OBJECTIVE: Functional MRI (FMRI) was used to investigate the effect of
medial temporal lobe (MTL) pathology on activation of language
encoding areas in patients with temporal lobe epilepsy (TLE). METHODS:
Whole- brain FMRI was obtained. Twenty-eight patients with either left
TLE (LTLE) or right TLE (RTLE) performed a semantic decision task
alternating with an auditory perceptual task. RESULTS: Activation of
language areas in the frontal and parietal lobes was similar in both
groups, with no group differences in the total number of active
voxels. However, the RTLE group showed much stronger activation of the
left MTL, including the hippocampus, parahippocampal gyrus, and
collateral sulcus, than did the LTLE group. CONCLUSIONS: Activation of
the left MTL during semantic encoding discriminates patients with RTLE
and LTLE. This FMRI technique may potentially be of use in determining
memory lateralization and for predicting the side of seizure focus in
TLE.