation level dependent (BOLD)-effect generation or detection or to disturb spatial brain normalization, and (2) the proximity of lesions to protocol-specific volumes of interest (VOIs). The effect of lesions is evaluated through the examination of 238 epilepsy patients and a subgroup of 37 patients with suspected unilateral left-language dominance according to the Wada test.
  
  
  RESULTS
  Patients with fMRI-critical lesions such as cavernomas, gliomas, and mass defects close to VOIs, or with severe atrophy, show lower lateralization indices (LIs) and more often discordant language lateralization with the Wada test than do patients without such lesions.
  
  
  CONCLUSIONS
  This study points seriously toward fMRI-language lateralization being sensitive to cerebral lesions. Some lesion types and locations are more critical than others. Our results question the noncritical application of fMRI in patients with cerebral lesions.
authors.affiliation: Department of Epileptology, University Hospital Bonn, Bonn, Germany. j.wellmer@gmx.de
authors.forename: Jörg
authors.initials: J
authors.lastname: Wellmer
authors.forename: Bernd
authors.initials: B
authors.lastname: Weber
authors.forename: Horst
authors.initials: H
authors.lastname: Urbach
authors.forename: Jürgen
authors.initials: J
authors.lastname: Reul
authors.forename: Guillen
authors.initials: G
authors.lastname: Fernandez
authors.forename: Christian E
authors.initials: CE
authors.lastname: Elger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000654:Amobarbital / Q000008:administration & dosage; D001927:Brain Diseases / Q000175:diagnosis / Q000503:physiopathology*; D001931:Brain Mapping; D001932:Brain Neoplasms / Q000175:diagnosis / Q000503:physiopathology; D002648:Child; D004569:Electroencephalography; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007802:Language; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011597:Psychomotor Performance; D015203:Reproducibility of Results; D012660:Semantics
chemical_list: D000654:Amobarbital; D010100:Oxygen