Increased striatal serotonin synthesis following cortical resection in children with intractable epilepsy

Background and purpose: Serotonin is a major regulator of structural brain plasticity, which may occur following cortical resection in humans. In this study we used positron emission tomography (PET) with alpha[C-11]methyl-L-tryptophan (AMT) to evaluate serotonergic alterations in subcortical structures following cortical resection in children with intractable epilepsy. Methods: AMT uptake in the thalamus and lentiform nucleus was evaluated postoperatively (1-89 months following resection) in 19 children (mean age: 8.7 years) with a previous cortical resection due to intractable epilepsy. Ten children with partial epilepsy but without resection and seven normal children served as controls. Results: There was an increased AMT uptake in the lentiform nucleus ipsilateral to the resection as compared to the contralateral side (mean asymmetry: 4.2 +/- 3.0%), and the asymmetries were significantly higher than those measured in the control groups (p < 0.001). Post-resection asymmetry indices in the lentiform nucleus correlated inversely with postoperative time (r = -0.67; p = 0.002), but not with age (p = 0.29) or the extent of resection (p = 0.77). In contrast, thalamic AMT uptake asymmetries were not different among the three groups (p = 0.63). Conclusions: Cortical resection results in a sustained increase of AMT uptake in the lentiform nucleus, suggesting increased serotonin synthesis. Serotonergic activation in the deafferented striatum may play a role in the functional reorganization of cortico-striatal projections in humans. (C) 2007 Elsevier B.V. All rights reserved.