title: Is language lateralization in temporal lobe epilepsy patients related to the nature of the epileptogenic lesion?
abstract: OBJECTIVE
  Early acquired lesions are considered to be a risk factor for atypical language lateralization in epilepsy, whereas developmental lesions are not. Hippocampal sclerosis (HS) can be understood as an early, acquired lesion, whereas developmental tumors (DT) are thought to originate in utero. We assessed whether language lateralization differs between these groups of temporal lobe epilepsy patients.
  
  
  METHODS
  We used 3-Tesla functional MRI (fMRI) to assess 41 patients (16 DT, 25 HS) and 50 controls, performing a noun-verb-generation task. fMRI data were processed by using SPM2. A laterality index (LI) was calculated based on the number of activated voxels in left- and right-sided frontal lobe language areas. Atypical lateralization was considered if the index was < or = 0.2.
  
  
  RESULTS
  Patients had a lower LI (0.42 +/- 0.5) than controls (0.6 +/- 0.3; p < or = 0.05), but the LI was not different between DT (0.44 +/- 0.5) and HS patients (0.43 +/- 0.4; p = 0.9). The frequency of atypical lateralization was increased in patients (27%) compared with controls (8%) but was similar in both patient groups (DT, 31%; HS, 24%). HS patients had an earlier onset and longer duration of epilepsy and a higher frequency of significant antecedent events (p < or = 0.05).
  
  
  CONCLUSIONS
  Patients with TLE demonstrate a deviation toward atypical language lateralization. However, language lateralization was not different between patients with presumably acquired lesions compared with patients with developmental pathology. This suggests that the nature of the temporal lobe lesion does not influence overall language lateralization.
authors: Brain Research Institute, Heidelberg West, Victoria, Australia.
authors: Regula S
authors: RS
authors: Briellmann
authors: Angelo
authors: A
authors: Labate
authors: A Simon
authors: AS
authors: Harvey
authors: Michael M
authors: MM
authors: Saling
authors: Christina
authors: C
authors: Sveller
authors: Leasha
authors: L
authors: Lillywhite
authors: David F
authors: DF
authors: Abbott
authors: Graeme D
authors: GD
authors: Jackson