Functional MR imaging in assessment of language dominance in epileptic patients

Neuroimage. 2003 Feb;18(2):460-7. doi: 10.1016/s1053-8119(03)00025-9.

Abstract

The value of functional MR Imaging (fMRI) in assessing language lateralization in epileptic patients candidate for surgical treatment is increasingly recognized. However few data are available for left-handed patients. Moreover determining factors for atypical dominance in patients investigated with contemporary imaging have not been reported. We studied 20 patients (14 males, 6 females; 9 right handed, 11 left handed) aged from 9 to 48 years, investigated for intractable partial epilepsy. Epileptic focus location was temporal in 14 cases, extratemporal in 6, and lateralized in the left hemisphere in 11/20. Hemispheric dominance for language was evaluated by both Wada test and fMRI using a silent word generation paradigm in all patients. Furthermore, a postictal speech test was performed in 15 patients. An fMRI language lateralization index was calculated from the number of activated pixels (Student's t test, P < 0.0001) in the right and left hemispheres. The Wada test showed a right hemispheric dominance in 8 patients (6 were left handed and 2 right handed) and a left hemispheric dominance in 12 patients (5 were left handed and 7 right handed). These results were concordant with clinical postictal examination in 11/15 patients (73%). Clinical status did not allow a conclusion about hemispheric dominance for the remaining 4 patients. FMRI was concordant with the Wada test in 19/20 cases. For one left-handed patient, fMRI showed bilateral activation, whereas the Wada test demonstrated a right hemispheric dominance. Right language lateralization was significantly correlated with left lateralized epilepsy (P < 0.05) but was not correlated with age at epilepsy onset, early brain injury (before 6 years), and lobar localization of epileptogenic focus. However the lack of a significant relationship between these factors and atypical language lateralization may be related to the small sample size.

MeSH terms

  • Adolescent
  • Adult
  • Amobarbital
  • Anomia / physiopathology
  • Brain Mapping
  • Child
  • Dominance, Cerebral / physiology*
  • Electroencephalography*
  • Epilepsy, Temporal Lobe / physiopathology*
  • Female
  • Humans
  • Image Processing, Computer-Assisted*
  • Language Tests
  • Magnetic Resonance Imaging*
  • Male
  • Middle Aged
  • Reading*
  • Sensitivity and Specificity
  • Speech Perception / physiology*
  • Verbal Behavior / physiology*

Substances

  • Amobarbital