Functional MRI (fMRI) and Diffusion Tensor Imaging (DTI) in Temporal Lobe Epilepsy

OBJECTIVES: Epilepsy surgery is emerging as a potent therapeutic intervention for a large group of patients with uncontrolled temporal lobe epilepsy, particularly when performed early in the course of the illness. Seizure freedom is an important goal of seizure surgery, but post-operative neuropsychological functioning is another equally important outcome measure. Both endpoints require careful pre-operative evaluation of the individual patient and better understanding of the functional neuroanatomy of the temporal lobe. In this study fMRI and DTI will be performed in patients with temporal lobe epilepsy and normal volunteers in an attempt to 1. investigate the role of the anterior temporal cortex in semantic processing, 2. evaluate the role of the amygdala in affective processing, 3. correlate the extent of white matter pathway resection with cognitive outcome after temporal lobectomy. STUDY POPULATION: We plan to study 30 patients with temporal lobe epilepsy (right-sided, left-sided seizure foci) pre and post temporal lobectomy as well as 30 normal volunteers. DESIGN: The study will be done in two parts both consisting of identical tasks. For the patient group part 1 will be performed prior to temporal lobectomy and part 2, 6-12 months after temporal lobectomy. For the normal volunteer group parts 1 and 2 will be performed at time interval of 6-12 months. During part 1 all study subjects will undergo neuropsychological evaluation. FMRI will be performed with two tasks: animal and tool naming (to evaluate semantic processing) and rating of emotionally pleasant or unpleasant pictures (to evaluate affective processing). All subjects will also undergo diffusion tensor imaging (DTI) for the visualization of white matter pathways. During part 2 of the study all of the above tests will be repeated. FMRI data will be analyzed within the framework of the general linear model in a program such as AFNI 2.5. Statistical comparisons between activation patterns in scans acquired during part 1 and part 2 within either group (intragroup comparison) will be done by voxel wise paired t-test. In a second analysis all 4 groups will be compared in a mixed model. The DTI data will be correlated with the neuropsychological outcome to asses the contribution of white matter abnormalities pre-operatively or severance of white matter pathways post-operative on neuropsychological functioning. OUTCOME PARAMETERS: Outcome parameters are changes in the fMRI activation pattern post temporal lobectomy and disruption of anisotropy on the diffusion tensor images.