title: Imaging language networks before and after anterior temporal lobe resection: results of a longitudinal fMRI study.
abstract: OBJECTIVE
  Anterior temporal lobe resection (ATLR) controls seizures in up to 70% of patients with intractable temporal lobe epilepsy (TLE) but, in the language dominant hemisphere, may impair language function, particularly naming. Functional reorganization can occur within the ipsilateral and contralateral hemispheres. We investigated reorganization of language in left-hemisphere-dominant patients before and after ATLR; whether preoperative functional magnetic resonance imaging (fMRI) predicts postoperative naming decline; and efficiency of postoperative language networks.
  
  
  METHODS
  We studied 44 patients with TLE due to unilateral hippocampal sclerosis (24 left) on a 3T GE-MRI scanner. All subjects performed language fMRI and neuropsychological testing preoperatively and again 4 months after left or right ATLR.
  
  
  RESULTS
  Postoperatively, individuals with left TLE had greater bilateral middle/inferior frontal fMRI activation and stronger functional connectivity from the left inferior/middle frontal gyri to the contralateral frontal lobe than preoperatively, and this was not observed in individuals with right TLE. Preoperatively, in left and right TLE, better naming correlated with greater preoperative left hippocampal and left frontal activation for verbal fluency (VF). In left TLE, stronger preoperative left middle frontal activation for VF was predictive of greater decline in naming after ATLR. Postoperatively, in left TLE with clinically significant naming decline, greater right middle frontal VF activation correlated with better postoperative naming. In patients without postoperative naming decline, better naming correlated with greater activation in the remaining left posterior hippocampus. In right TLE, naming ability correlated with left hippocampal and left and right frontal VF activation postoperatively.
  
  
  CONCLUSIONS
  In left TLE, early postoperative reorganization to the contralateral frontal lobe suggests multiple systems support language function. Postoperatively, ipsilateral recruitment involving the posterior hippocampal remnant is important for maintaining language, and reorganization to the contralateral hemisphere is less effective. Preoperative left middle frontal activation for VF was predictive of naming decline in left TLE after ATLR.
authors.affiliation: Epilepsy Society MRI Unit, Epilepsy Society, Chalfont St Peter, Buckinghamshire, UK.
authors.forename: Silvia B
authors.initials: SB
authors.lastname: Bonelli
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Thompson
authors.forename: Mahinda
authors.initials: M
authors.lastname: Yogarajah
authors.forename: Christian
authors.initials: C
authors.lastname: Vollmar
authors.forename: Robert H W
authors.initials: RH
authors.lastname: Powell
authors.forename: Mark R
authors.initials: MR
authors.lastname: Symms
authors.forename: Andrew W
authors.initials: AW
authors.lastname: McEvoy
authors.forename: Caroline
authors.initials: C
authors.lastname: Micallef
authors.forename: Matthias J
authors.initials: MJ
authors.lastname: Koepp
authors.forename: John S
authors.initials: JS
authors.lastname: Duncan
mesh_terms: D000293:Adolescent; D000328:Adult; D038481:Anterior Temporal Lobectomy / Q000009:adverse effects* / Q000379:methods; D001931:Brain Mapping; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000473:pathology / Q000601:surgery; D005260:Female; D005625:Frontal Lobe / Q000098:blood supply* / Q000473:pathology; D005820:Genetic Testing; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007806:Language Disorders / Q000209:etiology*; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000098:blood supply; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014705:Verbal Behavior; D055815:Young Adult
chemical_list: D010100:Oxygen