Abstracts

Rationale: Recent studies have shown reorganization of language networks in patients with temporal lobe epilepsy. However, these studies were cross-sectional. We addressed the reorganization of language network longitudinally using diffusion tensor imaging (DTI), an MRI method that allows the assessment of white matter microstructure and integrity in vivo. In the present study, we evaluate the right arcuate fasciculus (rARF) following resection of the left ARF (lARF) in children with intractable epilepsy. Methods: We selected 10 children with intractable epilepsy whose resections included the lARF and who had DTI-MRI scans at both pre-surgery and post-surgery timepoints (age at pre-surgery scan: 4.75 /- 3.72 years; age at post-surgery scan: 5.60 /- 3.63 years; duration between surgery and post-surgery scan: 0.62 /- 0.35 years; 5 males). Tensor calculation and tractography were performed using DTI Studio (Jiang H et al., Comput Methods program Biomed 2006;81:106-16) with starting and ending FA threshold values of 0.2. Right ARF on both pre-surgery and post-surgery scans were isolated using a protocol described previously (Sundaram SK et al., J Pediatr 2008;152:250-5). The morphological appearance and the mean FA values of the isolated rARF fiber tracts were evaluated. Results: A repeated measures analysis of the rARF showed a significant (p = 0.051) increase in the mean FA values for the post-surgery scans (0.446 /- 0.008) compared to the pre-surgical scans (0.416 /- 0.011) after controlling for age. Furthermore, the change in FA values of the rARF from pre-surgery scan to post-surgery scan showed a near significant positive correlation with duration between lARF resection and post-surgical scan (Pearson s r = 0.59; p = 0.07). In addition, 8 out of the 10 children showed marked enlargement of the right ARF postsurgically (see Figure 1). Conclusions: Our results show an increase in the FA values and morphological enlargement of the rARF following resection of lARF in children with intractable epilepsy. These findings suggest a compensatory reorganization in the rARF beyond the age-related maturational changes, presumably triggered by resection of the lARF.